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Sample records for aileron pushrod bearings

  1. Pushrod assembly

    DOEpatents

    Potter, Jerry D.

    1987-01-01

    A pushrod assembly including a carriage mounted on a shaft for movement therealong and carrying a pushrod engageable with a load to be moved. A magnet is mounted on a supporting bracket for movement along such shaft. Means are provided for adjustably spacing said magnet away from said carriage to obtain a selected magnetic attractive or coupling force therebetween. Movement of the supporting bracket and the magnet carried thereby pulls the carriage along with it until the selected magnetic force is exceeded by a resistance load acting on the carriage.

  2. Gasket with pushrod retainer

    DOEpatents

    Knudsen, Julian R.; Welch, Christopher B.

    2005-04-26

    In an engine having a rocker member adapted to rock about an axis intermediate the rocker member and a pushrod extending from a lower body to an upper body and engaging an end of the rocker member, a gasket for sealing the lower body to the upper body is provided. The gasket includes a sealing portion adapted to substantially seal at least a portion of the upper body to the lower body, and a pushrod support portion extending outwardly from the sealing portion adapted to engage the pushrod. At least a portion of the pushrod support portion engaging the pushrod is constructed from a material that is softer than the material of the pushrod.

  3. Wind turbine rotor aileron

    DOEpatents

    Coleman, Clint; Kurth, William T.

    1994-06-14

    A wind turbine has a rotor with at least one blade which has an aileron which is adjusted by an actuator. A hinge has two portions, one for mounting a stationary hinge arm to the blade, the other for coupling to the aileron actuator. Several types of hinges can be used, along with different actuators. The aileron is designed so that it has a constant chord with a number of identical sub-assemblies. The leading edge of the aileron has at least one curved portion so that the aileron does not vent over a certain range of angles, but vents if the position is outside the range. A cyclic actuator can be mounted to the aileron to adjust the position periodically. Generally, the aileron will be adjusted over a range related to the rotational position of the blade. A method for operating the cyclic assembly is also described.

  4. Numerical design of an adaptive aileron

    NASA Astrophysics Data System (ADS)

    Amendola, Gianluca; Dimino, Ignazio; Concilio, Antonio; Magnifico, Marco; Pecora, Rosario

    2016-04-01

    The study herein described is aimed at investigating the feasibility of an innovative full-scale camber morphing aileron device. In the framework of the "Adaptive Aileron" project, an international cooperation between Italy and Canada, this goal was carried out with the integration of different morphing concepts in a wing-tip prototype. As widely demonstrated in recent European projects such as Clean Sky JTI and SARISTU, wing trailing edge morphing may lead to significant drag reduction (up to 6%) in off-design flight points by adapting chord-wise camber variations in cruise to compensate A/C weight reduction following fuel consumption. Those researches focused on the flap region as the most immediate solution to implement structural adaptations. However, there is also a growing interest in extending morphing functionalities to the aileron region preserving its main functionality in controlling aircraft directional stability. In fact, the external region of the wing seems to be the most effective in producing "lift over drag" improvements by morphing. Thus, the objective of the presented research is to achieve a certain drag reduction in off-design flight points by adapting wing shape and lift distribution following static deflections. In perspective, the developed device could also be used as a load alleviation system to reduce gust effects, augmenting its frequency bandwidth. In this paper, the preliminary design of the adaptive aileron is first presented, assessed on the base of the external aerodynamic loads. The primary structure is made of 5 segmented ribs, distributed along 4 bays, each splitted into three consecutive parts, connected with spanwise stringers. The aileron shape modification is then implemented by means of an actuation system, based on a classical quick-return mechanism, opportunely suited for the presented application. Finite element analyses were assessed for properly sizing the load-bearing structure and actuation systems and for

  5. Advanced composite aileron for L-1011 transport aircraft: Aileron manufacture

    NASA Technical Reports Server (NTRS)

    Dunning, E. G.; Cobbs, W. L.; Legg, R. L.

    1981-01-01

    The fabrication activities of the Advanced Composite Aileron (ACA) program are discussed. These activities included detail fabrication, manufacturing development, assembly, repair and quality assurance. Five ship sets of ailerons were manufactured. The detail fabrication effort of ribs, spar and covers was accomplished on male tools to a common cure cycle. Graphite epoxy tape and fabric and syntactic epoxy materials were utilized in the fabrication. The ribs and spar were net cured and required no post cure trim. Material inconsistencies resulted in manufacturing development of the front spar during the production effort. The assembly effort was accomplished in subassembly and assembly fixtures. The manual drilling system utilized a dagger type drill in a hydraulic feed control hand drill. Coupon testing for each detail was done.

  6. Aileron controls for wind turbine applications

    NASA Technical Reports Server (NTRS)

    Miller, D. R.; Putoff, R. L.

    1984-01-01

    Horizontal axis wind turbines which utilize partial or full variable blade pitch to regulate rotor speed were examined. The weight and costs of these systems indicated a need for alternate methods of rotor control. Aileron control is an alternative which has potential to meet this need. Aileron control rotors were tested on the Mod-O wind turbine to determine their power regulation and shutdown characteristics. Test results for a 20 and 38% chord aileron control rotor are presented. Test is shown that aileron control is a viable method for safety for safely controlling rotor speed, following a loss of general load.

  7. Calculation of transonic aileron buzz

    NASA Technical Reports Server (NTRS)

    Steger, J. L.; Bailey, H. E.

    1979-01-01

    An implicit finite-difference computer code that uses a two-layer algebraic eddy viscosity model and exact geometric specification of the airfoil has been used to simulate transonic aileron buzz. The calculated results, which were performed on both the Illiac IV parallel computer processor and the Control Data 7600 computer, are in essential agreement with the original expository wind-tunnel data taken in the Ames 16-Foot Wind Tunnel just after World War II. These results and a description of the pertinent numerical techniques are included.

  8. 14 CFR 23.455 - Ailerons.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ailerons. 23.455 Section 23.455 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Ailerons and...

  9. Flutter prediction for a wing with active aileron control

    NASA Technical Reports Server (NTRS)

    Penning, K.; Sandlin, D. R.

    1983-01-01

    A method for predicting the vibrational stability of an aircraft with an analog active aileron flutter suppression system (FSS) is expained. Active aileron refers to the use of an active control system connected to the aileron to damp vibrations. Wing vibrations are sensed by accelerometers and the information is used to deflect the aileron. Aerodynamic force caused by the aileron deflection oppose wing vibrations and effectively add additional damping to the system.

  10. Nonclassical aileron buzz in transonic flow

    NASA Technical Reports Server (NTRS)

    Bendiksen, Oddvar O.

    1993-01-01

    A computational study of inviscid, transonic aileron and trailing-edge buzz instabilities is presented. A mixed Eulerian-Lagrangian formulation is used to model the fluid-structure system and to obtain a system of space-discretized equations that is time-marched to simulate the aeroelastic behavior of the wing-aileron system. Results obtained suggest that shock-induced separation may not be an essential driving force behind all buzz phenomena. Several examples are shown where the shock motion interacts with the aileron motion to extract energy from the flow. If the trailing-edge region is sufficiently flexible and the shocks are at the trailing edge, a trailing-edge buzz instability appears possible.

  11. Advanced wind turbine with lift-destroying aileron for shutdown

    DOEpatents

    Coleman, Clint; Juengst, Theresa M.; Zuteck, Michael D.

    1996-06-18

    An advanced aileron configuration for wind turbine rotors featuring an aileron with a bottom surface that slopes upwardly at an angle toward the nose region of the aileron. The aileron rotates about a center of rotation which is located within the envelope of the aileron, but does not protrude substantially into the air flowing past the aileron while the aileron is deflected to angles within a control range of angles. This allows for strong positive control of the rotation of the rotor. When the aileron is rotated to angles within a shutdown range of deflection angles, lift-destroying, turbulence-producing cross-flow of air through a flow gap, and turbulence created by the aileron, create sufficient drag to stop rotation of the rotor assembly. The profile of the aileron further allows the center of rotation to be located within the envelope of the aileron, at or near the centers of pressure and mass of the aileron. The location of the center of rotation optimizes aerodynamically and gyroscopically induced hinge moments and provides a fail safe configuration.

  12. Viability of Pushrod Dilatometry Techniques for High Temperature In-Pile Measurements

    SciTech Connect

    J. E. Daw; J. L. Rempe; D. L. Knudson; K. G. Condie; J. C. Crepeau

    2008-03-01

    To evaluate the performance of new fuel, cladding, and structural materials for use in advanced and existing nuclear reactors, robust instrumentation is needed. Changes in material deformation are typically evaluated out-of-pile, where properties of materials are measured after samples were irradiated for a specified length of time. To address this problem, a series of tests were performed to examine the viability of using pushrod dilatometer techniques for in-pile instrumentation to measure deformation. The tests were performed in three phases. First, familiarity was gained in the use and accuracy of this system by testing samples with well defined thermal elongation characteristics. Second, high temperature data for steels, specifically SA533 Grade B, Class 1 (SA533B1) Low Alloy Steel and Stainless Steel 304 (SS304), found in Light Water Reactor (LWR) vessels, were aquired. Finally, data were obtained from a short pushrod in a horizontal geometry to data obtained from a longer pushrod in a vertical geometry, the configuration likely to be used for in-situ measurements. Results of testing show that previously accepted data for the structural steels tested, SA533B1 and SS304, are inaccurate at high temperatures (above 500 oC) due to extrpolation of high temperature data. This is especially true for SA533B1, as previous data do not account for the phase transformation of the material between 730 oC and 830 oC. Also, comparison of results for horizontal and vertical configurations show a maximum percent difference of 2.02% for high temperature data.

  13. Experimental characterization of an adaptive aileron: lab tests and FE correlation

    NASA Astrophysics Data System (ADS)

    Amendola, Gianluca; Dimino, Ignazio; Amoroso, Francesco; Pecora, Rosario

    2016-04-01

    Like any other technology, morphing has to demonstrate system level performance benefits prior to implementation onto a real aircraft. The current status of morphing structures research efforts (as the ones, sponsored by the European Union) involves the design of several subsystems which have to be individually tested in order to consolidate their general performance in view of the final integration into a flyable device. This requires a fundamental understanding of the interaction between aerodynamic, structure and control systems. Important worldwide research collaborations were born in order to exchange acquired experience and better investigate innovative technologies devoted to morphing structures. The "Adaptive Aileron" project represents a joint cooperation between Canadian and Italian research centers and leading industries. In this framework, an overview of the design, manufacturing and testing of a variable camber aileron for a regional aircraft is presented. The key enabling technology for the presented morphing aileron is the actuation structural system, integrating a suitable motor and a load-bearing architecture. The paper describes the lab test campaign of the developed device. The implementation of a distributed actuation system fulfills the actual tendency of the aeronautical research to move toward the use of electrical power to supply non-propulsive systems. The aileron design features are validated by targeted experimental tests, demonstrating both its adaptive capability and robustness under operative loads and its dynamic behavior for further aeroelastic analyses. The experimental results show a satisfactory correlation with the numerical expectations thus validating the followed design approach.

  14. Advanced wind turbine with lift canceling aileron for shutdown

    SciTech Connect

    Coleman, C.; Juengst, T.M.; Zuteck, M.D.

    1996-06-18

    An advanced aileron configuration is described for wind turbine rotors featuring an independent, lift generating aileron connected to the rotor blade. The aileron has an airfoil profile which is inverted relative to the airfoil profile of the main section of the rotor blade. The inverted airfoil profile of the aileron allows the aileron to be used for strong positive control of the rotation of the rotor while deflected to angles within a control range of angles. The aileron functions as a separate, lift generating body when deflected to angles within a shutdown range of angles, generating lift with a component acting in the direction opposite the direction of rotation of the rotor. Thus, the aileron can be used to shut down rotation of the rotor. The profile of the aileron further allows the center of rotation to be located within the envelope of the aileron, at or near the centers of pressure and mass of the aileron. The location of the center of rotation optimizes aerodynamically and gyroscopically induced hinge moments and provides a fail safe configuration. 24 figs.

  15. Advanced wind turbine with lift cancelling aileron for shutdown

    DOEpatents

    Coleman, Clint; Juengst, Theresa M.; Zuteck, Michael D.

    1996-06-18

    An advanced aileron configuration for wind turbine rotors featuring an independent, lift generating aileron connected to the rotor blade. The aileron has an airfoil profile which is inverted relative to the airfoil profile of the main section of the rotor blade. The inverted airfoil profile of the aileron allows the aileron to be used for strong positive control of the rotation of the rotor while deflected to angles within a control range of angles. The aileron functions as a separate, lift generating body when deflected to angles within a shutdown range of angles, generating lift with a component acting in the direction opposite the direction of rotation of the rotor. Thus, the aileron can be used to shut down rotation of the rotor. The profile of the aileron further allows the center of rotation to be located within the envelope of the aileron, at or near the centers of pressure and mass of the aileron. The location of the center of rotation optimizes aerodynamically and gyroscopically induced hinge moments and provides a fail safe configuration.

  16. Aeroelastic stability of wind turbine blade/aileron systems

    NASA Technical Reports Server (NTRS)

    Strain, J. C.; Mirandy, L.

    1995-01-01

    Aeroelastic stability analyses have been performed for the MOD-5A blade/aileron system. Various configurations having different aileron torsional stiffness, mass unbalance, and control system damping have been investigated. The analysis was conducted using a code recently developed by the General Electric Company - AILSTAB. The code extracts eigenvalues for a three degree of freedom system, consisting of: (1) a blade flapwise mode; (2) a blade torsional mode; and (3) an aileron torsional mode. Mode shapes are supplied as input and the aileron can be specified over an arbitrary length of the blade span. Quasi-steady aerodynamic strip theory is used to compute aerodynamic derivatives of the wing-aileron combination as a function of spanwise position. Equations of motion are summarized herein. The program provides rotating blade stability boundaries for torsional divergence, classical flutter (bending/torsion) and wing/aileron flutter. It has been checked out against fixed-wing results published by Theodorsen and Garrick. The MOD-5A system is stable with respect to divergence and classical flutter for all practical rotor speeds. Aileron torsional stiffness must exceed a minimum critical value to prevent aileron flutter. The nominal control system stiffness greatly exceeds this minimum during normal operation. The basic system, however, is unstable for the case of a free (or floating) aileron. The instability can be removed either by the addition of torsional damping or mass-balancing the ailerons. The MOD-5A design was performed by the General Electric Company, Advanced Energy Program Department under Contract DEN3-153 with NASA Lewis Research Center and sponsored by the Department of Energy.

  17. Advanced composite aileron for L-1011 transport aircraft: Ground tests and flight evaluation

    NASA Technical Reports Server (NTRS)

    Griffin, C. F.

    1981-01-01

    A composite aileron and a metal aileron were subjected to a series of comparative stiffness and vibration tests. These tests showed that the stiffness and vibration characteristics of the composite aileron are similar to the metal aileron. The first composite ground test article was statically tested to failure which occurred at 139 percent of design ultimate load. The second composite ground test article was tested to verify damage tolerance and fail-safe characteristics. Visible damage was inflicted to the aileron and the aileron was subjected to one lifetime of spectrum fatigue loading. After conducting limit load tests on the aileron, major damage was inflicted to the cover and the aileron was loaded to failure which occurred at 130 percent of design ultimate load. A shipset of composite ailerons were installed on Lockheed's L-1011 flight test aircraft and flown. The composite aileron was flutter-free throughout the flight envelope.

  18. Advanced composite aileron for L-1011 transport aircraft

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Design and evaluation of alternate concepts for the major subcomponents of the advanced composite aileron (ACA) was completed. From this array of subcomponents, aileron assemblies were formulated and evaluated. Based on these analyses a multirib assembly with graphite tape/syntactic core covers, a graphite tape front spar, and a graphite fabric rib was selected for development. A weight savings of 29.1 percent (40.8 pounds per aileron) is predicted. Engineering cost analyses indicate that the production cost of the ACA will be 7.3 percent less than the current aluminum aileron. Fabrication, machining, and testing of the material evaluation specimens for the resin screening program was completed. The test results lead to the selection of Narmco 5208 resin for the ACA. Other activities completed include: the detailed design of the ACA, construction of a three dimensional finite element model for structural analysis, and formulation of detail plans for material verification and process development.

  19. Aileron roll hysteresis effects on entry of space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Powell, R. W.

    1977-01-01

    Six-degree-of-freedom simulations of the space shuttle orbiter entry with control hysteresis were conducted on the NASA Langley Research Center interactive simulator known as the automatic reentry flight dynamics simulator. These simulations revealed that the vehicle can tolerate control hysteresis producing a + or - 50 percent change in the nominal aileron roll characteristics and an offset in the nominal characteristics equivalent to a + or - 5 deg aileron deflection with little increase in the reaction control system's fuel consumption.

  20. Summary of NASA/DOE Aileron-Control Development Program for Wind Turbines

    NASA Technical Reports Server (NTRS)

    Miller, D. R.

    1986-01-01

    The development of aileron-control for wind turbines is discussed. Selected wind tunnel test results and full-scale rotor test results are presented for various types of ailerons. Finally, the current status of aileron-control development is discussed. Aileron-control was considered as a method of rotor control for use on wind turbines based on its potential to reduce rotor weight and cost. Following an initial feasibility study, a 20 percent chord aileron-control rotor was fabricated and tested on the NASA/DOE Mod-0 experimental wind turbine. Results from these tests indicated that the 20 percent chord ailerons regulated power and provided overspeed protection, but only over a very limited windspeed range. The next aileron-control rotor to be tested on the Mod-0 had 38 percent chord ailerons and test results showed these ailerons provided overspeed protection and power regulation over the Mod-0's entire operational windspeed range.

  1. A Flight Comparison of Conventional Ailerons on a Rectangular Wing and of Conventional and Floating Wing-Tip Ailerons on a Tapered Wing

    NASA Technical Reports Server (NTRS)

    Soule, H A; Gracey, W

    1938-01-01

    Report presents the results of flight tests comparing the relative effectiveness of conventional ailerons of the same size on wings of rectangular and tapered plan forms made with a Fairchild 22 airplane. Information is included comparing conventional and floating wing-tip ailerons on a tapered wing. The results showed that the conventional ailerons were somewhat more effective on the tapered than on the rectangular wing. The difference, however, was so small as to be imperceptible to the pilots. The floating wing-tip ailerons were only half as effective as the conventional ailerons and, for this reason, were considered unsatisfactory.

  2. On the distribution of lift along the span of an airfoil with displaced ailerons

    NASA Technical Reports Server (NTRS)

    Munk, Max M

    1924-01-01

    The effect of an aileron displacement on the distribution of the lift along the span is computed for an elliptic wing of aspect ratio 6 for three conditions. The lift distribution caused by the aileron displacement is uniform and extends normally beyond the inner end of the ailerons. Hence, the displacement of an aileron with constant chord length may bring about passing the stalling point of the adjacent wing sections, if these were near this point before. Hence, such ailerons can become ineffective at low speeds. Tapering the aileron towards the inside suggests itself as a remedy.

  3. The Distribution of Lift Over Wing Tips and Ailerons

    NASA Technical Reports Server (NTRS)

    Bacon, David L

    1924-01-01

    This investigation was carried out in the 5-foot wind tunnel of the Langley Memorial Aeronautical Laboratory for the purpose of obtaining more complete information on the distribution of lift between the ends of wing spars, the stresses in ailerons, and the general subject of airflow near the tip of a wing. It includes one series of tests on four models without ailerons, having square, elliptical, and raked tips respectively, and a second series of positively and negatively raked wings with ailerons adjusted to different settings. The results show that negatively raked tips give a more uniform distribution of air pressure than any of the other three arrangements, because the tip vortex does not disturb the flow at the trailing edge. Aileron loads are found to be less severe on wings with negative application to the calculation of aileron and wing stresses and also to facilitate the proper distribution of load in sand testing. Contour charts show in great detail the complex distribution lift over the wing.

  4. Effect of Compressibility on Pressure Distribution over an Airfoil with a Slotted Frise Aileron

    NASA Technical Reports Server (NTRS)

    Luoma, Avro A

    1944-01-01

    Pressure distribution measurements were made over an airfoil with slotted Frise aileron up to 0.76 Mach at various angles of attack and aileron defections. Section characteristics were determined from these pressure data. Results indicated loss of aileron rolling power for deflections ranging from -12 Degrees to -19 Degrees. High stick forces for non-differential deflections incurred at high speed, which were due to overbalancing tendency of up-moving aileron, may precipitate serious control difficulties. Detailed results are presented graphically.

  5. Shutdown characteristics of the Mod-O wind turbine with aileron controls

    NASA Technical Reports Server (NTRS)

    Miller, D. R.; Corrigan, R. D.

    1984-01-01

    Horizontal-axis wind turbines utilize partial or full variable blade pitch to regulate rotor speed. The weight and costs of these systems indicated a need for alternate methods of rotor control. Aileron control is an alternative which has potential to meet this need. The NASA Lewis Research Center has been experimentally testing aileron control rotors on the Mod-U wind turbine to determine their power regulation and shutdown characteristics. Experimental and analytical shutdown test results are presented for a 38 percent chord aileron-control rotor. These results indicated that the 38 percent chord ailerons provided overspeed protection over the entire Mod-O operational windspeed range, and had a no-load equilibrium tip speed ratio of 1.9. Thus, the 38 percent chord ailerons had much improved aerodynamic braking capability when compared with the first aileron-control rotor having 20 percent chord ailerons.

  6. Producibility aspects of advanced composites for an L-1011 Aileron

    NASA Technical Reports Server (NTRS)

    Van Hamersveld, J.; Fogg, L. D.

    1976-01-01

    The design of advanced composite aileron suitable for long-term service on transport aircraft includes Kevlar 49 fabric skins on honeycomb sandwich covers, hybrid graphite/Kevlar 49 ribs and spars, and graphite/epoxy fittings. Weight and cost savings of 28 and 20 percent, respectively, are predicted by comparison with the production metallic aileron. The structural integrity of the design has been substantiated by analysis and static tests of subcomponents. The producibility considerations played a key role in the selection of design concepts with potential for low-cost production. Simplicity in fabrication is a major factor in achieving low cost using advanced tooling and manufacturing methods such as net molding to size, draping, forming broadgoods, and cocuring components. A broadgoods dispensing machine capable of handling unidirectional and bidirectional prepreg materials in widths ranging from 12 to 42 inches is used for rapid layup of component kits and covers. Existing large autoclaves, platen presses, and shop facilities are fully exploited.

  7. Considerations affecting the additional weight required in mass balance of ailerons

    NASA Technical Reports Server (NTRS)

    Diehl, W S

    1937-01-01

    This paper is essentially a consideration of mass balance of ailerons from a preliminary design standpoint, in which the extra weight of the mass counterbalance is the most important phase of the problem. Equations are developed for the required balance weight for a simple aileron and this weight is correlated with the mass-balance coefficient. It is concluded the location of the c.g. of the basic aileron is of paramount importance and that complete mass balance imposes no great weight penalty if the aileron is designed to have its c.g. inherently near to the hinge axis.

  8. Wind-Tunnel Development of Ailerons for the Curtiss XP-60 Airplanem Special Report

    NASA Technical Reports Server (NTRS)

    Rogallo, F. M.; Lowry, John G.

    1942-01-01

    An investigation was made in the LWAL 7- by 10-foot tunnel of internally balanced, sealed ailerons for the Curtiss XP-60 airplane. Ailerons with tabs and. with various amounts of balance were tested. Stick forces were estimated for several aileron arrangements including an arrangement recommended for the airplane. Flight tests of the recommended arrangement are discussed briefly in an appendix, The results of the wind-tunnel and flight tests indicate that the ailerons of large or fast airplanes may be satisfactorily balanced by the method developed.

  9. Advanced composite aileron for L-1011 transport aircraft: Design and analysis

    NASA Technical Reports Server (NTRS)

    Griffin, C. F.; Fogg, L. D.; Dunning, E. G.

    1981-01-01

    Detail design of the composite aileron has been completed. The aileron design is a multi-rib configuration with single piece upper and lower covers mechanically fastened to the substructure. Covers, front, spar and ribs are fabricated with graphite/epoxy tape or fabric composite material. The design has a weight savings of 23 percent compared to the aluminum aileron. The composite aileron has 50 percent fewer fasteners and parts than the metal aileron and is predicted to be cost competitive. Structural integrity of the composite aileron was verified by structural analysis and an extensive test program. Static, failsafe, and vibration analyses have been conducted on the composite aileron using finite element models and specialized computer programs for composite material laminates. The fundamental behavior of the composite materials used in the aileron was determined by coupon tests for a variety of environmental conditions. Critical details of the design were interrogated by static and fatigue tests on full-scale subcomponents and subassemblies of the aileron.

  10. Aircraft wing structural detail design (wing, aileron, flaps, and subsystems)

    NASA Technical Reports Server (NTRS)

    Downs, Robert; Zable, Mike; Hughes, James; Heiser, Terry; Adrian, Kenneth

    1993-01-01

    The goal of this project was to design, in detail, the wing, flaps, and ailerons for a primary flight trainer. Integrated in this design are provisions for the fuel system, the electrical system, and the fuselage/cabin carry-through interface structure. This conceptual design displays the general arrangement of all major components in the wing structure, taking into consideration the requirements set forth by the appropriate sections of Federal Aviation Regulation Part 23 (FAR23) as well as those established in the statement of work.

  11. Advanced composite aileron for L-1011 transport aircraft, task 1

    NASA Technical Reports Server (NTRS)

    Griffin, C. F.; Fogg, L. D.; Stone, R. L.; Dunning, E. G.

    1978-01-01

    Structural design and maintainability criteria were established and used as a guideline for evaluating a variety of configurations and materials for each of the major subcomponents. From this array of subcomponent designs, several aileron assemblies were formulated and analyzed. The selected design is a multirib configuration with sheet skin covers mechanically fastened to channel section ribs and spars. Qualitative analysis of currently available composite material systems led to the selection of three candidate materials on which comparative structural tests were conducted to measure the effects of environment and impact damage on mechanical property retention. In addition, each system was evaluated for producibility characteristics. From these tests, Thornel 300/5208 unidirectional tape was selected for the front spar and covers, and Thornel 300 fabric/5208 was chosen for the ribs.

  12. Acoustic tests of the MOD-O/5A wind turbine rotor with two different ailerons

    NASA Technical Reports Server (NTRS)

    Shepherd, K. P.; Hubbard, H. H.

    1984-01-01

    The noise of a MOD-O wind turbine generator rotor equipped with plain and balanced partial span ailerons for lift and drag control was measured. Data were obtained for a wide range of aileron deflection angles and for limited ranges of wind velocity and power output. Noise levels increased as deflection angles increased and were higher in the upwind than in the downwind direction. The plain aileron exhibited a howling noise in the frequency range 400-800 Hz at deflection angles for which flow induced cavity resonances were significant.

  13. Theoretical span loading and moments of tapered wings produced by aileron deflection

    NASA Technical Reports Server (NTRS)

    Pearson, H A

    1937-01-01

    The effect of tapered ailerons on linearly tapered wings is theoretically determined. Four different aileron spans are considered for each of three wing aspect ratios and each of four wing taper ratios. The change in lift on one half of the wing, the rolling moment, the additional induced drag, and the yawing moment, due to aileron deflection, are represented by non dimensional coefficients. Similar coefficients are given for the damping and yawing moments, the additional drag, and the change in lift, due to rolling. It was found possible to effect a fairly close agreement between the theoretical and experimental rolling moments by introducing into the theoretical expression for the rolling moment an effective change in angle of attack obtained from an analysis of flap data. The theoretical curves show that the highly tapered wing with long ailerons has a lower ratio of yawing to rolling moment and a lower additional induced drag than wings with less taper.

  14. Feasibility study of aileron and spoiler control systems for large horizontal axis wind turbines

    NASA Astrophysics Data System (ADS)

    Wentz, W. H., Jr.; Snyder, M. H.; Calhoun, J. T.

    1980-05-01

    The feasibility of using aileron or spoiler controls as alternates to pitch control for large horizontal axis wind turbines was studied. The NASA Mod-0 100 kw machine was used as the basis for the study. Specific performance studies were conducted for 20% chord ailerons over the outboard 30% span, and for 10% chord spoilers over the same portion of the span. Both control systems utilized control deflections up to 60 deg. Results of the study show that either ailerons or spoilers can provide the control necessary to limit turbine power in high wind conditions. The aileron system, as designed, provides overspeed protection at hurricane wind speeds, low wind speed starting torque of 778 N-m (574 ft. lb) at 3.6 m/sec, and a 1.3 to 1.5% increase in annual energy compared to a fixed pitch rotor. The aileron control system preliminary design study includes aileron loads analysis and the design of a failsafe flyweight actuator for overspeed protection in the event of a hydraulic system failure.

  15. Reflection plane tests of a wind turbine blade tip section with ailerons

    NASA Astrophysics Data System (ADS)

    Savino, J. M.; Nyland, T. W.; Birchenough, A. G.; Jordan, F. L.; Campbell, N. K.

    1985-08-01

    Tests were conducted in the NASA Langley 30 by 60 foot Wind Tunnel on a full scale 7.31 m (24 ft) long tip section of a wind turbine rotor blade. The blade tip section was built with ailerons on the trailing edge. The ailerons, which spanned a length of 6.1 m (20 ft), were designed so that two types could be evaluated: the plain and the balanced. The ailerons were hinged on the suction surface at the 0.62 X chord station behind the leading edge. The purpose of the tests was to measure the aerodynamic characteristics of the blade section for: an angle of attack range from 0 deg to 90 deg aileron deflections from 0 deg to -90 deg, and Reynolds numbers of 0.79 and 1.5 x 10 to the 6th power. These data were then used to determine which aileron configuration had the most desirable rotor control and aerodynamic braking characteristics. Tests were also run to determine the effects of vortex generators, leading edge roughness, and the gaps between the aileron sections on the lift, drag, and chordwise force coefficients of the blade tip section.

  16. Reflection plane tests of a wind turbine blade tip section with ailerons

    NASA Technical Reports Server (NTRS)

    Savino, J. M.; Nyland, T. W.; Birchenough, A. G.; Jordan, F. L.; Campbell, N. K.

    1985-01-01

    Tests were conducted in the NASA Langley 30 by 60 foot Wind Tunnel on a full scale 7.31 m (24 ft) long tip section of a wind turbine rotor blade. The blade tip section was built with ailerons on the trailing edge. The ailerons, which spanned a length of 6.1 m (20 ft), were designed so that two types could be evaluated: the plain and the balanced. The ailerons were hinged on the suction surface at the 0.62 X chord station behind the leading edge. The purpose of the tests was to measure the aerodynamic characteristics of the blade section for: an angle of attack range from 0 deg to 90 deg aileron deflections from 0 deg to -90 deg, and Reynolds numbers of 0.79 and 1.5 x 10 to the 6th power. These data were then used to determine which aileron configuration had the most desirable rotor control and aerodynamic braking characteristics. Tests were also run to determine the effects of vortex generators, leading edge roughness, and the gaps between the aileron sections on the lift, drag, and chordwise force coefficients of the blade tip section.

  17. Feasibility study of aileron and spoiler control systems for large horizontal axis wind turbines

    NASA Technical Reports Server (NTRS)

    Wentz, W. H., Jr.; Snyder, M. H.; Calhoun, J. T.

    1980-01-01

    The feasibility of using aileron or spoiler controls as alternates to pitch control for large horizontal axis wind turbines was studied. The NASA Mod-0 100 kw machine was used as the basis for the study. Specific performance studies were conducted for 20% chord ailerons over the outboard 30% span, and for 10% chord spoilers over the same portion of the span. Both control systems utilized control deflections up to 60 deg. Results of the study show that either ailerons or spoilers can provide the control necessary to limit turbine power in high wind conditions. The aileron system, as designed, provides overspeed protection at hurricane wind speeds, low wind speed starting torque of 778 N-m (574 ft. lb) at 3.6 m/sec, and a 1.3 to 1.5% increase in annual energy compared to a fixed pitch rotor. The aileron control system preliminary design study includes aileron loads analysis and the design of a failsafe flyweight actuator for overspeed protection in the event of a hydraulic system failure.

  18. Wind-tunnel research comparing lateral control devices, particularly at high angles of attack VI : skewed ailerons on rectangular wings

    NASA Technical Reports Server (NTRS)

    Weick, Fred E; Harris, Thomas A

    1934-01-01

    This report covers the sixth of a series of investigations in which various lateral control devices are compared with particular reference to their effectiveness at high angles of attack. The present report deals with flap-type ailerons hinged about axes having an angle with respect to the leading and trailing edges of the wing. Tests were made on four different skewed ailerons, including two different angles of skew and two sizes of ailerons. At the high angles of attack, all the skewed ailerons tested were slightly inferior with respect to rolling and yawing moments to straight ailerons having the same span and average chord. Computations indicate that the skewed ailerons are also inferior with respect to hinge moments.

  19. Wind-tunnel investigation of rectangular and tapered NACA 23012 wings with plain ailerons and full-span split flaps

    NASA Technical Reports Server (NTRS)

    Wenzinger, Carl J; Ames, Milton B , Jr

    1938-01-01

    An investigation was made to determine the aerodynamic properties of rectangular and tapered NACA 23012 wings with plain ailerons and a full-span split flap, the flap retracting ahead of the ailerons. Measurements were made of lift and drag and of pitching, rolling, yawing, and hinge moments for all conditions of full-span flaps neutral and deflected at different chord locations. The results of the tests showed that a 0.20c(sub w) full span split flap located at approximately the 0.75c(sub w) point gave higher lift coefficients than had previously been obtained with a conventional 0.20c(sub w) partial-span split flap of a length to permit satisfactory control with plain ailerons. Still higher lifts were obtained if the full-span flap, when deflected, was moved back to the aileron axis. Moving the flap back to the aileron, in general, improved the aileron characteristics over those with the flap retracted. The most promising arrangement of full-span split flap and plain aileron combination tested, both for high lift and lateral control, was the rectangular wing with 0.20c(sub w) deflected 60 degrees at the 0.90c(sub w) location with 0.10c(sub w) semispan ailerons.

  20. Flight Tests of Modifications to Improve the Aileron Control Characteristics of a North American XP-51 Airplane (AC No. 41-38)

    NASA Technical Reports Server (NTRS)

    Hoover, Herbert H.

    1942-01-01

    Investigations were undertaken to improve the ailerons of a P-51 fighter so as to obtain greater effectiveness without increasing the stick forces. Modifications consisted of increasing the deflection range of the aileron to 70 percent and changing the original concave section to a thick section with beveled trailing edge. Results of the modified ailerons showed an increase in effectiveness over the original aileron of 70 percent at low speed and 55 percent at high speeds.

  1. Flight Investigation of the Effectiveness of an Automatic Aileron Trim Control Device for Personal Airplanes

    NASA Technical Reports Server (NTRS)

    Phillips, William H; Kuehnel, Helmut A; Whitten, James B

    1957-01-01

    A flight investigation to determine the effectiveness of an automatic aileron trim control device installed in a personal airplane to augment the apparent spiral stability has been conducted. The device utilizes a rate-gyro sensing element in order to switch an on-off type of control that operates the ailerons at a fixed rate through control centering springs. An analytical study using phase-plane and analog-computer methods has been carried out to determine a desirable method of operation for the automatic trim control.

  2. Researches on ailerons and especially on the test loads to which they should be subjected

    NASA Technical Reports Server (NTRS)

    Sabatier, J

    1927-01-01

    Aileron calculations have hitherto given greatly differing results according to different authors. It seems to be the general opinion that it is only necessary to give the ailerons such dimensions that the airplane can maneuver well, that the stresses they must undergo are relatively small, and that they are strong enough if their framework is of the order of strength as the wings to which they are attached. This article will show that the problem is really quite complex and that it should receive more attention.

  3. Charts for the Determination of Wing Torsional Stiffness Required for Specified Rolling Characteristics or Aileron Reversal Speed

    NASA Technical Reports Server (NTRS)

    Pearson, Henry A; Aiken, William S , Jr

    1944-01-01

    A series of charts are presented by which the wing torsional stiffness required to meet a given standard of rolling effectiveness may be quickly determined. The charts may also be used to obtain quickly the aileron reversal speed and the variation of the loss in rolling effectiveness with airspeed. The charts apply to linearly tapered wings and elliptical wings of tubular-shell construction having various aspect ratios with aileron span and location of ailerons as variables. In the derivation of the charts, induced lift effects have been taken into account and the form of the wing-torsional-stiffness curve has been assumed.

  4. Analysis of Effect of Rolling Pull-Outs on Wing and Aileron Loads of a Fighter Airplane

    NASA Technical Reports Server (NTRS)

    Pearson, Henry A.; Aiken, William S.

    1946-01-01

    An analysis was made to determine the effect of rolling pull-out maneuvers on the wing and aileron loads of a typical fighter airplane, the P-47B. The results obtained indicate that higher loads are imposed upon wings and ailerons because of the rolling pull-out maneuver, than would be obtained by application of the loading requirements to which the airplane was designed. An increase of 102 lb or 15 percent of wing weight would be required if the wing were designed for rolling pull-out maneuver. It was also determined that the requirements by which the aileron was originally designed were inadequate.

  5. Characteristics of a Sealed Internally Balanced Aileron from Tests of a 1/4-Scale Partial-Span Model of the Republic XF-12 Airplane in the Langley 19-Foot Pressure Tunnel

    NASA Technical Reports Server (NTRS)

    Graham, Robert R.; Martina, Albert P.; Salmi, Reino J.

    1946-01-01

    This paper presents the results of the aileron investigation and includes rolling-moment, yawing-moment, and aileron hinge-moment coefficients and pressure coefficients across the aileron-balance seal through a range of angle of attack, tab deflection, and aileron deflection with flaps neutral and deflected 20 degrees and 55 degrees. Some of the effects of wing roughness and balance seal leakage on the aileron and tab characteristics are also presented.

  6. Distribution of Pressure Over Model of the Upper Wing and Aileron of a Fokker D-VII Airplane

    NASA Technical Reports Server (NTRS)

    Fairbanks, A J

    1927-01-01

    This report describes tests made for the purpose of determining the distribution of pressure over a model of the tapered portion of the upper wing and the aileron of a Fokker D-VII Airplane. Normal pressures were measured simultaneously at 74 points distributed over the wing and aileron. Tests were made throughout the useful range of angles of attack with aileron setting ranging from -20 degrees to +20 degrees. The results are presented graphically. It was found that the pressure distribution along the chord is in general similar to that of thick tapered airfoils previously tested. The maximum resultant pressure recorded was five times the dynamic pressure. The distribution of the air load along the span may be assumed to be uniform for design purposes. Aileron displacements affect the pressures forward to the leading edge of the wing and may increase the air load on the outer portion of the wing by a considerable amount. With the wing at large angles of attack, the overhanging portion of the aileron creates usually a burble flow and therefore a large drag. The balance reduces the control stick forces at small angles of attack for all aileron displacements. At large angles of attack it does this for small displacements only. With the airplane at its maximum speed, an angle of attack of 18 degrees, and a down aileron displacement of 20 degrees, the bending moment tending to break off the overhanging portion of the aileron will be greater than that caused by a uniform static load of 35 pounds per square foot.

  7. Reynolds Number Effects on the Performance of Ailerons and Spoilers (Invited)

    NASA Technical Reports Server (NTRS)

    Mineck, R. E.

    2001-01-01

    The influence of Reynolds number on the performance of outboard spoilers and ailerons was investigated on a generic subsonic transport configuration in the National Transonic Facility over a chord Reynolds number range from 3 to 30 million and a Mach number range from 0.70 to 0.94. Spoiler deflection angles of 0, 10, and 20 degrees and aileron deflection angles of -10, 0, and 10 degrees were tested. Aeroelastic effects were minimized by testing at constant normalized dynamic pressure conditions over intermediate Reynolds number ranges. Results indicated that the increment in rolling moment due to spoiler deflection generally becomes more negative as the Reynolds number increases from 3 x 10(exp 6) to 22 x 10 (exp 6) with only small changes between Reynolds numbers of 22 x 10(exp 6) and 30 x 10(exp 6). The change in the increment in rolling moment coefficient with Reynolds number for the aileron deflected configuration is generally small with a general trend of increasing magnitude with increasing Reynolds number.

  8. Aileron and Krueger nose flap effectiveness measured on an oblique wing

    NASA Technical Reports Server (NTRS)

    Hopkins, E. J.; Lovette, G. H.

    1977-01-01

    The effects that deflection of conventional ailerons have on the lateral/directional characteristics of an oblique wing mounted on top of a body of revolution were measured. The wing had an aspect ratio of 6 (based on the unswept wing span) and was tested at various sweep angles ranging from 0 deg to 60 deg. Krueger nose flaps mounted on drooped-nose flaps were investigated on the downstream wing panel (for sweep angles of 45 deg and 60 deg) in an attempt to create more symmetrical spanwise wing stalling at high lift coefficients. The tests were conducted over a Mach number range of 0.25 to 1.4 and an angle-of-attack range from -3 deg to 28 deg. With the oblique wing in the swept position, considerable difference in the aileron effectiveness was measured for positive or negative differential aileron deflections. With the wing swept 45 deg at a Mach number of 0.8 and above, an extension of the span of the Krueger nose flaps on the downstream wing panel did not improve the linearity of the pitching-, rolling-, and yawing-moment curves.

  9. Force and pressure tests of the GA(W)-1 airfoil with a 20% aileron and pressure tests with a 30% Fowler flap

    NASA Technical Reports Server (NTRS)

    Wentz, W. H., Jr.; Seetharam, H. C.; Fiscko, K. A.

    1977-01-01

    Wind tunnel force and pressure tests were conducted for the GA(W)-1 airfoil equipped with a 20% aileron, and pressure tests were conducted with a 30% Fowler flap. All tests were conducted at a Reynolds number of 2.2 and a Mach number of 0.13. The aileron provides control effectiveness similar to ailerons applied to more conventional airfoils. Effects of aileron gaps from 0% to 2% chord were evaluated, as well as hinge moment characteristics. The aft camber of the GA(W)-1 section results in a substantial up-aileron moment, but the hinge moments associated with aileron deflection are similar to other configurations. Fowler flap pressure distributions indicate that unseparated flow is achieved for flap settings up to 40 deg., over a limited angle of attack range. Theoretical pressure distributions compare favorably with experiments for low flap deflections, but show substantial errors at large deflections.

  10. Performance and power regulation characteristics of two aileron-controlled rotors and a pitchable tip-controlled rotor on the Mod-O turbine

    NASA Technical Reports Server (NTRS)

    Corrigan, Robert D.; Ensworth, Clinton B. F., III; Miller, Dean R.

    1987-01-01

    Tests were conducted on the DOE/NASA mod-0 horizontal axis wind turbine to compare and evaluate the performance and the power regulation characteristics of two aileron-controlled rotors and a pitchable tip-controlled rotor. The two aileron-controlled rotor configurations used 20 and 38 percent chord ailerons, while the tip-controlled rotor had a pitchable blade tip. The ability of the control surfaces to regulate power was determined by measuring the change in power caused by an incremental change in the deflection angle of the control surface. The data shows that the change in power per degree of deflection angle for the tip-controlled rotor was four times the corresponding value for the 2- percent chord ailerons. The root mean square power deviation about a power setpoint was highest for the 20 percent chord aileron, and lowest for the 38 percent chord aileron.

  11. Measurements in Flight of the Lateral-Control Characteristics of an Airplane Equipped with Full-Span Zap Flaps and Simple Circular-Arc-Type Ailerons

    NASA Technical Reports Server (NTRS)

    Christophersen, Don R.; Spahr, J. Richard

    1944-01-01

    Flight tests were conducted on the OS2U-2 seaplane with simple circular-arc-type ailerons directly connected to the actuating torque tube. Two aileron test installations were made, differing only in the inclination of the projecting surface with the wing's upper surface. The lateral-control characteristics of the airplane were determined from data obtained in stalls and rudder-fixed aileron rolls. The revised ailerons were deficient in maximum rolling effectiveness, but were capable of controlling the rolling tendencies of the airplane near the stall.

  12. Wind-Tunnel Investigation of Wings with Ordinary Ailerons and Full-Span External-Airfoil Flaps

    NASA Technical Reports Server (NTRS)

    Platt, Robert C; Shortal, Joseph A

    1937-01-01

    Report presents an investigation carried out in the NACA 7- by 10-foot wind tunnel of an NACA 23012 airfoil equipped, first, with a full-span NACA 23012 external-airfoil flap having a chord 0.20 of the main airfoil chord and with a full-span aileron with a chord 0.12 of the main airfoil chord on the trailing edge of the main airfoil and equipped second, with a 0.30-chord full-span NACA 23012 external-airfoil flap and a 0.13-chord full-span aileron. The results are arranged in three groups, the first two of which deal with the airfoil characteristics of the two airfoil-flap combinations and with the internal-control characteristics of the airfoil-flap-aileron combinations. The third group of tests deals with several means for balancing ailerons mounted on a special large-chord NACA 23012 external-airfoil flap. The tests included an ordinary aileron, a curtained-nose balance, a frise balance, and a tab.

  13. A general method for the layout of ailerons and elevators of gliders and motorplanes

    NASA Technical Reports Server (NTRS)

    Hiller, M. H.

    1979-01-01

    A method is described which allows the layout of the spatial driving mechanism of the aileron for a glider or a motorplane to be performed in a systematic manner. In particular, a prescribed input-output behavior of the mechanism can be realized by variation of individual parameters of the spatial four-bar mechanisms which constitute the entire driving mechanism. By means of a sensitivity analysis, a systematic choice of parameters is possible. At the same time the forces acting in the mechanism can be limited by imposing maximum values of the forces as secondary conditions during the variation process.

  14. Turbulence model evaluation for the prediction of flows over a supercritical airfoil with deflected aileron at high Reynolds number

    NASA Technical Reports Server (NTRS)

    Londenberg, W. K.

    1993-01-01

    Navier-Stokes solutions about a supercritical airfoil with aileron deflection have been computed using the CFL3D code coupled with the Baldwin-Lomax, Johnson-King, Baldwin-Barth, and Spalart-Allmaras turbulence models. Computations were made at a Mach number of 0.716 and chord Reynolds numbers of 5, 15, and 25 million. The airfoil was analyzed with both 0 deg and 2 deg (TED) aileron deflections. Comparisons over a range of angles-of-attack showed that solutions obtained using the Baldwin-Barth turbulence model presented the best agreement with experimental pressures and sectional lift coefficients. However, Reynolds number trends in sectional lift coefficient and in aileron effectiveness were not predicted consistently.

  15. Wind-tunnel research comparing lateral control devices, particularly at high angles of attack I : ordinary ailerons on rectangular wings

    NASA Technical Reports Server (NTRS)

    Weick, Fred E; Wenzinger, Carl J

    1933-01-01

    This report is the first in a series in which it is intended to compare the relative merits of all ordinary and some special forms of ailerons and other lateral control devices in regard to their effect on lateral controllability, lateral stability, and airplane performance. The comparisons are based on wind-tunnel test data, all the control devices being fitted to model wings having the same span, area, and airfoil section, and being subjected to the same series of force and rotation tests. The results are given for five different aileron movements: one with equal up-and-down deflection, one with average and one with extreme differential motion, one with upward deflection only, and one with the ailerons arranged to float with respect to the wing.

  16. An Aileron Flutter Experiment and Analysis Using Semi-Span Model for the Small Supersonic Experimental Aircraft

    NASA Astrophysics Data System (ADS)

    Saitoh, Kenichi; Tamayama, Masato; Kikuchi, Takao; Machida, Shigeru; Nakamichi, Jiro

    This paper reports a wind-tunnel experiment and analysis that have been conducted under the National Experimental Airplane for Supersonic Transports (NEXST-1) project of JAXA. In order to perform the flight experiment, the design of the vehicle was examined from the stand point of aeroelasticity. The aileron buzz as well as flutter was of much concern for its aileron system on the main wing. Therefore, both wind-tunnel test and analysis were carried out by using a semi-span model with fuselage. Although the buzz was not observed in the test, damping responses of the aileron rotation mode were obtained. Critical damping was observed in supersonic flow, that meant a buzz could occur in ``region C'' of Lambourne's classification. Linear unsteady aerodynamic analysis is applicable to this type of buzz and the characteristics of the buzz of the model is discussed.

  17. Effect of Aspect Ratio on the Low-Speed Lateral Control Characteristics of Untapered Low-Aspect-Ratio Wings Equipped with Flap and with Retractable Ailerons

    NASA Technical Reports Server (NTRS)

    Fischel, Jack; Naeseth, Rodger L; Hagerman, John R; O'Hare, William M

    1952-01-01

    A low-speed wind-tunnel investigation was made to determine the lateral control characteristics of a series of untapered low-aspect-ratio wings. Sealed flap ailerons of various spans and spanwise locations were investigated on unswept wings of aspect ratios 1.13, 1.13, 4.13, and 6.13; and various projections of 0.60-semispan retractable ailerons were investigated on the unsweptback wings of aspect ratios 1.13, 2.13, and 4.13 and on a 45 degree sweptback wing. The retractable ailerons investigated on the unswept wings spanned the outboard stations of each wing; whereas the plain and stepped retractable ailerons investigated on the sweptback wing were located at various spanwise stations. Design charts based on experimental results are presented for estimating the flap aileron effectiveness for low-aspect-ratio, untapered, unswept.

  18. Failure Analysis of T-38 Aircraft Burst Hydraulic Aileron Return Line

    NASA Technical Reports Server (NTRS)

    Martinez, J. E.; Figert, J. D.; Paton, R. M.; Nguyen, S. D.; Flint, A.

    2012-01-01

    During maintenance troubleshooting for fluctuating hydraulic pressures, a technician found that a right hand aileron return line, on the flight hydraulic side, was ruptured (Fig. 1, 2). This tubing is part of the Hydraulic Flight Control Aileron Return Reducer to Aileron Manifold and is suspected to be original to the T-38 Talon trainer aircraft. Ailerons are small hinged sections on the outboard portion of a wing used to generate rolling motion thereby banking the aircraft. The ailerons work by changing the effective shape of the airfoil of the outer portion of the wing [1]. The drawing, Northrop P/N 3-43033-55 (6/1960), specifies that the line is made from 0.375 inch OD, aluminum 5052-0 tubing with a 0.049 inch wall thickness. WW-T-787 requires the tube shall be seamless and uniform in quality and temper [2]. The test pressure for this line is 3000 psi, and the operational pressure for this line is estimated to be between 45 psi and 1500 psi based on dynamic loading during flight. Examination of the fracture surface found evidence of arrest bands originating on the inner diameter (Fig 3). Ductile dimples are observed on the tube fractures (Fig. 4). The etched cross-section revealed thinning and work-hardening in the burst region (Fig. 5). The wall thickness just outside the work-hardened fracture region measured 0.035". Barlow's Formula: P = 2St/D, where P is burst pressure, S is allowable stress, t is wall thickness and D is the outer diameter of tube. Using the ultimate tensile strength of 28 ksi and a measured wall thickness of 0.035 inches at burst, P = 5.2 ksi (burst pressure). Using the yield of 13 ksi (YS) for aluminum 5052-0, plastic deformation will happen at P = 2.4 ksi suggesting plastic deformation occurred at a proof pressure of 3.0 ksi. Conclusion: The burst resulted from high stress, low-cycle fatigue. Evidence of arrest bands originating on the inner diameter. Fracture is predominately shear dimples, characteristic of high load ductile fractures

  19. Comparative wind tunnel tests of NACA 23024 airfoils with several aileron and spoiler configurations

    NASA Technical Reports Server (NTRS)

    Wentz, W. H., Jr.; Snyder, M. H.

    1995-01-01

    This paper reviews research efforts at Wichita State University sponsored by NASA Lewis Research Center to design and evaluate aerodynamic braking devices which will be smaller and lighter than full-chord blade pitch control. Devices evaluated include a variety of aileron configurations, and spoilers located at both trailing edge and near the leading edge. The paper discusses analytical modeling, wind tunnel tests, and for some configurations, full-scale rotor tests. Current designs have not provided adequate control power at high angles of attack (low tip-speed-ratios). The reasons for these limitations are discussed. Analysis and wind tunnel test data indicate that several options are available to the designer to provide aerodynamic slowdown without full-chord pitch control. Three options are suggested; adding venting in front of the control surface hingeline, using spoilers located near the leading edge, and using a two-piece control combining downward deflection inboard with upward deflection outboard.

  20. Rapid non-contact inspection of composite ailerons using air-coupled ultrasound

    NASA Astrophysics Data System (ADS)

    Panda, Rabi Sankar; Karpenko, Oleksii; Udpa, Lalita; Haq, Mahmoodul; Rajagopal, Prabhu; Balasubramaniam, Krishnan

    2016-02-01

    This paper demonstrates an approach for rapid non-contact air-coupled ultrasonic inspection of composite ailerons with complex cross-sectional profile including thickness changes, curvature and the presence of a number of stiffeners. Low-frequency plate guided ultrasonic modes are used in B-scan mode for the measurements in pitch-catch mode. Appropriate probe holder angles suitable for generating and receiving lower order guided wave modes are discussed. Different embodiments of the pitch-catch tandem positions along and across stiffener and curved regions of the test sample enable a rapid test campaign capturing the feature-rich sample profile. Techniques to distinguish special features in the stiffener are presented.

  1. Wind-Tunnel Investigation of the Effects of Profile Modification and Tabs on the Characteristics of Ailerons on a Low-Drag Airfoil

    NASA Technical Reports Server (NTRS)

    Crane, Robert M; Holtzclaw, Ralph W

    1944-01-01

    An investigation has been made to determine the effect of control-surface profile modifications on the aerodynamic characteristics of an NACA low-drag airfoil equipped with a 0.20-chord and a 0.15-chord aileron. Tab characteristics have been obtained for 0.20-aileron chord tabs on two of the 0.20-chord ailerons. Basic data are presented from which the effect of tabs can be calculated for specific cases. The data are sufficient for the solution of problems of fixed tabs with a differential linkage, as well as simple and spring-linked balancing tabs.

  2. Investigation of spoiler ailerons for use as speed brakes or glide-path controls on two NACA 65-series wings equipped with full-span slotted flaps

    NASA Technical Reports Server (NTRS)

    Fischel, Jack; Watson, James M

    1951-01-01

    A wind-tunnel investigation was made to determine the characteristics of spoiler ailerons used as speed brakes or glide-path controls on an NACA 65-210 wing and an NACA 65-215 wing equipped with full-span slotted flaps. Several plug aileron and retractable-aileron configurations were investigated on two wing models with the full-span flaps retracted and deflected. Tests were made at various Mach numbers between 0.13 and 0.71. The results of this investigation have indicated that the use of plug or retractable ailerons, either alone or in conjunction with wing flaps, as speed brakes or glide-path controls is feasible and very effective.

  3. Effect of Variation of Chord and Span of Ailerons on Rolling and Yawing Moments at Several Angles of Pitch

    NASA Technical Reports Server (NTRS)

    Heald, R H; Strother, D H; Monish, B H

    1931-01-01

    This report presents the results of an extension to higher angles of attack of the investigation of the rolling and yawing moments due to ailerons of various chords and spans on two airfoils having the Clark Y and U. S. A. 27 wings. The measurements were made at various angles of pitch but at zero angle of roll and yaw, the wing chord being set at an angle of +4 degrees to the fuselage axis. In the case of the Clark Y airfoil the measurements have been extended to a pitch angle of 40 degrees, using ailerons of span equal to 67 per cent of the wing semispan and chord equal to 20 and 30 per cent of the wing chord. The work was conducted on wing models of 60-inch span and 10-inch chord.

  4. Method for calculating lift distributions for unswept wings with flaps or ailerons by use of nonlinear section lift data

    NASA Technical Reports Server (NTRS)

    Sivells, James C; Westrick, Gertrude C

    1952-01-01

    A method is presented which allows the use of nonlinear section lift data in the calculation of the spanwise lift distribution of unswept wings with flaps or ailerons. This method is based upon lifting line theory and is an extension to the method described in NACA rep. 865. The mathematical treatment of the discontinuity in absolute angle of attack at the end of the flap or aileron involves the use of a correction factor which accounts for the inability of a limited trigonometric series to represent adequately the spanwise lift distribution. A treatment of the apparent discontinuity in maximum section lift coefficient is also described. Simplified computing forms containing detailed examples are given for both symmetrical and asymmetrical lift distributions. A few comparisons of calculated characteristics with those obtained experimentally are also presented.

  5. Bearing system

    DOEpatents

    Kapich, Davorin D.

    1987-01-01

    A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

  6. Wind-tunnel research comparing lateral control devices, particularly at high angles of attack V : spoilers and ailerons on rectangular wings

    NASA Technical Reports Server (NTRS)

    Weick, Fred E; Shortal, Joseph A

    1933-01-01

    This report covers the fifth of a series of systematic investigations in which lateral control devices are compared with particular reference to their effectiveness at high angles of attack. The present report deals with tests of spoilers and ordinary ailerons on rectangular Clark y wing models. In an effort to obtain satisfactory control throughout the entire angle-of-attack range that can be maintained in flight, various spoilers were tested in combination with two sizes of previously tested ordinary ailerons - one of average proportions and the other short and wide. In addition, one large spoiler was tested alone. It was found that when ailerons and spoilers are used together the full effect of both is not obtained if the spoilers are located directly in front of the ailerons. With the proper combination of spoiler and aileron, however, it is possible to obtain satisfactory rolling control up to high angles of attack (15 degrees to 20 degrees), together with favorable yawing moments and small control forces. A moderate amount of rolling control with favorable yawing moments and small control forces was obtained with the large spoiler alone.

  7. Wind tunnel tests of the GA(W)-2 airfoil with 20% aileron, 25% slotted flap, 30% Fowler flap and 10% slot-lip spoiler

    NASA Technical Reports Server (NTRS)

    Wentz, W. H., Jr.

    1977-01-01

    Two dimensional wind tunnel tests were conducted for the GA(W)-2 airfoil section with: 20% aileron, 25% slotted flap; 30% Fowler flap, and 10% slot-lip spoiler. All tests were conducted at a Reynolds number of 2,200,000 and a Mach Number of 0.13. In addition to force measurements, tuft studies were conducted for the slotted and Fowler flap configurations. Aileron and spoiler hinge moments were obtained by integration of surface pressure measurements. Tests results show that a value of 3.82 was obtained with 30% Fowler flap. Aileron control effectiveness and hinge moments were similar to other airfoils. The slot-lip spoiler provided powerful, positive roll control at all flap settings.

  8. Wind tunnel force and pressure tests of a 21% thick general aviation airfoil with 20% aileron, 25% slotted flap and 10% slot-lip spoiler

    NASA Technical Reports Server (NTRS)

    Wentz, W. H., Jr.; Fiscko, K. A.

    1979-01-01

    Force and surface pressure distributions were measured for the 21% LS(1)-0421 modified airfoil fitted with 20% aileron, 25% slotted flap and 10% slot lip spoiler. All tests were conducted at a Reynolds number of 2.2 x 10 to the 6th power and a Mach number of 0.13. The lift, drag, pitching moments, control surface normal force and hinge moments, and surface pressure distributions are included in the results. Incremental performance of flap and aileron are discussed and compared to the GA(W)-2 airfoil. Spoiler control which shows a slight reversal tendency at high alpha, is examined.

  9. Wind-Tunnel Tests to Determine Aileron Characteristics of the McDonnell XFD-1 Airplane, TED No. NACA 23102

    NASA Technical Reports Server (NTRS)

    Yates, Campbell C.; Schneiter, Leslie E.

    1946-01-01

    Tests were performed on a partial span of the wing of a McDonnell XFD-1 airplane to determine a combination of sealed internal balance and spring-tab stiffness for the aileron that would give satisfactory stick-force characteristics for the airplane. Two sealed internal balances were tested in combination with spring tabs of various stiffnesses. One of the combinations was tested at several speeds to determine the variation of stick force with speed. Estimates, based on the results of the tests, indicate that for this airplane any reduction of stick force by use of the spring tab reduces the helix angle pb/2V below the required value of 0.09. The estimates show that, of the configurations tested, the most satisfactory combination for obtaining a stick force of 30 pounds at 300 miles per hour indicated airspeed is a 0.48-chord internal balance in combination with a spring-tab stiffness of 500 pounds per inch. With this combination, a wing-tip helix angle of 0.078 is estimated. Stick-force curves for all configurations show a rapid increase in stick force above approximately 20 deg. total aileron deflection.

  10. Wind tunnel research concerning lateral control devices, particularly at high angles of attack VII : Handley Page tip and full-span slots with ailerons and spoilers

    NASA Technical Reports Server (NTRS)

    Weick, Fred E; Wenzinger, Carl J

    1933-01-01

    Tests were made with ordinary ailerons and different sizes of spoilers on rectangular Clark Y wing models with Handley Page tip and full span slots. The tests showed the effect of the control devices on the general performance of the wings as well as on the lateral control and lateral stability characteristics.

  11. A compilation of the pressures measured on a wing and aileron with various amounts of sweep in the Langley 8-foot high-speed tunnel

    NASA Technical Reports Server (NTRS)

    Whitcomb, Richard T

    1948-01-01

    A compilation is made in tabular form of all the pressures measured on a thin high-aspect-ratio wing and aileron with no sweep and with 30 degree and 45 degree of sweepback and sweepforward at high subsonic Mach numbers in the Langley 8-foot high-speed tunnel.

  12. Wind tunnel research comparing lateral control devices, particularly at high angles of attack VIII : straight and skewed ailerons on wings with rounded tips

    NASA Technical Reports Server (NTRS)

    Weick, Fred E; Shortal, Joseph A

    1933-01-01

    Tests showed the effect of the ailerons and the tip shapes on the general performance of the wing, as well as on the lateral control and stability characteristics. The hinge moments were not measured but the approximate values are given in the first report of the series.

  13. Wind tunnel investigation of the aerodynamic characteristics of symmetrically deflected ailerons of the F-8C airplane. [conducted in the Langley 8-foot transonic pressure tunnel

    NASA Technical Reports Server (NTRS)

    Gera, J.

    1977-01-01

    A .042-scale model of the F-8C airplane was investigated in a transonic wind tunnel at high subsonic Mach numbers and a range of angles of attack between-3 and 20 degrees. The effect of symmetrically deflected ailerons on the longitudinal aerodynamic characteristics was measured. Some data were also obtained on the lateral control effectiveness of asymmetrically deflected horizontal tail surfaces.

  14. THRUST BEARING

    DOEpatents

    Heller, P.R.

    1958-09-16

    A thrust bearing suitable for use with a rotor or blower that is to rotate about a vertical axis is descrihed. A centrifagal jack is provided so thnt the device may opernte on one hearing at starting and lower speeds, and transfer the load to another bearing at higher speeds. A low viscosity fluid is used to lubricate the higher speed operation bearing, in connection with broad hearing -surfaces, the ability to withstand great loads, and a relatively high friction loss, as contraated to the lower speed operatio;n bearing which will withstand only light thrust loads but is sufficiently frictionfree to avoid bearing seizure during slow speed or startup operation. An axially aligned shaft pin provides the bearing surface for low rotational speeds, but at higher speed, weights operating against spring tension withdraw nthe shaft pin into the bearing proper and the rotor shaft comes in contact with the large bearing surfaces.

  15. Simulator results of an F-14A airplane utilizing an aileron-rudder interconnect during carrier approaches and landings

    NASA Technical Reports Server (NTRS)

    Kelly, W. W.; Brown, P. W.

    1980-01-01

    A piloted simulator study was conducted to evaluate an aileron rudder interconnect (ARI) control system for the F-14A airplane in the landing configuration. Effects on pilot performance and handling characteristics were investigated. Two ARI configurations were tested and compared to the standard F-14 fleet control system. A nonlinear aerodynamic model of the F-14 was used in conjunction with a six degree of freedom motion base simulator. The evaluation task, which utilized three subject pilots, consistent of a night carrier approach and landing. Both ARI configurations produced improved pilot performance and pilot ratings when compared to the standard control system. Sideslip due to adverse yaw as considerably reduced by the ARI systems and heading control was more stable and precise. Lateral deviation from centerline was reduced during the approach and lateral touchdown dispersion on the carrier deck was reduced with the ARI control systems.

  16. Pressure Distributions for the GA(W)-2 Airfoil with 20% Aileron, 25% Slotted Flap and 30% Fowler Flap

    NASA Technical Reports Server (NTRS)

    Wentz, W. H., Jr.; Fiscko, K. A.

    1978-01-01

    Surface pressure distributions were measured for the 13% thick GA(W)-2 airfoil section fitted with 20% aileron, 25% slotted flap and 30% Fowler flap. All tests were conducted at a Reynolds number of 2.2 x 10 to the 6th power and a Mach number of 0.13. Pressure distribution and force and moment coefficient measurements are compared with theoretical results for a number of cases. Agreement between theory and experiment is generally good for low angles of attack and small flap deflections. For high angles and large flap deflections where regions of separation are present, the theory is inadequate. Theoretical drag predictions are poor for all flap-extended cases.

  17. The effectiveness of vane-aileron excitation in the experimental determination of flutter speed by parameter identification

    NASA Technical Reports Server (NTRS)

    Nissim, Eli

    1990-01-01

    The effectiveness of aerodynamic excitation is evaluated analytically in conjunction with the experimental determination of flutter dynamic pressure by parameter identification. Existing control surfaces were used, with an additional vane located at the wingtip. The equations leading to the identification of the equations of motion were reformulated to accommodate excitation forces of aerodynamic origin. The aerodynamic coefficients of the excitation forces do not need to be known since they are determined by the identification procedure. The 12 degree-of-freedom numerical example treated in this work revealed the best wingtip vane locations, and demonstrated the effectiveness of the aileron-vane excitation system. Results from simulated data gathered at much lower dynamic pressures (approximately half the value of flutter dynamic pressure) predicted flutter dynamic pressures with 2-percent errors.

  18. Journal bearing

    DOEpatents

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  19. Grizzly bear

    USGS Publications Warehouse

    Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.

    2003-01-01

    The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

  20. Polar Bear

    USGS Publications Warehouse

    Amstrup, S.D.; DeMaster

    1988-01-01

    Polar bears are long-lived, late-maturing carnivores that have relatively low rates of reproduction and natural mortality. Their populations are susceptible to disturbance from human activities, such as the exploration and development of mineral resources or hunting. Polar bear populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.

  1. Calculations on the forces and moments for an oscillating wing-aileron combination in two-dimensional potential flow at sonic speed

    NASA Technical Reports Server (NTRS)

    Nelson, Herbert C; Berman, Julian H

    1953-01-01

    The linearized theory for compressible unsteady flow is used, as suggested in recent contributions to the subject, to obtain the velocity potential and the lift and moment for a thin harmonically oscillating, two-dimensional wing-aileron combination moving at sonic speed. The velocity potential is derived by considering the sonic case as the limit of the linearized supersonic theory. From the velocity potential explicit expressions for the lift and moment are developed for vertical translation and pitching of the wing and rotation of the aileron. The sonic results are compared and found to be consistent with previously obtained subsonic and supersonic results. Several figures are presented showing the variation of lift and moment with reduced frequency and Mach number and the influence of Mach number on some cases of bending-torsion flutter.

  2. Method for calculating the rolling and yawing moments due to rolling for unswept wings with or without flaps or ailerons by use of nonlinear section lift data

    NASA Technical Reports Server (NTRS)

    Martina, Albert P

    1954-01-01

    The methods of NACA reports 865 and 1090 have been applied to the calculation of the rolling-moment and yawing-moment coefficients due to rolling for unswept wings with or without flaps or ailerons. The methods are based on lifting-line theory and allow the use of nonlinear section lift data. The method presented in this report permits calculations to be made somewhat beyond maximum lift for wings having no twist or continuous twist and employing airfoil sections which do not display large discontinuities in the lift curves. Calculations can be made up to maximum lift for wings with discontinuous twist such as that produced by partial-span flaps or ailerons, or both. Two calculated examples are presented in simplified computing forms in order to illustrate the procedures involve.

  3. Method for calculating the rolling and yawing moments due to rolling for unswept wings with or without flaps or ailerons by use of nonlinear section lift data

    NASA Technical Reports Server (NTRS)

    Martina, Albert P

    1953-01-01

    The methods of NACA Reports 865 and 1090 have been applied to the calculation of the rolling- and yawing-moment coefficients due to rolling for unswept wings with or without flaps or ailerons. The methods allow the use of nonlinear section lift data together with lifting-line theory. Two calculated examples are presented in simplified computing forms in order to illustrate the procedures involved.

  4. Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    1996-01-01

    AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

  5. Foil bearings

    NASA Technical Reports Server (NTRS)

    Elrod, David A.

    1993-01-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  6. Seismic bearing

    NASA Astrophysics Data System (ADS)

    Power, Dennis

    2009-05-01

    Textron Systems (Textron) has been using geophones for target detection for many years. This sensing capability was utilized for detection and classification purposes only. Recently Textron has been evaluating multiaxis geophones to calculate bearings and track targets more specifically personnel. This capability will not only aid the system in locating personnel in bearing space or cartesian space but also enhance detection and reduce false alarms. Textron has been involved in the testing and evaluation of several sensors at multiple sites. One of the challenges of calculating seismic bearing is an adequate signal to noise ratio. The sensor signal to noise ratio is a function of sensor coupling to the ground, seismic propagation and range to target. The goals of testing at multiple sites are to gain a good understanding of the maximum and minimum ranges for bearing and detection and to exploit that information to tailor sensor system emplacement to achieve desired performance. Test sites include 10A Site Devens, MA, McKenna Airfield Ft. Benning, GA and Yuma Proving Ground Yuma, AZ. Geophone sensors evaluated include a 28 Hz triax spike, a 15 Hz triax spike and a hybrid triax spike consisting of a 10 Hz vertical geophone and two 28 Hz horizontal geophones. The algorithm uses raw seismic data to calculate the bearings. All evaluated sensors have triaxial geophone configuration mounted to a spike housing/fixture. The suite of sensors also compares various types of geophones to evaluate benefits in lower bandwidth. The data products of these tests include raw geophone signals, seismic features, seismic bearings, seismic detection and GPS position truth data. The analyses produce Probability of Detection vs range, bearing accuracy vs range, and seismic feature level vs range. These analysis products are compared across test sites and sensor types.

  7. An Investigation of the Aerodynamic Characteristics of an 0.08-Scale Model of the Chance Vought XF7U-1 Airplane in the Langley High-Speed 7- by 10-Foot Tunnel. Part IV - Aileron Characteristics TED No. NACA DE308. Part 4; Aileron Characteristics, TED No. NACA DE308

    NASA Technical Reports Server (NTRS)

    Goodson, Kenneth W.; Myers, Boyd C., II

    1947-01-01

    Tests have been conducted in the Langley high-speed 7- by 10-foot tunnel over a Mach number range from 0.40 to 0.91 to determine the stability and control characteristics of an 0.08-scale model of the Chance Vought XF7U-1 airplane. The aileron characteristics of the complete model are presented in the present report with a very limited analysis of the results.

  8. System for testing bearings

    NASA Astrophysics Data System (ADS)

    Gibson, John C.

    1993-07-01

    Disclosed here is a system for testing bearings wherein a pair of spaced bearings provides support for a shaft on which is mounted a bearing to be tested, this bearing being mounted in a bearing holder spaced from and in alignment with the pair of bearings. The bearing holder is provided with an annular collar positioned in an opening in the bearing holder for holding the bearing to be tested. A screw threaded through the bearing holder into engagement with the annular collar can be turned to force the collar radially out of alignment with the pair of bearings to apply a radial load to the bearing.

  9. CUSHIONED BEARING

    DOEpatents

    Rushing, F.C.

    1960-09-01

    A vibration damping device effective to dampen vibrations occurring at the several critical speeds encountered in the operation of a high-speed centrifuge is described. A self-centering bearing mechanism is used to protect both the centrifuge shaft and the damping mechanism. The damping mechanism comprises spaced-apant, movable, and stationary sleeve members arranged concentrically of a rotating shaft with a fluid maintained between the members. The movable sleeve member is connected to the shaft for radial movement therewith.

  10. Tooling Converts Stock Bearings To Custom Bearings

    NASA Technical Reports Server (NTRS)

    Fleenor, E. N., Jr.

    1983-01-01

    Technique for reworking stock bearings saves time and produces helicopter-rotor bearings ground more precisely. Split tapered ring at one end of threaded bolt expands to hold inside of inner race bearing assembly; nut, at other end of bolt, adjusts amount of spring tension. Piece of hardware grasps bearing firmly without interfering with grinding operation. Operation produces bearing of higher quality than commercially available bearings.

  11. Comparison of pressure distributions on model and full-scale NACA 64-621 airfoils with ailerons for wind turbine application

    SciTech Connect

    Gregorek, G.M.; Kuniega, R.J.; Nyland, T.W.

    1988-04-01

    The aerodynamic similarity between a small (4-in. chord) wind tunnel model and a full-scale wind turbine blade (24-ft tip section with a 36-in. chord) was evaluated by comparing selected pressure distributions around the geometrically similar cross sections. The airfoils were NACA 64-621 sections, including trailing-edge ailerons with a width equal to 38 percent of the airfoil chord. The model airfoil was tested in the OSU 6- by 12-In. High Reynolds Number Wind Tunnel; the full-scale blade section was tested in the NASA Langley Research Center 30- by 60-Ft Subsonic Wind Tunnel. The model airfoil contained 61 pressure taps connected by embedded tubes to pressure transducers. A belt containing 29 pressure taps was fixed to the full-scale section at midspan to obtain surface pressure data. Lift coefficients were obtained by integrating pressures, and corrections were made for the three-dimensional effects of blade twist and downwash in the blade tip section. Good correlation was obtained between the results of the two different experimental methods for angles of attack from -4/degree/ to 36/degree/ and aileron deflections from 0/degree/ to 90/degree/. 4 refs., 11 figs., 1 tab.

  12. Comparison of pressure distributions on model and full-scale NACA 64-621 airfoils with ailerons for wind turbine application

    NASA Technical Reports Server (NTRS)

    Gregorek, G. M.; Kuniega, R. J.; Nyland, T. W.

    1988-01-01

    The aerodynamic similarity between a small (4-inch chord) wind tunnel model and a full-scale wind turbine blade (24-foot tip section with a 36-inch chord) was evaluated by comparing selected pressure distributions around the geometrically similar cross sections. The airfoils were NACA 64-621 sections, including trailing-edge ailerons with a width equal to 38 percent of the airfoil chord. The model airfoil was tested in the OSU 6- by 12-inch High Reynolds Number Wind Tunnel; the full-scale blade section was tested in the NASA Langley Research Center 30- by 60-foot Subsonic Wind Tunnel. The model airfoil contained 61 pressure taps connected by embedded tubes to pressure transducers. A belt containing 29 pressure taps was fixed to the full-scale section at midspan to obtain surface pressure data. Lift coefficients were obtained by integrating pressures, and corrections were made for the 3-D effects of blade twist and downwash in the blade tip section. The results of the two different experimental methods correlated well for angles of attack from minus 4 to 36 degrees and aileron reflections from 0 to 90 degrees.

  13. Fluid lubricated bearing construction

    DOEpatents

    Dunning, John R.; Boorse, Henry A.; Boeker, Gilbert F.

    1976-01-01

    1. A fluid lubricated thrust bearing assembly comprising, in combination, a first bearing member having a plain bearing surface, a second bearing member having a bearing surface confronting the bearing surface of said first bearing member and provided with at least one spiral groove extending inwardly from the periphery of said second bearing member, one of said bearing members having an axial fluid-tight well, a source of fluid lubricant adjacent to the periphery of said second bearing member, and means for relatively rotating said bearing members to cause said lubricant to be drawn through said groove and to flow between said bearing surfaces, whereby a sufficient pressure is built up between said bearing surfaces and in said well to tend to separate said bearing surfaces.

  14. Cryogenic turbopump bearing materials

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.

    1989-01-01

    Materials used for modern cryogenic turbopump bearings must withstand extreme conditions of loads and speeds under marginal lubrication. Naturally, these extreme conditions tend to limit the bearing life. It is possible to significantly improve the life of these bearings, however, by improving the fatigue and wear resistance of bearing alloys, and improving the strength, liquid oxygen compatibility and lubricating ability of the bearing cage materials. Improved cooling will also help to keep the bearing temperatures low and hence prolong the bearing life.

  15. Description of an experimental (hydrogen peroxide) rocket system and its use in measuring aileron and rudder effectiveness of a light airplane

    NASA Technical Reports Server (NTRS)

    Obryan, T. C.; Goode, M. W.; Gregory, F. D.; Mayo, M. H.

    1980-01-01

    A hydrogen peroxide fueled rocket system, which is to be used as a research tool in flight studies of stall and spin maneuvers, was installed on a light, four place general aviation airplane. The pilot controlled rocket system produces moments about either the roll or the yaw body axis to augment or oppose the aerodynamic forces and inertial moments acting on the airplane during various flight maneuvers, including the spin. These controlled moments of a known magnitude can be used in various ways to help analyze and interpret the importance of the various factors which influence airplane maneuvers. The rocket system and its installation in the airplane are described, and the results of flight rests used to measure rudder and aileron effectiveness at airspeeds above the stall are presented. These tests also serve to demonstrate the operational readiness of the rocket system for future research operations.

  16. Restoration of bearings

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.; Hanau, H.

    1977-01-01

    Process consisting of grinding raceways to oversize but original quality condition and installing new oversize balls or bearings restores wornout ball and roller bearings to original quality, thereby doubling their operating life. Evaluations reveal process results in restoration of 90% of replaced bearings at less than 50% of new-bearing costs.

  17. Passive magnetic bearing configurations

    DOEpatents

    Post, Richard F.

    2011-01-25

    A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

  18. Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Anderson, W. J.

    1983-01-01

    Rolling element bearings are a precision, yet simple, machine element of great utility. A brief history of rolling element bearings is reviewed and the type of rolling element bearings, their geometry and kinematics, as well as the materials they are made from and the manufacturing processes they involve are described. Unloaded and unlubricated rolling element bearings, loaded but unlubricated rolling element bearings and loaded and lubricated rolling element bearings are considered. The recognition and understanding of elastohydrodynamic lubrication covered, represents one of the major development in rolling element bearings.

  19. Introduction to ball bearings

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1981-01-01

    The purpose of a ball bearing is to provide a relative positioning and rotational freedom while transmitting a load between two structures, usually a shaft and a housing. For high rotational speeds (e.g., in gyroscope ball bearings) the purpose can be expanded to include rotational freedom with practically no wear in the bearing. This condition can be achieved by separating the bearing parts with a coherent film of fluid known as an elastohydrodynamic film. This film can be maintained not only when the bearing carries the load on a shaft, but also when the bearing is preloaded to position the shaft to within micro- or nano-inch accuracy and stability. Background information on ball bearings is provided, different types of ball bearings and their geometry and kinematics are defined, bearing materials, manufacturing processes, and separators are discussed. It is assumed, for the purposes of analysis, that the bearing carries no load.

  20. High efficiency magnetic bearings

    NASA Technical Reports Server (NTRS)

    Studer, Philip A.; Jayaraman, Chaitanya P.; Anand, Davinder K.; Kirk, James A.

    1993-01-01

    Research activities concerning high efficiency permanent magnet plus electromagnet (PM/EM) pancake magnetic bearings at the University of Maryland are reported. A description of the construction and working of the magnetic bearing is provided. Next, parameters needed to describe the bearing are explained. Then, methods developed for the design and testing of magnetic bearings are summarized. Finally, a new magnetic bearing which allows active torque control in the off axes directions is discussed.

  1. Mechanical spin bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1998-01-01

    A spin bearing assembly including, a pair of mutually opposing complementary bearing support members having mutually spaced apart bearing support surfaces which may be, for example, bearing races and a set of spin bearings located therebetween. Each spin bearing includes a pair of end faces, a central rotational axis passing through the end faces, a waist region substantially mid-way between the end faces and having a first thickness dimension, and discrete side surface regions located between the waist region and the end faces and having a second thickness dimension different from the first thickness dimension of the waist region and wherein the side surface regions further have respective curvilinear contact surfaces adapted to provide a plurality of bearing contact points on the bearing support members.

  2. Axial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  3. Supertough Stainless Bearing Steel

    NASA Technical Reports Server (NTRS)

    Olson, Gregory B.

    1995-01-01

    Composition and processing of supertough stainless bearing steel designed with help of computer-aided thermodynamic modeling. Fracture toughness and hardness of steel exceeds those of other bearing steels like 440C stainless bearing steel. Developed for service in fuel and oxidizer turbopumps on Space Shuttle main engine. Because of strength and toughness, also proves useful in other applications like gears and surgical knives.

  4. 1-Way Bearing

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2003-01-01

    A one-way bearing is provided having sprags and rolling bearings both disposed between an inner and an outer race. The sprags may comprise three-dimensional sprags for preventing rotation in a non-preferential direction. The roll- ing bearings may comprise thrust rollers for transmitting axial, tilt, and radial loads between the inner and outer races.

  5. Bearings working group

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The service life of the Space Shuttle Main Engine (SSME) turbomachinery bearings was a predominant factor in engine durability and maintenance problems. Recent data has indicated that bearing life is about one order of magnitude lower than the goal of seven and one-half hours particularly those in the High Pressure Oxidizer Turbopump (HPOTP). Bearing technology, primarily cryogenic turbomachinery bearing technology, is expanded by exploring the life and performance effects of design changes; design concept changes; materials changes; manufacturing technique changes; and lubrication system changes. Each variation is assessed against the current bearing design in full scale cryogenic tests.

  6. Cryogenic Hybrid Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

    1994-01-01

    Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

  7. Bearings: Technology and needs

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.

    1982-01-01

    A brief status report on bearing technology and present and near-term future problems that warrant research support is presented. For rolling element bearings a material with improved fracture toughness, life data in the low Lambda region, a comprehensive failure theory verified by life data and incorporated into dynamic analyses, and an improved corrosion resistant alloy are perceived as important needs. For hydrodynamic bearings better definition of cavitation boundaries and pressure distributions for squeeze film dampers, and geometry optimization for minimum power loss in turbulent film bearings are needed. For gas film bearings, foil bearing geometries that form more nearly optimum film shapes for maximum load capacity, and more effective surface protective coatings for high temperature operation are needed.

  8. Bear Spray Safety Program

    USGS Publications Warehouse

    Blome, C.D.; Kuzniar, R.L.

    2009-01-01

    A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

  9. Bearing restoration by grinding

    NASA Technical Reports Server (NTRS)

    Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

    1976-01-01

    A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

  10. Extending bearing life

    SciTech Connect

    Boyer, D.

    1997-08-01

    Long-term bearing operation cannot be achieved unless proper handling, storage, installation, and maintenance procedures are followed. These factors can shorten--sometimes drastically--expected bearing service life. Failures are generally related to improper lubrication or installation and induced conditions. Most major bearing manufacturers offer technical assistance in inspection, evaluation, and reporting on bearings which have failed in service. Actual percentages associated with each failure category vary, depending on the source, but generally they are 70% from lubrication and installation, 20% from induced factors, and 10% from reaching their fatigue limit or design life. The paper describes lubricant-related failures and procedures for the correct handling, storage, installation, and maintenance.

  11. Linear magnetic bearing

    NASA Technical Reports Server (NTRS)

    Studer, P. A. (Inventor)

    1983-01-01

    A linear magnetic bearing system having electromagnetic vernier flux paths in shunt relation with permanent magnets, so that the vernier flux does not traverse the permanent magnet, is described. Novelty is believed to reside in providing a linear magnetic bearing having electromagnetic flux paths that bypass high reluctance permanent magnets. Particular novelty is believed to reside in providing a linear magnetic bearing with a pair of axially spaced elements having electromagnets for establishing vernier x and y axis control. The magnetic bearing system has possible use in connection with a long life reciprocating cryogenic refrigerator that may be used on the space shuttle.

  12. Passive Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1983-01-01

    Magnetic bearing for limited rotation devices requires no feedback control system to sense and correct shaft position. Passive Magnetic Torsion Bearing requires no power supply and has no rubbing parts. Torsion wire restrains against axial instability. Magnetic flux geometry chosen to assure lateral stability with radial restoring force that maintains alignment.

  13. Bearing servicing tool

    NASA Technical Reports Server (NTRS)

    Boyce, Rex A. (Inventor)

    1992-01-01

    A tool for removing and/or replacing bearings in situ is presented. The tool is comprised of a brace having a first end adapted to engage a first end of the bearing housing, and a second end adapted to engage a second end of the bearing housing. If the two ends of the bearing housing are different in configuration, then the respective ends of the brace are configured accordingly. An elongate guide member integral with the brace has two parts, each projecting endwise from a respective end of the brace. A removable pressure plate can be mounted on either part of the guide member for longitudinal movement therealong and has first and second ends of different configurations adapted to engage the first and second ends of the bearing. A threaded-type drive is cooperative between the guide and the pressure plate to move the pressure plate longitudinally along the guide and apply a force to the bearing, either to remove the bearing from its housing, or to emplace a new bearing in the housing.

  14. Bearing fatigue investigation 3

    NASA Technical Reports Server (NTRS)

    Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

    1982-01-01

    The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

  15. Cylindrical bearing analysis

    NASA Technical Reports Server (NTRS)

    Kleckner, R. J.; Pirvics, J.

    1981-01-01

    Program CYBEAN computes behavior of rolling-element bearings including effects of bearing geometry, shaft misalinement, and temperature. Accurate assessment is possible for various outer-ring and housing configurations. CYBEAN is structured for coordinated execution of modules that perform specific analytical tasks. It is written in FORTRAN IV for use on the UNIVAC 1100/40 computer.

  16. Arcturus and the Bears

    NASA Astrophysics Data System (ADS)

    Antonello, E.

    2009-08-01

    Arcturus is the brightest star in Bootes. The ancient Greek name Arktouros means Bear Guard. The star, however, is not close to Ursa Maior (Big She-Bear) and Ursa Minor (Little She-Bear), as the name would suggest. This curious discrepancy could be explained by the star proper motion, assuming the name Bear Guard is a remote cultural heritage. The proper motion analysis could allow us to get an insight also into an ancient myth regarding Ursa Maior. Though we cannot explain scientifically such a myth, some interesting suggestions can be obtained about its possible origin, in the context of the present knowledge of the importance of the cult of the bear both during the Palaeolithic times and for several primitive populations of modern times, as shown by the ethnological studies.

  17. OTV bearing deflection investigation

    NASA Astrophysics Data System (ADS)

    Reimer, B. L.; Diepenbrock, R. T.; Millis, M. G.

    1993-04-01

    The primary goal of the Bearing Deflectometer Investigation was to gain experience in the use of fiber optic displacement probe technology for bearing health monitoring in a liquid hydrogen turbo pump. The work specified in this Task Order was conducted in conjunction with Air Force Rocket Propulsion Laboratory Contract F04611-86-C-0010. APD conducted the analysis and design coordination to provide a displacement probe design compatible with the XLR-134 liquid hydrogen turbo pump assembly (TPA). Specifications and requirements of the bearing deflectometer were established working with Mechanical Technology Instruments, Inc. (MTI). The TPA design accommodated positioning of the probe to measure outer race cyclic deflections of the pump inlet bearing. The fiber optic sensor was installed as required in the TPA and sensor output was recorded during the TPA testing. Data review indicated that no bearing deflection signature could be differentiated from the inherent system noise. Alternate sensor installations were not investigated, but might yield different results.

  18. Touchdown Ball-Bearing System for Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Kingsbury, Edward P.; Price, Robert; Gelotte, Erik; Singer, Herbert B.

    2003-01-01

    The torque-limited touchdown bearing system (TLTBS) is a backup mechanical-bearing system for a high-speed rotary machine in which the rotor shaft is supported by magnetic bearings in steady-state normal operation. The TLTBS provides ball-bearing support to augment or supplant the magnetic bearings during startup, shutdown, or failure of the magnetic bearings. The TLTBS also provides support in the presence of conditions (in particular, rotational acceleration) that make it difficult or impossible to control the magnetic bearings or in which the magnetic bearings are not strong enough (e.g., when the side load against the rotor exceeds the available lateral magnetic force).

  19. Magnetically-controlled bearing lubrication

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F.

    1977-01-01

    Proposed magnetic-lubricant ball-bearing assembly has permanently-magnetized bearing retainer fabricated of porous material. Pores of retainer are filled with ferrolubricant. Surface tension causes retainer to deliver sufficient lubricant to nonmagnetic ball bearings.

  20. Ball Bearing Mechanics

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1981-01-01

    Load-deflection relationships for different types of elliptical contacts such as those found in a ball bearing are developed. Simplified expressions that allow quick calculations of deformation to be made simply from a knowledge of the applied load, the material properties, and the geometry of the contacting elements are presented. Ball bearings subjected to radial, thrust and combined ball loads are analyzed. A design criterion for fatigue life of ball bearings is developed. The section of a satisfactory lubricant, as well as describing systems that provide a constant flow of lubricant to the contact, is considered.

  1. Magnetic bearing update

    SciTech Connect

    Fowler, T.K.

    1995-05-25

    Stabilization of whirl instability by floppy, viscous bearing mounts is discussed and required material properties are estimated for the new tilt-whirl mode in eddy-current stabilized magnetic bearings. A relatively low Young`s modules Y {approximately} 10{sup 5} and high viscosity {zeta} {approximately} 10{sup 7} are required (both in MKS units), suggesting the need for careful mounting design. New information on periodic bearings shows that, thus far, Earshaw`s Theorem cannot be defeated by periodicity, despite the author`s earlier claims.

  2. Ball and Roller Bearings. A Teaching Reference.

    ERIC Educational Resources Information Center

    American Association for Vocational Instructional Materials, Athens, GA.

    The manual provides a subject reference for ball and roller bearings. The following topics are included: (1) bearing nomenclature, (2) bearing uses, (3) bearing capacities, (4) shop area working conditions, (5) bearing removal, (6) bearing cleaning and inspection, (7) bearing replacement, (8) bearing lubrication, (9) bearing installation, (10)…

  3. Arkansas black bear hunter survey

    USGS Publications Warehouse

    Pharris, Larry D.; Clark, Joseph D.

    1987-01-01

    Questionnaires were mailed to black bear (Ursus americanus) hunters in Arkansas following the 1980-84 bear seasons to determine participation, hunter success, and number of bears observed by hunters. Man-days of hunting to harvest a bear ranged from 148 to 671 and hunter success ranged from 0.4% to 2.2%. With the exception of 1980, number of permits issued, man-days of bear hunting, and bears harvested appear affected by hunting permit cost. 

  4. Roller bearing geometry design

    NASA Technical Reports Server (NTRS)

    Savage, M.; Pinkston, B. H. W.

    1976-01-01

    A theory of kinematic stabilization of rolling cylinders is extended and applied to the design of cylindrical roller bearings. The kinematic stabilization mechanism puts a reverse skew into the rolling elements by changing the roller taper. Twelve basic bearing modification designs are identified amd modeled. Four have single transverse convex curvature in their rollers while eight have rollers which have compound transverse curvature made up of a central cylindrical band surrounded by symmetric bands with slope and transverse curvature. The bearing designs are modeled for restoring torque per unit axial displacement, contact stress capacity, and contact area including dynamic loading, misalignment sensitivity and roller proportion. Design programs are available which size the single transverse curvature roller designs for a series of roller slopes and load separations and which design the compound roller bearings for a series of slopes and transverse radii of curvature. The compound rollers are proportioned to have equal contact stresses and minimum size. Design examples are also given.

  5. Magnetically levitated superconducting bearing

    SciTech Connect

    Weinberger, B.R.; Lynds, L. Jr.

    1993-10-26

    A magnetically levitated superconducting bearing includes a magnet mounted on a shaft that is rotatable around an axis of rotation and a Type II superconductor supported on a stator in proximity to the magnet. The superconductor is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet to produce an attractive force that levitates the magnet and supports a load on the shaft. The interaction between the superconductor and magnet also produces surface screening currents that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature. The bearing could also be constructed so the magnet is supported on the stator and the superconductor is mounted on the shaft. The bearing can be operated by cooling the superconductor to its superconducting state in the presence of a magnetic field. 6 figures.

  6. Hydrostatic bearing support

    NASA Technical Reports Server (NTRS)

    Cunningham, R. E. (Inventor)

    1977-01-01

    A hydrostatic bearing support system is provided which comprises a bearing housing having a polygonally configured outer surface which defines at least three symmetrically disposed working faces and a plurality of pressure plates, each of which is disposed relatively opposite a corresponding working face and spaced therefrom to define a gap therebetween. A hydrostatic support film is created in the gap for supporting the housing in spaced relationship to the pressure plates.

  7. Gear bearing drive

    NASA Technical Reports Server (NTRS)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  8. Deformable bearing seat

    NASA Technical Reports Server (NTRS)

    Moreman, O. S., III (Inventor)

    1977-01-01

    A deformable bearing seat is described for seating a bearing assembly in a housing. The seat includes a seating surface in the housing having a first predetermined spheroidal contour when the housing is in an undeformed mode. The seating surface is deformable to a second predetermined spherically contoured surface when the housing is in a deformed mode. The seat is particularly adaptable for application to a rotating blade and mounting ring assembly in a gas turbine engine.

  9. Load responsive hydrodynamic bearing

    DOEpatents

    Kalsi, Manmohan S.; Somogyi, Dezso; Dietle, Lannie L.

    2002-01-01

    A load responsive hydrodynamic bearing is provided in the form of a thrust bearing or journal bearing for supporting, guiding and lubricating a relatively rotatable member to minimize wear thereof responsive to relative rotation under severe load. In the space between spaced relatively rotatable members and in the presence of a liquid or grease lubricant, one or more continuous ring shaped integral generally circular bearing bodies each define at least one dynamic surface and a plurality of support regions. Each of the support regions defines a static surface which is oriented in generally opposed relation with the dynamic surface for contact with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the bearing and are integral with and located between adjacent support regions. Each of the flexing regions has a first beam-like element being connected by an integral flexible hinge with one of the support regions and a second beam-like element having an integral flexible hinge connection with an adjacent support region. A least one local weakening geometry of the flexing region is located intermediate the first and second beam-like elements. In response to application of load from one of the relatively rotatable elements to the bearing, the beam-like elements and the local weakening geometry become flexed, causing the dynamic surface to deform and establish a hydrodynamic geometry for wedging lubricant into the dynamic interface.

  10. Magnetic bearing and motor

    NASA Technical Reports Server (NTRS)

    Studer, P. A. (Inventor)

    1983-01-01

    A magnetic bearing for passively suspending a rotatable element subjected to axial and radial thrust forces is disclosed. The magnetic bearing employs a taut wire stretched along the longitudinal axis of the bearing between opposed end pieces and an intermediate magnetic section. The intermediate section is segmented to provide oppositely directed magnetic flux paths between the end pieces and may include either an axially polarized magnets interposed between the segments. The end pieces, separated from the intermediate section by air gaps, control distribution of magnetic flux between the intermediate section segments. Coaxial alignment of the end pieces with the intermediate section minimizes magnetic reluctance in the flux paths endowing the bearing with self-centering characteristics when subjected to radial loads. In an alternative embodiment, pairs of oppositely wound armature coils are concentrically interposed between segments of the intermediate section in concentric arcs adjacent to radially polarized magnets to equip a magnetic bearing as a torsion drive motor. The magnetic suspension bearing disclosed provides long term reliability without maintenance with application to long term space missions such as the VISSR/VAS scanning mirror instrument in the GOES program.

  11. Investigation of Pressurized Wave Bearings

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Dimofte, Florin

    2003-01-01

    The wave bearing has been pioneered and developed by Dr. Dimofte over the past several years. This bearing will be the main focus of this research. It is believed that the wave bearing offers a number of advantages over the foil bearing, which is the bearing that NASA is currently pursuing for turbomachinery applications. The wave bearing is basically a journal bearing whose film thickness varies around the circumference approximately sinusoidally, with usually 3 or 4 waves. Being a rigid geometry bearing, it provides precise control of shaft centerlines. The wave profile also provides good load capacity and makes the bearing very stable. Manufacturing techniques have been devised that should allow the production of wave bearings almost as cheaply as conventional full-circular bearings.

  12. Simple modeling of hydrostatic bearings

    NASA Astrophysics Data System (ADS)

    Hull, Charlie

    2014-07-01

    Hydrostatic bearings are a key component for many large telescopes due to their high load bearing capacity, stiffness and low friction. A simple technique is presented to model these bearings to understand the effects of geometry, oil viscosity, flow control, temperature, etc. on the bearings behavior.

  13. Climate Drives Polar Bear Origins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

  14. Magnetic Bearing Consumes Low Power

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1982-01-01

    Energy-efficient linear magnetic bearing maintains a precise small separation between its moving and stationary parts. Originally designed for cryogenic compressors on spacecraft, proposed magnetic bearing offers an alternative to roller or gas bearing in linear motion system. Linear noncontacting bearing operates in environments where lubricants cannot be used.

  15. Fluid lubricated bearing assembly

    DOEpatents

    Boorse, Henry A.; Boeker, Gilbert F.; Menke, John R.

    1976-01-01

    1. A support for a loaded rotatable shaft comprising in combination on a housing having a fluid-tight cavity encasing an end portion of said shaft, a thrust bearing near the open end of said cavity for supporting the axial thrust of said shaft, said thrust bearing comprising a thrust plate mounted in said housing and a thrust collar mounted on said shaft, said thrust plate having a central opening the peripheral portion of which is hermetically sealed to said housing at the open end of said cavity, and means for supplying a fluid lubricant to said thrust bearing, said thrust bearing having a lubricant-conducting path connecting said lubricant supplying means with the space between said thrust plate and collar intermediate the peripheries thereof, the surfaces of said plate and collar being constructed and arranged to inhibit radial flow of lubricant and, on rotation of said thrust collar, to draw lubricant through said path between the bearing surfaces and to increase the pressure therebetween and in said cavity and thereby exert a supporting force on said end portion of said shaft.

  16. Solving bearing overheating problems

    SciTech Connect

    Jendzurski, T.

    1995-05-08

    Overheating is a major indicator, along with vibration and noise, of an underlying problem affecting a bearing or related components. Because normal operating temperatures vary widely from one application to another, no single temperature is a reliable sign of overheating in every situation. By observing an application when it is running smoothly, a technician can establish a benchmark temperature for a particular bearing arrangement. Wide deviations from this accepted norm generally indicate troublesome overheating. The list of possible causes of over-heating ranges from out-of-round housings and oversize shaft diameters to excessive lubrication and bearing preloading. These causes fall into two major categories: improper or faulty lubrication and mechanical problems, such as incorrect fits and tolerances. These are discussed along with solutions.

  17. Radial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  18. Magnetic bearings for spacecraft

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1972-01-01

    Magnetic bearings have been successfully applied to motorized rotor systems in the multi-kilogram range, at speeds up to 1200 radians per second. These engineering models also indicated the need for continued development in specific areas to make them feasible for spacecraft applications. Significant power reductions have recently been attained. A unique magnetic circuit, combining permanent magnets with electromagnetic control, has a bidirectional forcing capability with improved current sensitivity. The multi-dimensional nature of contact-free rotor support is discussed. Stable continuous radial suspension is provided by a rotationally symmetric permanent magnet circuit. Two bearings, on a common shaft, counteract the normal instability perpendicular to the rotational axis. The axial direction is servoed to prevent contact. A new bearing technology and a new field of application for magnetics is foreseen.

  19. Partial tooth gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  20. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  1. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    1999-01-01

    Methods and apparatus are provided for a blood pump bearing system within a pump housing to support long-term high-speed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the shaft to support high speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  2. Modular gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2009-01-01

    A gearing system using modular gear bearing components. Each component is composed of a core, one or more modules attached to the core and two or more fastening modules rigidly attaching the modules to the core. The modules, which are attached to the core, may consist of gears, rollers or gear bearing components. The core orientation affects the orientation of the modules attached to the core. This is achieved via the keying arrangement of the core and the component modules that attach to the core. Such an arrangement will also facilitate the phase tuning of gear modules with respect to the core and other gear modules attached to the core.

  3. History of ball bearings

    NASA Technical Reports Server (NTRS)

    Dowson, D.; Hamrock, B. J.

    1981-01-01

    The familiar precision rolling-element bearings of the twentieth century are products of exacting technology and sophisticated science. Their very effectiveness and basic simplicity of form may discourage further interest in their history and development. Yet the full story covers a large portion of recorded history and surprising evidence of an early recognition of the advantages of rolling motion over sliding action and progress toward the development of rolling-element bearings. The development of rolling-element bearings is followed from the earliest civilizations to the end of the eighteenth century. The influence of general technological developments, particularly those concerned with the movement of large building blocks, road transportation, instruments, water-raising equipment, and windmills are discussed, together with the emergence of studies of the nature of rolling friction and the impact of economic factors. By 1800 the essential features of ball and rolling-element bearings had emerged and it only remained for precision manufacture and mass production to confirm the value of these fascinating machine elements.

  4. Hybrid superconductor magnet bearings

    SciTech Connect

    Chu, W.

    1995-04-01

    Hybrid superconductor magnet bearings (HSMB`s) utilize high temperature superconductors (HTS`s) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS`s, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, the authors present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  5. Hybrid superconductor magnet bearings

    NASA Astrophysics Data System (ADS)

    Chu, Wei-Kan

    1995-04-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  6. Magnetic Bearings For Turbopumps

    NASA Technical Reports Server (NTRS)

    Meeks, Crawford R.; Mendez, Antonio J.

    1995-01-01

    Report presents study of feasibility of magnetic bearings in turbopumps. Liquid-oxygen turbopump in space shuttle main engine selected for study. Other potential applications include manned and unmanned spacecraft, gas turbines for commercial and military aircraft, turbomachinery for petro-chemical and gas operations, suspension systems for precise machinery, and precise pointing and tracking systems.

  7. The Teddy Bears' Disc.

    ERIC Educational Resources Information Center

    Laurillard, Diana

    1985-01-01

    Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)

  8. Hybrid superconductor magnet bearings

    NASA Technical Reports Server (NTRS)

    Chu, Wei-Kan

    1995-01-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  9. Composite Bear Canister

    NASA Technical Reports Server (NTRS)

    Chung, W. Richard; Jara, Steve; Suffel, Susan

    2003-01-01

    To many national park campers and mountain climbers saving their foods in a safe and unbreakable storage container without worrying being attacked by a bear is a challenging task. In some parks, the park rangers have mandated that park visitors rent a bear canister for their food storage. Commercially available bear canisters are made of ABS plastic, weigh 2.8 pounds, and have a 180 cubic inch capacity for food storage. A new design with similar capacity was conducted in this study to reduce its weight and make it a stiffer and stronger canister. Two prototypes incorporating carbon prepreg with and without honeycomb constructions were manufactured using hand lay-up and vacuum bag forming techniques. A 6061-T6-aluminum ring was machined to dimensions in order to reinforce the opening area of the canister. Physical properties (weight and volume) along with mechanical properties (flexural strength and specific allowable moment) of the newly fabricated canisters are compared against the commercial ones. The composite canister weighs only 56% of the ABS one can withstand 9 times of the force greater. The advantages and limitations of using composite bear canisters will be discussed in the presentation.

  10. Optimal Synchronizability of Bearings

    NASA Astrophysics Data System (ADS)

    Araújo, N. A. M.; Seybold, H.; Baram, R. M.; Herrmann, H. J.; Andrade, J. S., Jr.

    2013-02-01

    Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with asymmetrically weighted couplings. Accordingly, these networks can exhibit optimal synchronization properties through fine-tuning of the local interaction strength as a function of node degree [Motter, Zhou, and Kurths, Phys. Rev. E 71, 016116 (2005)PLEEE81539-3755]. We show that, in analogy, the synchronizability of bearings can be maximized by counterbalancing the number of contacts and the inertia of their constituting rotor disks through the mass-radius relation, m˜rα, with an optimal exponent α=α× which converges to unity for a large number of rotors. Under this condition, and regardless of the presence of a long-tailed distribution of disk radii composing the mechanical system, the average participation per disk is maximized and the energy dissipation rate is homogeneously distributed among elementary rotors.

  11. Magnetically leviated superconducting bearing

    DOEpatents

    Weinberger, Bernard R.; Lynds, Jr., Lahmer

    1993-01-01

    A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.

  12. Lubricant effects on bearing life

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1986-01-01

    Lubricant considerations for rolling-element bearings have within the last two decades taken on added importance in the design and operation of mechanical systems. The phenomenon which limits the useful life of bearings is rolling-element or surface pitting fatigue. The elastohydrodynamic (EHD) film thickness which separates the ball or roller surface from those of the raceways of the bearing directly affects bearing life. Chemical additives added to the lubricant can also significantly affect bearings life and reliability. The interaction of these physical and chemical effects is important to the design engineer and user of these systems. Design methods and lubricant selection for rolling-element bearings are presented and discussed.

  13. Magnetic-Bearing Test Fixture

    NASA Technical Reports Server (NTRS)

    Groom, Nelson J.; Poole, William L.

    1991-01-01

    Microcomputer-controlled magnetic-bearing test fixture used to develop approaches to design of controls for magnetic bearing actuators designed and constructed. Includes load cells connected to bar, in turn, connected through screw positioners to geared drive motors. Position of equivalent suspended element sensed by position sensors and controlled by drive motors. Provides control of gap in magnetic bearing and of current in electromagnet coil. Measurements made include magnetic-bearing gaps, magnetic flux in bearing gaps, and bearing forces. Approaches to linearization and control developed by use of fixture applicable to wide range of small-gap suspension systems.

  14. Flexure Bearing Reduces Startup Friction

    NASA Technical Reports Server (NTRS)

    Clingman, W. Dean

    1991-01-01

    Design concept for ball bearing incorporates small pieces of shim stock, wire spokes like those in bicycle wheels, or other flexing elements to reduce both stiction and friction slope. In flexure bearing, flexing elements placed between outer race of ball bearing and outer ring. Elements flex when ball bearings encounter small frictional-torque "bumps" or even larger ones when bearing balls encounter buildups of grease on inner or outer race. Flexure of elements reduce high friction slopes of "bumps", helping to keep torque between outer ring and inner race low and more nearly constant. Concept intended for bearings in gimbals on laser and/or antenna mirrors.

  15. Particle migration through sealed bearings

    SciTech Connect

    Sundvold, P.D.

    1993-08-01

    Tests were performed to determine the ability of various types of shielded bearings to isolate particulate from a clean environment in support of the Direct Optical Initiation (DOI) program. In the DOI firing system, a stronglink mechanism will share the same environment with a high-powered laser which needs uncontaminated optics to perform properly. Two commercially available shielded and sealed bearings were tested along with a sealed bearing designed at Allied Signal Inc., Kansas City Division (KCD). The KCD-designed bearing proved to be the best barrier, but the torque required to function the bearing was magnitudes above the commercial bearings. The commercial sealed bearing was an effective barrier, allowing a small fraction of particles to migrate through, and had a relatively low running torque. The shielded bearing was not acceptable as a particle barrier.

  16. Vygotsky and the Three Bears

    ERIC Educational Resources Information Center

    Kulczewski, Peggy

    2004-01-01

    Peggy Kulczewski, a kindergarten classroom teacher, remembers the day when students enjoyed a story she told them from the book "The Three Bears". The students' discussion about comparison of the bears was very helpful to the whole group.

  17. Magnetic bearings grow more attractive

    SciTech Connect

    Not Available

    1993-10-01

    Advances in materials and electronics have enabled designers to devise simpler, smaller magnetic bearings. As a result, costs have dropped, widening the applications for these very-low-friction devices. Avcon (Advanced Controls Technology) has patented a permanent-magnet bias actively controlled bearing. Here high-energy rare earth permanent-magnet materials supply the basic bearing load levitation, while servo-driven electromagnets generate stabilization and centering forces for motion contol. Previous heavy-duty magnetic bearings used electromagnets entirely for suspension and control, which led to large bearings and control systems with higher power requirements. Avcon has developed several types of permanent-magnet bias bearings. The simplest is the radial repulsion bearing. Avcon's homopolar permanent-magnet bias active bearing is the most versatile of the company's designs.

  18. Externally Pressurized Journal Gas Bearings

    NASA Technical Reports Server (NTRS)

    Laub, John H.

    1959-01-01

    Externally pressurized gas-lubricated bearings with multiple orifice feed are investigated. An analytical treatment is developed for a semi-cylindrical bearing with 9 orifices and for a cylindrical journal bearing with 192 radial and 24 axial orifices. Experiments are described on models of the two bearing configurations with specially designed fixtures which incorporate pneumatic loading and means for determining pressure profiles, gas flow and gap height. The correlation between theory and experiment is satisfactory.

  19. Passive magnetic bearing system

    DOEpatents

    Post, Richard F.

    2014-09-02

    An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

  20. Magnetic bearing and motor

    NASA Technical Reports Server (NTRS)

    Studer, Philip A. (Inventor)

    1983-01-01

    A magnetic bearing assembly (10) has an intermediate rotatable section (33) having an outer cylindrical member (30) coaxially suspended by a torsion wire (72) around an axially polarized cylindrical magnet (32). Axial alignment between the pole faces (40-43) of the intermediate section (33) and end surfaces (50-53) of opposed end bells (20, 22) provides a path of least reluctance across intervening air gaps (60-63) for the magnetic flux emanating from magnet (32). Radial dislocation increases the reluctance and creates a radial restoring force. Substitution of radially polarized magnets 107 fixed to a magnetically permeable cylinder (32') and insertion of pairs of armature coil windings (109-112) between the cylinder pair (33') provides an integral magnetic bearing and torsion motor (100) able to provide arcuately limited rotational drive.

  1. Centrifugally decoupling touchdown bearings

    DOEpatents

    Post, Richard F

    2014-06-24

    Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

  2. Rotating plug bearing and seal

    DOEpatents

    Wade, Elman E.

    1977-01-01

    A bearing and seal structure for nuclear reactors utilizing rotating plugs above the nuclear reactor vessel. The structure permits lubrication of bearings and seals of the rotating plugs without risk of the lubricant draining into the reactor vessel below. The structure permits lubrication by utilizing a rotating outer race bearing.

  3. Frictionless Bearing Uses Permanent Magnets

    NASA Technical Reports Server (NTRS)

    1965-01-01

    The purpose of this innovation was to develop a frictionless bearing for high speed, light load applications. The device involves the incorporation of permanent magnets in the bearing design. The repulsion of like magnetic poles provides concentric support of the inner member so that no metallic contact occurs between the bearing surfaces.

  4. Big Bear Solar Observatory

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Big Bear Solar Observatory (BBSO) is located at the end of a causeway in a mountain lake more than 2 km above sea level. The site has more than 300 sunny days a year and a natural inversion caused by the lake which makes for very clean images. BBSO is the only university observatory in the US making high-resolution observations of the Sun. Its daily images are posted at http://www.bbso.njit.e...

  5. Radium bearing waste disposal

    SciTech Connect

    Tope, W.G.; Nixon, D.A.; Smith, M.L.; Stone, T.J.; Vogel, R.A.; Schofield, W.D.

    1995-07-01

    Fernald radium bearing ore residue waste, stored within Silos 1 and 2 (K-65) and Silo 3, will be vitrified for disposal at the Nevada Test Site (NTS). A comprehensive, parametric evaluation of waste form, packaging, and transportation alternatives was completed to identify the most cost-effective approach. The impacts of waste loading, waste form, regulatory requirements, NTS waste acceptance criteria, as-low-as-reasonably-achievable principles, and material handling costs were factored into the recommended approach.

  6. Magnetic translator bearings

    NASA Technical Reports Server (NTRS)

    Hockney, Richard L. (Inventor); Downer, James R. (Inventor); Eisenhaure, David B. (Inventor); Hawkey, Timothy J. (Inventor); Johnson, Bruce G. (Inventor)

    1990-01-01

    A magnetic bearing system for enabling translational motion includes a carriage and a shaft for movably supporting the carriage; a first magnetic bearing fixed to one of the carriage and shaft and slidably received in a first channel of the other of the carriage and shaft. The first channel is generally U shaped with two side walls and a back wall. The magnetic bearing includes a pair of spaced magnetic pole pieces, each pole piece having a pair of electromagnetic coils mounted on poles on opposite ends of the pole piece proximate the side walls, and a third electromagnetic coil mounted on a pole of the pole piece proximate the backwall; a motion sensor for sensing translational motion along two axes and rotationally about three axes of the carriage and shaft relative to each other; and a correction circuit responsive to the sensor for generating a correction signal to drive the coils to compensate for any misalignment sensed between the carriage and the shaft.

  7. The series hybrid bearing - A new high speed bearing concept.

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.; Fleming, D. P.; Parker, R. J.

    1971-01-01

    The series-hybrid bearing couples a fluid-film bearing with a rolling-element bearing such that the rolling-element bearing inner race runs at a fraction of shaft speed. A series-hybrid bearing was analyzed and experiments were run at thrust loads from 100 to 300 lb and speeds from 4000 to 30,000 rpm. Agreement between theoretical and experimental speed sharing was good. The lowest speed ratio (ratio of ball bearing inner-race speed to shaft speed) obtained was 0.67. This corresponds to an approximate reduction in DN value of 1/3. For a ball bearing in a 3 million DN application, fatigue life would theoretically be improved by a factor as great as 8.

  8. Anti-backlash gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2009-01-01

    A gear bearing having a first gear and a second gear, each having a plurality of teeth. Each gear operates on two non-parallel surfaces of the opposing gear teeth to perform both gear and bearing functions simultaneously. The gears are moving at substantially the same speed at their contact points. The gears may be roller gear bearings or phase-shifted gear bearings, and may be arranged in a planet/sun system or used as a transmission. One preferred embodiment discloses and describes an anti-backlash feature to counter ''dead zones'' in the gear bearing movement.

  9. Hybrid Bearing Prognostic Test Rig

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Certo, Joseph M.; Handschuh, Robert F.; Dimofte, Florin

    2005-01-01

    The NASA Glenn Research Center has developed a new Hybrid Bearing Prognostic Test Rig to evaluate the performance of sensors and algorithms in predicting failures of rolling element bearings for aeronautics and space applications. The failure progression of both conventional and hybrid (ceramic rolling elements, metal races) bearings can be tested from fault initiation to total failure. The effects of different lubricants on bearing life can also be evaluated. Test conditions monitored and recorded during the test include load, oil temperature, vibration, and oil debris. New diagnostic research instrumentation will also be evaluated for hybrid bearing damage detection. This paper summarizes the capabilities of this new test rig.

  10. Bearing for liquid metal pump

    DOEpatents

    Dickinson, Robert J.; Wasko, John; Pennell, William E.

    1984-01-01

    A liquid metal pump bearing support comprises a series of tangentially oriented spokes that connect the bearing cylinder to the pump internals structure. The spokes may be arranged in a plurality of planes extending from the bearing cylinder to the pump internals with the spokes in one plane being arranged alternately with those in the next plane. The bearing support structure provides the pump with sufficient lateral support for the bearing structure together with the capability of accommodating differential thermal expansion without adversely affecting pump performance.

  11. Bearing, gearing, and lubrication technology

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.

    1978-01-01

    Results of selected NASA research programs on rolling-element and fluid-film bearings, gears, and elastohydrodynamic lubrication are reported. Advances in rolling-element bearing material technology, which have resulted in a significant improvement in fatigue life, and which make possible new applications for rolling bearings, are discussed. Research on whirl-resistant, fluid-film bearings, suitable for very high-speed applications, is discussed. An improved method for predicting gear pitting life is reported. An improved formula for calculating the thickness of elastohydrodynamic films (the existence of which help to define the operating regime of concentrated contact mechanisms such as bearings, gears, and cams) is described.

  12. Bearing construction for refrigeration compressor

    SciTech Connect

    Middleton, M.G.; Nelson, R.T.

    1988-01-12

    A hermetic refrigeration compressor has a cylinder block and a crankshaft rotatable about a vertical axis to reciprocate a piston in a cylinder on the cylinder block. A separate bearing housing is secured to the central portion of the cylinder block and extends vertically along the crankshaft, where it carries a pair of roller bearings to journal the crankshaft. The crankshaft has a radially extending flange which is journaled by a thrust-type roller bearing above the bearing housing to absorb the vertical forces on the crankshaft so that all three of the roller bearings are between the crankshaft and the bearing housing to maintain and control the close tolerances required by such bearings. 4 figs.

  13. Bearing construction for refrigeration compresssor

    DOEpatents

    Middleton, Marc G.; Nelson, Richard T.

    1988-01-01

    A hermetic refrigeration compressor has a cylinder block and a crankshaft rotatable about a vertical axis to reciprocate a piston in a cylinder on the cylinder block. A separate bearing housing is secured to the central portion of the cylinder block and extends vertically along the crankshaft, where it carries a pair of roller bearings to journal the crankshaft. The crankshaft has a radially extending flange which is journaled by a thrust-type roller bearing above the bearing housing to absorb the vertical forces on the crankshaft so that all three of the roller bearings are between the crankshaft and the bearing housing to maintain and control the close tolerances required by such bearings.

  14. Damping Bearings In High-Speed Turbomachines

    NASA Technical Reports Server (NTRS)

    Von Pragenau, George L.

    1994-01-01

    Paper presents comparison of damping bearings with traditional ball, roller, and hydrostatic bearings in high-speed cryogenic turbopumps. Concept of damping bearings described in "Damping Seals and Bearings for a Turbomachine" (MFS-28345).

  15. Effect of Bearing Cleaning on Long Term Bearing Life

    NASA Technical Reports Server (NTRS)

    Jett, Tim; Thom, R. L.

    1999-01-01

    For many years chlorofluorocarbon (CFC) based solvents, such as CFC-113 and 1,1,1, trichloroethane (TCA), were used as bearing cleaning solvents for space mechanism bearings. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change requiring the use of ODC-free cleaners for precision bearing cleaning. With this change the question arises; what effect if any do these new cleaners have on long term bearing life? The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings per motor) was conducted in a high vacuum environment (2.0 x 10(exp -6) torr) at a temperature of 90 C. Prior to testing the bearings were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing, the mass of each lubricated bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition, the bearings were visually examined and analyzed using an optical microscope.

  16. Introgressive hybridization: brown bears as vectors for polar bear alleles.

    PubMed

    Hailer, Frank

    2015-03-01

    The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. PMID:25775930

  17. Gold-bearing skarns

    USGS Publications Warehouse

    Theodore, Ted G.; Orris, Greta J.; Hammerstrom, Jane M.; Bliss, James D.

    1991-01-01

    In recent years, a significant proportion of the mining industry's interest has been centered on discovery of gold deposits; this includes discovery of additional deposits where gold occurs in skarn, such as at Fortitude, Nevada, and at Red Dome, Australia. Under the classification of Au-bearing skarns, we have modeled these and similar gold-rich deposits that have a gold grade of at least 1 g/t and exhibit distinctive skarn mineralogy. Two subtypes, Au-skarns and byproduct Au-skarns, can be recognized on the basis of gold, silver, and base-metal grades, although many other geological factors apparently are still undistinguishable largely because of a lack of detailed studies of the Au-skarns. Median grades and tonnage for 40 Au-skarn deposits are 8.6 g/t Au, 5.0 g/t Ag, and 213,000 t. Median grades and tonnage for 50 byproduct and Au-skarn deposits are 3.7 g/t Au, 37 g/t Ag, and 330,000 t. Gold-bearing skarns are generally calcic exoskarns associated with intense retrograde hydrosilicate alteration. These skarns may contain economic amounts of numerous other commodities (Cu, Fe, Pb, Zn, As, Bi, W, Sb, Co, Cd, and S) as well as gold and silver. Most Au-bearing skarns are found in Paleozoic and Cenozoic orogenic-belt and island-arc settings and are associated with felsic to intermediate intrusive rocks of Paleozoic to Tertiary age. Native gold, electru, pyrite, pyrrhotite, chalcopyrite, arsenopyrite, sphalerite, galena, bismuth minerals, and magnetite or hematite are the most common opaque minerals. Gangue minerals typically include garnet (andradite-grossular), pyroxene (diopside-hedenbergite), wollastonite, chlorite, epidote, quartz, actinolite-tremolite, and (or) calcite.

  18. Linear magnetic bearings

    NASA Technical Reports Server (NTRS)

    Goldowskiy, M. P.

    1984-01-01

    A self regulating, nonfrictional, active magnetic bearing is disclosed which has an elongated cylindrical housing for containing a shaft type armature with quadrature positioned shaft position sensors and equidistantly positioned electromagnets located at one end of the housing. Each set of sensors is responsive to orthogonal displacement of the armature and is used to generate control signals to energize the electromagnets to center the armature. A bumper magnet assembly is located at one end of the housing for dampening any undesired axial movement of the armature or to axially move the armature either continuously or fixedly.

  19. Aerospace applications of magnetic bearings

    NASA Technical Reports Server (NTRS)

    Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard

    1994-01-01

    Magnetic bearings have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic bearings have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic bearings in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic bearings programs at SatCon Technology Corporation. The magnetic bearing programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic bearings for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic bearing system for an airborne telescope, and magnetic bearings for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic bearing technologies to the point where magnetic bearings can be truly useful, reliable, and well tested components for the aerospace community.

  20. Effect of Bearing Cleaning on Long Term Bearing Life

    NASA Technical Reports Server (NTRS)

    Jett, Timothy Raymond; Thom, Robert L.

    1998-01-01

    For many years chlorofluorocarbon (CFC ) based solvents, such as Freon and 1,1,1, Trichloroethane (TCA), were used as bearing cleaning solvents for space mechanisms. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change to new ODC-free cleaners for the precision bearing cleaning. With this change the question arises what effect if any do these new cleaners have on long term bearing life. The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings per motor) was conducted in a high vacuum environment (2.0* 10(exp -6) torr) at a temperature of 90C. Prior to testing the bearings were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing the mass of each lubricated bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition the bearings were visually examined and analyzed using an optical microscope.

  1. Reduction in bearing size due to superconductors in magnetic bearings

    NASA Technical Reports Server (NTRS)

    Rao, Dantam K.; Lewis, Paul; Dill, James F.

    1991-01-01

    A design concept that reduces the size of magnetic bearings is assessed. The small size will enable magnetic bearings to fit into limited available bearing volume of cryogenic machinery. The design concept, called SUPERC, uses (high Tc) superconductors or high-purity aluminum conductors in windings instead of copper. The relatively high-current density of these conductors reduces the slot radial thickness for windings, which reduces the size of the bearings. MTI developed a sizing program called SUPERC that translates the high-current density of these conductors into smaller sized bearings. This program was used to size a superconducting bearing to carry a 500 lb. load. The sizes of magnetic bearings needed by various design concepts are as follows: SUPERC design concept = 3.75 in.; magnet-bias design concept = 5.25 in.; and all electromagnet design concept = 7.0 in. These results indicate that the SUPERC design concept can significantly reduce the size of the bearing. This reduction, in turn, reduces the weight and yields a lighter bearing. Since the superconductors have inherently near-zero resistance, they are also expected to save power needed for operation considerably.

  2. Series-hybrid bearing - An approach to extending bearing fatigue life at high speeds

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.; Coe, H. H.; Fleming, D. P.; Parker, R. J.

    1971-01-01

    Fluid film bearing of hybrid device consists of orifice compensated annular thrust bearing and self-acting journal bearing. In series hybrid bearing, both ball bearing and annular thrust bearing carry full system thrust load, but two bearings share speed. Operation of system is stable and automatically fail-safe.

  3. Spin bearing retainer design optimization

    NASA Technical Reports Server (NTRS)

    Boesiger, Edward A.; Warner, Mark H.

    1991-01-01

    The dynamics behavior of spin bearings for momentum wheels (control-moment gyroscope, reaction wheel assembly) is critical to satellite stability and life. Repeated bearing retainer instabilities hasten lubricant deterioration and can lead to premature bearing failure and/or unacceptable vibration. These instabilities are typically distinguished by increases in torque, temperature, audible noise, and vibration induced by increases into the bearing cartridge. Ball retainer design can be optimized to minimize these occurrences. A retainer was designed using a previously successful smaller retainer as an example. Analytical methods were then employed to predict its behavior and optimize its configuration.

  4. Superconducting levitating bearing

    NASA Technical Reports Server (NTRS)

    Moon, Francis C. (Inventor)

    1996-01-01

    A superconducting bearing assembly includes a coil field source that may be superconducting and a superconducting structure. The coil field source assembly and superconducting structure are positioned so as to enable relative rotary movement therebetween. The structure and coil field source are brought to a supercooled temperature before a power supply induces a current in the coil field source. A Meissner-like effect is thereby obtained and little or no penetration of the field lines is seen in the superconducting structure. Also, the field that can be obtained from the superconducting coil is 2-8 times higher than that of permanent magnets. Since the magnetic pressure is proportioned to the square of the field, magnetic pressures from 4 to 64 times higher are achieved.

  5. The polar bear phenomena

    SciTech Connect

    Maw, P.K. ); Lane, M.T.

    1990-02-01

    Results from measuring the thermal profile of polar bear pelts, reflectiveness of the pelts, and total thermal conversion data lead to the conclusion that the pelts from an ultra-efficient thermal diode for solar-thermal conversion. The transfer of the thermal energy from the surface of the fur to the skin where it is absorbed cannot be thermal, and therefore must be radiative. This process must have an efficiency of better than 90:0090 percent to account for measured values. The radiative transfer process is not known at present. To understand it, a detailed knowledge of the microscopic parameters of the pelts must be obtained. This is the current thrust of the polar solar research. If the process can be understood and synthesized,it will provide a major breakthrough in the area of solar-thermal energy conversion.

  6. Introduction to magnetic bearings

    NASA Astrophysics Data System (ADS)

    Skowronski, Lori; Bisese, Anne

    1993-04-01

    Multi-axis suspension has several advantages over single axis system, in that it provides control of an object with precision in two or three orthogonal axes. In this report, we discuss the primary use of magnetic-bearing suspension and it's relevance to what was formally known as NASA's Annular Suspension and Pointing System (ASPS). This system is an experimental pointing system with applications for the space shuttle and the space station programs. The objectives behind this magnetic suspension research project are to provide insight to the use of the ASPS configuration, to control the solar panels of the space station. This is important to maintain the correct position of the panels in relation to the sun and orbiting space station for the continuous supply of solar energy. Since the panels are suspended, they can be aligned with minimum outside interference. The approach of using magnetic suspension technology guarantees mechanical isolation since there are no contacting surfaces. This isolation reduces vibration transmission and mechanical wear which in turn extends the life of the payload and of the carrier. It should be noted that ASPS has a high pointing accuracy along the line of 0.01 arc-second. This research will be done in a laboratory setting by incorporating five bearing stations and one motion control station. We will attempt to suspend an object of dead weight similar to that of a solar panel. The long term applications may include deep-space navigation, fire control in weapon systems, and an improved mass transit system.

  7. Introduction to magnetic bearings

    NASA Technical Reports Server (NTRS)

    Skowronski, Lori; Bisese, Anne

    1993-01-01

    Multi-axis suspension has several advantages over single axis system, in that it provides control of an object with precision in two or three orthogonal axes. In this report, we discuss the primary use of magnetic-bearing suspension and it's relevance to what was formally known as NASA's Annular Suspension and Pointing System (ASPS). This system is an experimental pointing system with applications for the space shuttle and the space station programs. The objectives behind this magnetic suspension research project are to provide insight to the use of the ASPS configuration, to control the solar panels of the space station. This is important to maintain the correct position of the panels in relation to the sun and orbiting space station for the continuous supply of solar energy. Since the panels are suspended, they can be aligned with minimum outside interference. The approach of using magnetic suspension technology guarantees mechanical isolation since there are no contacting surfaces. This isolation reduces vibration transmission and mechanical wear which in turn extends the life of the payload and of the carrier. It should be noted that ASPS has a high pointing accuracy along the line of 0.01 arc-second. This research will be done in a laboratory setting by incorporating five bearing stations and one motion control station. We will attempt to suspend an object of dead weight similar to that of a solar panel. The long term applications may include deep-space navigation, fire control in weapon systems, and an improved mass transit system.

  8. Service Lives Of Restored Bearings

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1988-01-01

    Rebuilt units last almost as long as new ones. Report describes theoretical and experiemental studies of lifetimes of restored ball and cylindrical-roller bearings. Results of this and related studies have implications of economy and safety in modern high-speed machinery, especially in aircraft industry, where inspection and rejection or replacing of bearings are new standard practice.

  9. Lubrication of rolling element bearings

    NASA Technical Reports Server (NTRS)

    Parker, R. J.

    1980-01-01

    This paper is a broad survey of the lubrication of rolling-element bearings. Emphasis is on the critical design aspects related to speed, temperature, and ambient pressure environment. Types of lubrication including grease, jets, mist, wick, and through-the-race are discussed. The paper covers the historical development, present state of technology, and the future problems of rolling-element bearing lubrication.

  10. Permanent-Magnet Meissner Bearing

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A.

    1994-01-01

    Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

  11. Nonlinear control of magnetic bearings

    NASA Technical Reports Server (NTRS)

    Pradeep, A. K.; Gurumoorthy, R.

    1994-01-01

    In this paper we present a variety of nonlinear controllers for the magnetic bearing that ensure both stability and robustness. We utilize techniques of discontinuous control to design novel control laws for the magnetic bearing. We present in particular sliding mode controllers, time optimal controllers, winding algorithm based controllers, nested switching controllers, fractional controllers, and synchronous switching controllers for the magnetic bearing. We show existence of solutions to systems governed by discontinuous control laws, and prove stability and robustness of the chosen control laws in a rigorous setting. We design sliding mode observers for the magnetic bearing and prove the convergence of the state estimates to their true values. We present simulation results of the performance of the magnetic bearing subject to the aforementioned control laws, and conclude with comments on design.

  12. Space Station alpha joint bearing

    NASA Technical Reports Server (NTRS)

    Everman, Michael R.; Jones, P. Alan; Spencer, Porter A.

    1987-01-01

    Perhaps the most critical structural system aboard the Space Station is the Solar Alpha Rotary Joint which helps align the power generation system with the sun. The joint must provide structural support and controlled rotation to the outboard transverse booms as well as power and data transfer across the joint. The Solar Alpha Rotary Joint is composed of two transition sections and an integral, large diameter bearing. Alpha joint bearing design presents a particularly interesting problem because of its large size and need for high reliability, stiffness, and on orbit maintability. The discrete roller bearing developed is a novel refinement to cam follower technology. It offers thermal compensation and ease of on-orbit maintenance that are not found in conventional rolling element bearings. How the bearing design evolved is summarized. Driving requirements are reviewed, alternative concepts assessed, and the selected design is described.

  13. Geophagy by yellowstone grizzly bears

    USGS Publications Warehouse

    Mattson, D.J.; Green, G.I.; Swalley, R.

    1999-01-01

    We documented 12 sites in the Yellowstone ecosystem where grizzly bears (Ursus arctos horribilis) had purposefully consumed soil (an activity known as geophagy). We also documented soil in numerous grizzly bear feces. Geophagy primarily occurred at sites barren of vegetation where surficial geology had been modified by geothermal activity. There was no evidence of ungulate use at most sites. Purposeful consumption of soil by bears peaked first from March to May and again from August to October, synchronous with peaks in consumption of ungulate meat and mushrooms. Geophageous soils were distinguished from ungulate mineral licks and soils in general by exceptionally high concentrations of potassium (K) and high concentrations of magnesium (Mg) and sulphur (S). Our results do not support the hypotheses that bears were consuming soil to detoxify secondary compounds in grazed foliage, as postulated for primates, or to supplement dietary sodium, as known for ungulates. Our results suggest that grizzly bears could have been consuming soil as an anti-diarrheal.

  14. Effects of bearing cleaning and lube environment on bearing performance

    NASA Technical Reports Server (NTRS)

    Ward, Peter C.

    1995-01-01

    Running torque data of SR6 ball bearings are presented for different temperatures and speeds. The data are discussed in contrast to generally used torque prediction models and point out the need to obtain empirical data in critical applications. Also, the effects of changing bearing washing techniques from old, universally used CFC-based systems to CFC-free aqueous/alkaline solutions are discussed. Data on wettability, torque and lubricant life using SR3 ball bearings are presented. In general, performance is improved using the new aqueous washing techniques.

  15. Magnetic Bearings at Draper Laboratory

    NASA Technical Reports Server (NTRS)

    Kondoleon, Anthony S.; Kelleher, William P.; Possel, Peter D.

    1996-01-01

    Magnetic bearings, unlike traditional mechanical bearings, consist of a series of components mated together to form a stabilized system. The correct design of the actuator and sensor will provide a cost effective device with low power requirements. The proper choice of a control system utilizes the variables necessary to control the system in an efficient manner. The specific application will determine the optimum design of the magnetic bearing system including the touch down bearing. Draper for the past 30 years has been a leader in all these fields. This paper summarizes the results carried out at Draper in the field of magnetic bearing development. A 3-D radial magnetic bearing is detailed in this paper. Data obtained from recently completed projects using this design are included. One project was a high radial load (1000 pound) application. The second was a high speed (35,000 rpm), low loss flywheel application. The development of a low loss axial magnetic bearing is also included in this paper.

  16. SSME turbopump bearing analytical study

    NASA Technical Reports Server (NTRS)

    Kannel, J. W.; Merriman, T.

    1980-01-01

    Three shuttle pump bearings operating under severe overspeed and shut-down conditions are evaluated. The specific parameters investigated include outer race stresses, cage stresses, cage-race drag, bearing heating, and crush loading. A quasi-dynamic version of the BASDAP computer code was utilized which involved the calculation of ball-race forces (inner and outer), contact pressures, contact dimensions, and contact angles as a function of (1) axial load, (2) radial load, and (3) centrifugal load on the bearing. Generally, radial loads on the order of 13,300 N (3000 pounds) per bearing or 26,700 N (6000 pounds) per bearing pair, could be expected to cause severe problems to any of the bearings with a 17,800 N (4000 pounds) axial load. Further, when possible temperature excursions are considered, even a load of 8900 N (2000 pounds) may be excessive. However, high momentary radial loads with a 3800 N (850 pounds) axial load would not be anticipated to cause catastrophic failure of the fuel pump bearing.

  17. Hybrid Hydrostatic/Transient Roller Bearing Assembly

    NASA Technical Reports Server (NTRS)

    Justak, John F.

    1992-01-01

    Proposed bearing assembly for shaft of high-speed turbopump includes both hydrostatic and rolling-element bearings. Rolling-element bearing unloaded at high speed by centrifugal expansion of outer race and transient retainer.

  18. Two pad axially grooved hydrostatic bearing

    NASA Technical Reports Server (NTRS)

    San Andres, Luis A. (Inventor)

    1995-01-01

    A hydrostatic bearing having two axial grooves on opposite sides of the bearing for breaking the rotational symmetry in the dynamic force coefficients thus reducing the whirl frequency ratio and increasing the damping and stiffness of the hydrostatic bearing.

  19. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  20. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  1. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  2. Fluid Film Bearing Code Development

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The next generation of rocket engine turbopumps is being developed by industry through Government-directed contracts. These turbopumps will use fluid film bearings because they eliminate the life and shaft-speed limitations of rolling-element bearings, increase turbopump design flexibility, and reduce the need for turbopump overhauls and maintenance. The design of the fluid film bearings for these turbopumps, however, requires sophisticated analysis tools to model the complex physical behavior characteristic of fluid film bearings operating at high speeds with low viscosity fluids. State-of-the-art analysis and design tools are being developed at the Texas A&M University under a grant guided by the NASA Lewis Research Center. The latest version of the code, HYDROFLEXT, is a thermohydrodynamic bulk flow analysis with fluid compressibility, full inertia, and fully developed turbulence models. It can predict the static and dynamic force response of rigid and flexible pad hydrodynamic bearings and of rigid and tilting pad hydrostatic bearings. The Texas A&M code is a comprehensive analysis tool, incorporating key fluid phenomenon pertinent to bearings that operate at high speeds with low-viscosity fluids typical of those used in rocket engine turbopumps. Specifically, the energy equation was implemented into the code to enable fluid properties to vary with temperature and pressure. This is particularly important for cryogenic fluids because their properties are sensitive to temperature as well as pressure. As shown in the figure, predicted bearing mass flow rates vary significantly depending on the fluid model used. Because cryogens are semicompressible fluids and the bearing dynamic characteristics are highly sensitive to fluid compressibility, fluid compressibility effects are also modeled. The code contains fluid properties for liquid hydrogen, liquid oxygen, and liquid nitrogen as well as for water and air. Other fluids can be handled by the code provided that the

  3. Random bearings and their stability.

    PubMed

    Mahmoodi Baram, Reza; Herrmann, Hans J

    2005-11-25

    Self-similar space-filling bearings have been proposed some time ago as models for the motion of tectonic plates and appearance of seismic gaps. These models have two features which, however, seem unrealistic, namely, high symmetry in the arrangement of the particles, and lack of a lower cutoff in the size of the particles. In this work, an algorithm for generating random bearings in both two and three dimensions is presented. Introducing a lower cutoff for the sizes of the particles, the instabilities of the bearing under an external force such as gravity, are studied. PMID:16384225

  4. Bears, Big and Little. Young Discovery Library Series.

    ERIC Educational Resources Information Center

    Pfeffer, Pierre

    This book is written for children 5 through 10. Part of a series designed to develop their curiosity, fascinate them and educate them, this volume describes: (1) the eight species of bears, including black bear, brown bear, grizzly bear, spectacled bear, sun bear, sloth bear, polar bear, and giant panda; (2) geographical habitats of bears; (3)…

  5. Sputter etching of hemispherical bearings

    NASA Technical Reports Server (NTRS)

    Schiesser, R. J.

    1972-01-01

    Technique was developed for fabricating three dimensional pumping grooves on gas bearings by sputter etching. Method eliminates problems such as groove nonuniformity, profile, and finish, which are associated with normal grooving methods.

  6. Mixed-mu superconducting bearings

    DOEpatents

    Hull, J.R.; Mulcahy, T.M.

    1998-03-03

    A mixed-mu superconducting bearing is disclosed including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure. 9 figs.

  7. Mixed-mu superconducting bearings

    DOEpatents

    Hull, John R.; Mulcahy, Thomas M.

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

  8. A Passive Magnetic Bearing Flywheel

    NASA Technical Reports Server (NTRS)

    Siebert, Mark; Ebihara, Ben; Jansen, Ralph; Fusaro, Robert L.; Morales, Wilfredo; Kascak, Albert; Kenny, Andrew

    2002-01-01

    A 100 percent passive magnetic bearing flywheel rig employing no active control components was designed, constructed, and tested. The suspension clothe rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm, which is 65 percent above the first critical speed of 3336 rpm. Operation was not continued beyond this point because of the excessive noise generated by the air impeller and because of inadequate containment in case of failure. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  9. ATM CMG bearing failure analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The cause or causes for the failure of ATM CMG S/N 5 (Skylab 1) and the anomalies associated with ATM CMG S/N 6 (Skylab 2) were investigated. Skylab telemetry data were reviewed and presented in the form of parameter distributions. The theory that the problems were caused by marginal bearing lubrication was studied along with the effects of orbital conditions on lubricants. Bearing tests were performed to investigate the effect of lubricant or lack of lubricant in the ATM CMG bearings and the dispersion and migration of the lubricant. The vacuum and weightless conditions of space were simulated in the bearing tests. Analysis of the results of the tests conducted points to inadequate lubrication as the predominant factor causing the failure of ATM CMG S/N 5 (Skylab 1) and the anomalies associated with ATM CMG S/N 6 (Skylab 2).

  10. High-temperature bearing lubricants

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.; Parker, R. J.; Zaretsky, E. V.

    1968-01-01

    Synthetic paraffinic oil lubricates ball bearings at temperatures in the 600 degrees F range. The lubricant contains antiwear and antifoam additives, is thermally stable in the high temperature range, but requires protection from oxygen.

  11. Flex bearing UUEC, volume 2

    NASA Technical Reports Server (NTRS)

    Clapper, M. L.

    1993-01-01

    This volume, Volume 2, of this Flex Bearing UUEC Final Report documents findings and data pertaining to Team B's tasks. Team B was organized as one of two sub-teams of the Unplanned/Unintended Event or Condition (UUEC) board established per InterOffice Memorandum (IOM) A100-FY93-072. Team A determined the cause of the unacceptable unbonds (referred to as 'heat-affect' unbonds), including the initial, light rust film, in the FSM #3 flex bearing was overheating of the Forward End Ring (FER) during cure, specifically in zone 8 of the mold. Team A's findings are documented in Volume 1 of this report. Team B developed flight rationale for existing bearings, based on absence or presence of an unpropitious unbond condition like that in FSM #3's flex bearing.

  12. Myrmecophagy by Yellowstone grizzly bears

    USGS Publications Warehouse

    Mattson, D.J.

    2001-01-01

    I used data collected during a study of radio-marked grizzly bears (Ursus arctos horribilis) in the Yellowstone region from 1977 to 1992 to investigate myrmecophagy by this population. Although generally not an important source of energy for the bears (averaging 8 mm long) nested in logs over small ants (6 mm long) nested under stones. Optimal conditions for consumption of ants occurred on the warmest sites with ample substrate suitable for ant nests. For ants in mounds, this occurred at low elevations at non-forested sites. For ants in logs, this occurred at low elevations or on southerly aspects where there was abundant, large-diameter, well-decomposed woody debris under an open forest canopy. Grizzly bears selected moderately decomposed logs 4a??5 dm in diameter at midpoint. Ants will likely become a more important food for Yellowstone's grizzly bears as currently important foods decline, owing to disease and warming of the regional climate.

  13. Lateral dampers for thrust bearings

    NASA Technical Reports Server (NTRS)

    Hibner, D. H.; Szafir, D. R.

    1985-01-01

    The development of lateral damping schemes for thrust bearings was examined, ranking their applicability to various engine classes, selecting the best concept for each engine class and performing an in-depth evaluation. Five major engine classes were considered: large transport, military, small general aviation, turboshaft, and non-manrated. Damper concepts developed for evaluation were: curved beam, constrained and unconstrained elastomer, hybrid boost bearing, hydraulic thrust piston, conical squeeze film, and rolling element thrust face.

  14. Polyurethane retainers for ball bearings

    NASA Technical Reports Server (NTRS)

    Christy, R. I.

    1973-01-01

    Evaluation of a new ball bearing retainer material is reported. A special composite polyurethane foam ball retainer has been developed that has virtually zero wear, is chemically inert to hydrocarbon lubricants, and stores up to 60 times as much lubricant per unit volume as the most commonly used retainer material, cotton phenolic. This new retainer concept shows promise of years of ball bearing operation without reoiling, based on life testing in high vacuum.

  15. SSME Long-life Bearings

    NASA Technical Reports Server (NTRS)

    Butner, M. F.; Murphy, B. T.

    1986-01-01

    Hybrid hydrostatic/ball bearings for LH2 and LO2 service in turbopumps were studied as a means of improving speed and life capabilities. Four hybrid bearing configurations were designed with emphasis on achieving maximum stiffness and damping. Parallel load bearings were tested at steady-state and transient conditions with LH2 (externally fed) and LN2 (internally fed). The hydrostatic elements were tested with Freon 113 for empirical determination of dynamic characteristics. Tests using an eccentric journal for loading showed the externally and internally fed hydrostatic bearings to have significant separated coefficients of direct stiffness and damping. For the internally fed bearing, the strongly speed-dependent cross-coupling stiffness arising from fluid swirl, along with significant cross-coupling damping, resulted in low net effective stiffness and damping. The test method used can produce separated coefficients with a sufficiently elliptic journal orbit; otherwise, only net effective coefficients combining direct and cross-coupling terms can be determined. Testing with nonsynchronous excitation is recommended to avoid this restriction. Investigation of hard materials, including ceramics, is recommended as a means of eliminating the need for the rolling bearing for startup and shutdown support. The testing was performed in 1984 (LH2), 1985 (LN2) and 1985-86 (Freon).

  16. Designing Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Moore, James D., Jr.

    2007-01-01

    Bearing Analysis Tool (BAT) is a computer program for designing rolling-element bearings for cryogenic turbomachines. BAT provides a graphical user interface (GUI) that guides the entry of data to develop mathematical models of bearings. The GUI breaks model data into logical subsets that are entered through logic-driven input screens. The software generates a threedimensional graphical model of a bearing as the data are entered. Most dataentry errors become immediately obvious in the graphical model. BAT provides for storage of all the data on a shaft/bearing system, enabling the creation of a library of proven designs. Data from the library can be transferred to subsequent projects by use of simple cut-and-paste routines. BAT includes a library of temperature- dependent cryogenic bearing-material properties for use in the mathematical models. BAT implements algorithms that (1) enable the user to select combinations of design and/or operating-condition parameters, and then (2) automatically optimize the design by performing trade studies over all of the parameter combinations. This feature enables optimization over a large trade space in a fraction of the time taken when using prior bearingmodel software.

  17. Gimbal bearing design considerations and friction control

    NASA Technical Reports Server (NTRS)

    Kramer, N. R.

    1979-01-01

    The design considerations of bearing selection, bearing fits, bearing installation, and thermal control are discussed for a gimbal with a high stiffness, low friction torque requirement. Tradeoffs between a quad set of small diameter spread apart or a large diameter bearing pair resulted in a cleaner, lighter, stiffer unit with the latter selection. Bearing fits were designed to eliminate clearances with tolerances of .00127 mm 00005 in) on the bearing shafts and housings. The problems in metrology are discussed and a perferred technique for measurement of small cross-section bearings described. A technique for installation to assure proper seating of the bearing is offered. Where transient thermal conditions are involved, a method of controlling bearing friction by active control of bearing temperature gradients including the use of bearing unload test curves is described.

  18. Testing and Lubrication for Single Race Bearings

    SciTech Connect

    Steinhoff, R.G.

    1998-03-04

    Three ES and H-compatible lubricants (Environment, Safety and Health) for single race bearing applications and one hybrid-material single race bearings were evaluated and compared against single race bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in stronglink mechanisms since 1974. Hybrid bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, bearings lubricated with titanium carbide (TiC) on the balls, bearings lubricated with sputtered MoS{sub 2} on races and retainers, and bearings lubricated with electrophoretically deposited MoS{sub 2} were evaluated. The bearings were maintained in a preloaded state in bearing cartridges during cycling and vibration tests. Bearings with electrophoretically deposited MoS{sub 2} performed as well as bearings lubricated with Vydax and were the best performing candidate. All candidates were suitable for low preload applications. Bearings with TiC coated balls and bearings lubricated with sputtered MoS{sub 2} on the races and retainers performed well at high preloads, though not as well as bearings lubricated with electrophoretic deposition of MoS{sub 2}. Bearings with silicon nitride balls were not suitable for high preload applications.

  19. 77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-26

    ... Energy Regulatory Commission Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of Application for Partial Transfer of Licenses, and Soliciting Comments and Motions To Intervene On October 25, 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor)...

  20. Results of differential elevon/aileron deflection for lateral control optimization and elevon hinge moment investigations on an 0.015-scale model (49-0) of the space shuttle orbiter in the NASA/Langley Research Center 8 foot TPT (OA116)

    NASA Technical Reports Server (NTRS)

    Lindsey, A. I.; Milam, M. D.

    1974-01-01

    Aerodynamic investigations were conducted in a transonic pressure tunnel on an 0.015 scale model of the space shuttle orbiter. Major test objectives were to determine: (1) transonic differential elevon/aileron lateral control optimization; (2) transonic elevon hinge moments; (3) transonic effects of the baseline 6 inch elevon/elevon and elevon/fuselage gaps; and (4) transonic effects of the short OMS pods. Six-component aerodynamic force and moment, and elevon hinge moment data, were recorded over an angle-of-attack range form -2 to +22 degrees.

  1. Bear reintroduction: Lessons and challenges

    USGS Publications Warehouse

    Clark, Joseph D.; Huber, Djuro; Servheen, Christopher

    2002-01-01

    Reintroduction is defined as an attempt to establish a species in an area that was once part of its historical range, but from which it has been extirpated or become extinct. Historically, one of the most successful programs was the reintroduction of 254 American black bears (Ursus americanus) from Minnesota to the Interior Highlands of Arkansas in the 1960s; that population has grown to >2,500 today. More recent efforts have involved fewer but better monitored animals and have sometimes employed techniques to improve site fidelity and survival. In Pennsylvania, for example, pregnant female American black bears were successfully translocated from winter dens, the premise being that the adult females would be less likely to return because of the presence of young cubs. That winter-release technique was compared to summer trapping and release in Tennessee; winter releases resulted in greater survival and reduced post-release movements. Homing has not been a problem for small numbers of brown bears (Ursus arctos) reintroduced to the Cabinet-Yaak ecosystem in Montana and Idaho and to the mountains of Austria and France. Reintroduction success appears to be correlated with translocation distance and is greater for subadults and females. As with any small population, reintroduced bear populations are susceptible to environmental variation and stochastic demographic and genetic processes. Although managers have focused on these biological barriers, sociopolitical impediments to bear reintroduction are more difficult to overcome. Poor public acceptance and understanding of bears are the main reasons some reintroduction programs have been derailed. Consequently, the public should be involved in the reintroduction process from the outset; overcoming negative public perceptions about bear reintroduction will be our greatest challenge.

  2. Hydrostatic liquid-bearing for precision gyro

    NASA Technical Reports Server (NTRS)

    Sgambati, R. J.

    1971-01-01

    Unit with 2W power increase and slightly larger overall dimensions performs as well as or better than its gas-bearing counterpart. Liquid-bearings are built by reworking serviceable gas-bearing components /sleeves, endplates, and cylinders/. Hydrostatic bearing is self-centered, requiring no magnetic suspension or centering jewel.

  3. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  4. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  5. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  6. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  7. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  8. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  9. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  10. Investigations of a bearing fault detector for railroad bearings

    NASA Technical Reports Server (NTRS)

    Wilson, D. S.; Frarey, J. L.

    1975-01-01

    The laboratory tests are described which were conducted on new and damaged bearings to determine the feasibility of using high-frequency vibration as a diagnostic tool. A high-frequency band pass filter and demodulator was assembled to permit field measurements of the high-frequency vibrations. Field tests were conducted on an actual truck and on an axle assembly run in a grease test rig. These field tests were directed toward demonstration of the suitability and capabilities of the high-frequency technique for field application. Two specific areas of field application were identified as being cost effective for railroad use. One area is the examination of railroad roller bearings at a derailment site, and the second is as a wayside detector to supplement present hot box detectors for defective roller bearings.

  11. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, J.R.

    1982-05-04

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion. 3 figs.

  12. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, James R.

    1982-01-01

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  13. Cryogenic Magnetic Bearing Test Facility (CMBTF)

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Cryogenic Magnetic Bearing Test Facility (CMBTF) was designed and built to evaluate compact, lightweight magnetic bearings for use in the SSME's (space shuttle main engine) liquid oxygen and liquid hydrogen turbopumps. State of the art and tradeoff studies were conducted which indicated that a hybrid permanent magnet bias homopolar magnetic bearing design would be smaller, lighter, and much more efficient than conventional industrial bearings. A test bearing of this type was designed for the test rig for use at both room temperature and cryogenic temperature (-320 F). The bearing was fabricated from state-of-the-art materials and incorporated into the CMBTF. Testing at room temperature was accomplished at Avcon's facility. These preliminary tests indicated that this magnetic bearing is a feasible alternative to older bearing technologies. Analyses showed that the hybrid magnetic bearing is one-third the weight, considerably smaller, and uses less power than previous generations of magnetic bearings.

  14. Application of foil bearings to helium turbocompressor

    SciTech Connect

    Chen, H.Ming; Howarth, R.; Bernard, Geren; Theilacker, Jay C.; Soyars, William M.; /Fermilab

    2001-01-01

    Hydrodynamic gas-lubricated foil bearings are ideal for machinery that operates at high speed or in extreme-temperature environments. As motors and generators run at higher speeds with more torque capacity, the need for commonly available, robust, high-speed, low-loss foil bearings is clear. This paper presents an application example of the successful replacement of a tape-type bearing for a bump-type bearing in a helium turbocompressor. Both bearing types are described, as are the steps involved in design and fabrication of the bump bearing, and results of comparison tests between the original and replacement bearings. Methods to analyze bump-type foil bearings with commercially available software are reviewed to further emphasize the inherent simplicity of these bearings. By providing the engineering community with the understanding needed to successfully apply foil bearings, the authors hope that the benefits and true potential of this technology will finally be realized.

  15. Superconductor bearings, flywheels and transportation

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Floegel-Delor, U.; Rothfeld, R.; Riedel, T.; Goebel, B.; Wippich, D.; Schirrmeister, P.

    2012-01-01

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  16. [Controlled weight bearing after osteosynthesis].

    PubMed

    Perren, T; Matter, P

    1993-01-01

    Patient compliance with postoperative partial weight bearing can be a difficult management problem. The problem may be intentional or unintentional. There is no objective way to assess the amount of weight placed on the lower extremity by the patient. It is our clinical suspicion that patients place more weight than is desirable on the effected limb. There are few reports in the literature on this topic. One study has confirmed our suspicion of poor patient compliance with postoperative weight bearing. Our goal is to develop a system to accurately assess weight bearing and to improve this aspect of postoperative fracture care. Through an active feedback device we hope to improve patient education and understanding. We plan to study the clinical applications of using a pressure sensitive shoe insert device. Our ultimate goal is to improve upon the present device and to study the clinical application of there use. PMID:8123330

  17. 'Dodo' and 'Baby Bear' Trenches

    NASA Technical Reports Server (NTRS)

    2008-01-01

    NASA's Phoenix Mars Lander's Surface Stereo Imager took this image on Sol 11 (June 5, 2008), the eleventh day after landing. It shows the trenches dug by Phoenix's Robotic Arm. The trench on the left is informally called 'Dodo' and was dug as a test. The trench on the right is informally called 'Baby Bear.' The sample dug from Baby Bear will be delivered to the Phoenix's Thermal and Evolved-Gas Analyzer, or TEGA. The Baby Bear trench is 9 centimeters (3.1 inches) wide and 4 centimeters (1.6 inches) deep.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  18. Air bearing vacuum seal assembly

    DOEpatents

    Booth, Rex

    1978-01-01

    An air bearing vacuum seal assembly capable of rotating at the speed of several thousand revolutions per minute using an air cushion to prevent the rotating and stationary parts from touching, and a two stage differential pumping arrangement to maintain the pressure gradient between the air cushion and the vacuum so that the leak rate into the vacuum is, for example, less than 1 .times. 10.sup.-4 Pa m.sup.3 /s. The air bearing vacuum seal has particular application for mounting rotating targets to an evacuated accelerator beam tube for bombardment of the targets with high-power charged particle beams in vacuum.

  19. Vibrations of Hybrid Ceramic Ball Bearings

    NASA Astrophysics Data System (ADS)

    Ohta, H.; Kobayashi, K.

    1996-05-01

    Hybrid ceramic ball bearings with silicone nitride balls and steel rings were tested, and the vibration characteristics were compared with those of conventional steel ball bearings. In this study, two types of hybrid ceramic ball bearings and two types of conventional steel ball bearings were used as test bearings. The test bearings were operated under several rotational speeds and axial loads. The radial and the axial vibrations on the outer ring of each test bearing were detected by an accelerometer. The vibrations were examined by using an FFT analyzer. From the experimental results, analysis and discussion, the vibration characteristics of hybrid ceramic ball bearings, compared with those of conventional steel ball bearings, are explained.

  20. Wave Journal Bearing. Part 1: Analysis

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin

    1995-01-01

    A wave journal bearing concept features a waved inner bearing diameter of the non-rotating bearing side and it is an alternative to the plain journal bearing. The wave journal bearing has a significantly increased load capacity in comparison to the plain journal bearing operating at the same eccentricity. It also offers greater stability than the plain circular bearing under all operating conditions. The wave bearing's design is relatively simple and allows the shaft to rotate in either direction. Three wave bearings are sensitive to the direction of an applied stationary side load. Increasing the number of waves reduces the wave bearing's sensitivity to the direction of the applied load relative to the wave. However, the range in which the bearing performance can be varied decreases as the number of waves increases. Therefore, both the number and the amplitude of the waves must be properly selected to optimize the wave bearing design for a specific application. It is concluded that the stiffness of an air journal bearing, due to hydrodynamic effect, could be doubled and made to run stably by using a six or eight wave geometry with a wave amplitude approximately half of the bearing radial clearance.

  1. Fuzzy control of magnetic bearings

    NASA Technical Reports Server (NTRS)

    Feeley, J. J.; Niederauer, G. M.; Ahlstrom, D. J.

    1991-01-01

    The use of an adaptive fuzzy control algorithm implemented on a VLSI chip for the control of a magnetic bearing was considered. The architecture of the adaptive fuzzy controller is similar to that of a neural network. The performance of the fuzzy controller is compared to that of a conventional controller by computer simulation.

  2. Inserts Automatically Lubricate Ball Bearings

    NASA Technical Reports Server (NTRS)

    Hager, J. A.

    1983-01-01

    Inserts on ball-separator ring of ball bearings provide continuous film of lubricant on ball surfaces. Inserts are machined or molded. Small inserts in ball pockets provide steady supply of lubricant. Technique is utilized on equipment for which maintenance is often poor and lubrication interval is uncertain, such as household appliances, automobiles, and marine engines.

  3. High performance rolling element bearing

    NASA Technical Reports Server (NTRS)

    Bursey, Jr., Roger W. (Inventor); Olinger, Jr., John B. (Inventor); Owen, Samuel S. (Inventor); Poole, William E. (Inventor); Haluck, David A. (Inventor)

    1993-01-01

    A high performance rolling element bearing (5) which is particularly suitable for use in a cryogenically cooled environment, comprises a composite cage (45) formed from glass fibers disposed in a solid lubricant matrix of a fluorocarbon polymer. The cage includes inserts (50) formed from a mixture of a soft metal and a solid lubricant such as a fluorocarbon polymer.

  4. Gradient Tempering Of Bearing Races

    NASA Technical Reports Server (NTRS)

    Parr, Richardson A.

    1991-01-01

    Gradient-tempering process increases fracture toughness and resistance to stress-corrosion cracking of ball-bearing races made of hard, strong steels and subject to high installation stresses and operation in corrosive media. Also used in other applications in which local toughening of high-strength/low-toughness materials required.

  5. Intelligent Engine Systems: Bearing System

    NASA Technical Reports Server (NTRS)

    Singh, Arnant P.

    2008-01-01

    The overall requirements necessary for sensing bearing distress and the related criteria to select a particular rotating sensor were established during the phase I. The current phase II efforts performed studies to evaluate the Robustness and Durability Enhancement of the rotating sensors, and to design, and develop the Built-in Telemetry System concepts for an aircraft engine differential sump. A generic test vehicle that can test the proposed bearing diagnostic system was designed, developed, and built. The Timken Company, who also assisted with testing the GE concept of using rotating sensors for the differential bearing diagnostics during previous phase, was selected as a subcontractor to assist General Electric (GE) for the design, and procurement of the test vehicle. A purchase order was prepared to define the different sub-tasks, and deliverables for this task. The University of Akron was selected to provide the necessary support for installing, and integrating the test vehicle with their newly designed test facility capable of simulating the operating environment for the planned testing. The planned testing with good and damaged bearings will be on hold pending further continuation of this effort during next phase.

  6. Satellite monitoring of black bear.

    NASA Technical Reports Server (NTRS)

    Craighead, J. J.; Craighead, F. C., Jr.; Varney, J. R.; Cote, C. E.

    1971-01-01

    Description of a feasibility experiment recently performed to test the use of a satellite system for telemetering environmental and physiological data from the winter den of a 'hibernating' black bear, Ursus americanus. The instrumentation procedure and evaluations of the equipment performance and sensory data obtained are discussed in detail.

  7. Robust and intelligent bearing estimation

    SciTech Connect

    Claassen, J.P.

    1998-07-01

    As the monitoring thresholds of global and regional networks are lowered, bearing estimates become more important to the processes which associate (sparse) detections and which locate events. Current methods of estimating bearings from observations by 3-component stations and arrays lack both accuracy and precision. Methods are required which will develop all the precision inherently available in the arrival, determine the measurability of the arrival, provide better estimates of the bias induced by the medium, permit estimates at lower SNRs, and provide physical insight into the effects of the medium on the estimates. Initial efforts have focused on 3-component stations since the precision is poorest there. An intelligent estimation process for 3-component stations has been developed and explored. The method, called SEE for Search, Estimate, and Evaluation, adaptively exploits all the inherent information in the arrival at every step of the process to achieve optimal results. In particular, the approach uses a consistent and robust mathematical framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, and to withdraw metrics helpful in choosing the best estimate(s) or admitting that the bearing is immeasurable. The approach is conceptually superior to current methods, particular those which rely on real values signals. The method has been evaluated to a considerable extent in a seismically active region and has demonstrated remarkable utility by providing not only the best estimates possible but also insight into the physical processes affecting the estimates. It has been shown, for example, that the best frequency at which to make an estimate seldom corresponds to the frequency having the best detection SNR and sometimes the best time interval is not at the onset of the signal. The method is capable of measuring bearing dispersion, thereby withdrawing the bearing bias as a function of frequency

  8. Himalayan black bear mauling: offense or defense?

    PubMed

    Thakur, Jagdeep Singh; Mohan, Chander; Sharma, Dev R

    2007-01-01

    The Asiatic Black Bear (Ursus thibetanus or Selenarctos thibetanus), also known as the Tibetan black bear, the Himalayan black bear, or the moon bear is a omnivorous mammal. This animal is declared threatened animal and rarely comes in human contact. Recent decrease in forest area has, however, increased the chances of bear-human interaction, hence causing injuries to humans. There is only one published report in English literature on Himalayan black bear mauling. We present 5 cases referred to our department over a period of 1 year. PMID:17606040

  9. TOOL ASSEMBLY WITH BI-DIRECTIONAL BEARING

    DOEpatents

    Longhurst, G.E.

    1961-07-11

    A two-direction motion bearing which is incorporated in a refueling nuclear fuel element trsnsfer tool assembly is described. A plurality of bi- directional bearing assembliesare fixed equi-distantly about the circumference of the transfer tool assembly to provide the tool assembly with a bearing surface- for both axial and rotational motion. Each bi-directional bearing assembly contains a plurality of circumferentially bulged rollers mounted in a unique arrangement which will provide a bearing surface for rotational movement of the tool assembly within a bore. The bi-direc tional bearing assembly itself is capable of rational motion and thus provides for longitudinal movement of the tool assembly.

  10. Alaskan brown bears, humans, and habituation

    USGS Publications Warehouse

    Smith, Thomas; Herrero, Stephen; DeBruyn, Terry D.

    2005-01-01

    We present a new paradigm for understanding habituation and the role it plays in brown bear (Ursus arctos) populations and interactions with humans in Alaska. We assert that 3 forms of habituation occur in Alaska: bear-to-bear, bear-to-human, and human-to-bear. We present data that supports our theory that bear density is an important factor influencing a bear’s overt reaction distance (ORD); that as bear density increases, overt reaction distance decreases, as does the likelihood of bear– human interactions. We maintain that the effects of bear-to-bear habituation are largely responsible for not only shaping bear aggregations but also for creating the relatively safe environment for bear viewing experienced at areas where there are high densities of brown bears. By promoting a better understanding of the forces that shape bear social interactions within populations and with humans that mingle with them, we can better manage human activities and minimize bear–human conflict.

  11. Hybrid bearings for turbopumps and the like

    NASA Technical Reports Server (NTRS)

    Justak, John F. (Inventor); Owens, Gregg R. (Inventor)

    1994-01-01

    In rocket engines power is usually obtained by burning fuel and oxidizer which are mixed, pressurized, and directed to a combustion chamber by means of turbopumps. Roller bearings are generally used in these turbopumps, but because of bearing demands hydrostatic bearings were proposed. The use of such bearings is quite feasible because during flight hydrostatic lubrication can reduce roller bearing wear. A disadvantage of such proposals is that during startup, acceleration, and shutdown high pressure fluids are not available for hydrostatic bearings. The fluid lubrication film is not always present in bearings of turbopumps. During these periods a second bearing is required to carry the load. This requirement suggests the use of hybrid bearings in rocket engine turbopumps. Such duplex bearings were provided, but when their inner races are keyed to the shaft or journal two of them are required. And such duplex bearings do not wear evenly. A hybrid hydrostatic-rolling element bearing was provided wherein the rolling element bearing is locked on the stationary housing rather than on the rotating journal.

  12. Journal and Wave Bearing Impedance Calculation Software

    NASA Technical Reports Server (NTRS)

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  13. Short-bearing approximation for full journal bearings

    NASA Technical Reports Server (NTRS)

    Ocvirk, F W

    1952-01-01

    A short-bearing approximation of pressure distribution in the oil film is presented which is an extension of the pressure-distribution function of Michell and Cardullo and includes end-leakage effects. Equations giving applied load, attitude angle, location and magnitude of peak film pressure, friction, and required oil flow rate as functions of the eccentricity ratio are also given. The capacity number, a basic non dimensional quantity resulting from this analysis is the product of the Sommerfeld number and the square of the length-diameter ratio. Curves determined by this analysis are compared with previously published experimental data and theoretical curves of Sommerfeld and Cameron and Wood. Conclusions reached indicate that this approximation is of practical value for analysis of short bearings.

  14. Mobile bearing and fixed bearing total knee arthroplasty

    PubMed Central

    Dolfin, Marco; Saccia, Francesco

    2016-01-01

    The mobile bearing (MB) concept in total knee arthroplasty (TKA) was developed as an alternative to fixed bearing (FB) implants in order to reduce wear and improve range of motion (ROM), especially focused on younger patients. Unfortunately, its theoretical advantages are still controversial. In this paper we exhibit a review of the more recent literature available comparing FB and MB designs in biomechanical and clinical aspects, including observational studies, clinical trials, national and international registries analyses, randomized controlled trials, meta-analyses and Cochrane reviews. Except for some minor aspects, none of the studies published so far has reported a significant improvement related to MBs regarding patient satisfaction, clinical, functional and radiological outcome or medium and long-term survivorship. Thus the presumed superiority of MBs over FBs appears largely inconsistent. The routine use of MB is not currently supported by adequate evidences; implant choice should be therefore made on the basis of other factors, including cost and surgeon experience. PMID:27162777

  15. Effects of bearing deadbands on bearing loads and rotor stability

    NASA Technical Reports Server (NTRS)

    1984-01-01

    A generic model of a turbopump, simplified to bring out these effects is examined. This model demonstrates that bearing deadbands which are of the same order of magnitude or larger than the center-of-mass offset of a rotor due to mass imbalances cause significantly different dynamic behavior than would be expected of a linear, dynamical system. This fundamentally nonlinear behavior yields altered stability characteristics and altered bearing loading tendencies. It is shown that side forces can enhance system stability in the small, i.e., as long as the mass imbalance does not exceed some thresholds value or as long as no large, impulsive disturbances cause the motion to depart significantly from the region of stability. Limit cycles are investigated in this report and techniques for determining these limit cycles are developed. These limit cycles are the major source of bearing loading and appear in both synchronous and nonsynchronous forms. The synchronous limit cycles are driven by rotor imbalances. The nonsynchronous limit cycles (also called subsynchronous whirls) are self-excited and are the sources of instability.

  16. Improved transducer for squeeze-film bearings

    NASA Technical Reports Server (NTRS)

    Hoogenbloom, L.

    1971-01-01

    Transducer amplifies vibrations produced by piezoelectric drivers, creating greater amplitudes than were possible with direct drive devices. Drivers isolated from bearing surfaces result in bearings with high axial load capacity and stiffness, thus, wear on ceramic cylinders is reduced.

  17. Rolling Element Bearing Stiffness Matrix Determination (Presentation)

    SciTech Connect

    Guo, Y.; Parker, R.

    2014-01-01

    Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.

  18. A Preliminary Foil Gas Bearing Performance Map

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Radil, Kevin C.; Bruckner, Robert J.; Howard, S. Adam

    2006-01-01

    Recent breakthrough improvements in foil gas bearing load capacity, high temperature tribological coatings and computer based modeling have enabled the development of increasingly larger and more advanced Oil-Free Turbomachinery systems. Successful integration of foil gas bearings into turbomachinery requires a step wise approach that includes conceptual design and feasibility studies, bearing testing, and rotor testing prior to full scale system level demonstrations. Unfortunately, the current level of understanding of foil gas bearings and especially their tribological behavior is often insufficient to avoid developmental problems thereby hampering commercialization of new applications. In this paper, a new approach loosely based upon accepted hydrodynamic theory, is developed which results in a "Foil Gas Bearing Performance Map" to guide the integration process. This performance map, which resembles a Stribeck curve for bearing friction, is useful in describing bearing operating regimes, performance safety margins, the effects of load on performance and limiting factors for foil gas bearings.

  19. Happy Birthday Smokey Bear from Joe Acaba

    NASA Video Gallery

    Expedition 32 Flight Engineer Joe Acaba wishes Smokey Bear a Happy Birthday. For 68 years Smokey Bear has been promoting fire safety and prevention through the message, “Only You Can Prevent Wild...

  20. Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

    USGS Publications Warehouse

    Hopkins, John B., III; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

    2012-01-01

    We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

  1. Mercury in polar bears from Alaska

    SciTech Connect

    Lentfer, J.W.; Galster, W.A.

    1987-04-01

    Alaskan polar bear (Ursus maritimus) muscle and liver samples collected in 1972 were analyzed for total mercury. Bears north of Alaska had more mercury than bears west of Alaska. The only difference between young and adult animals was in the northern area where adults had more mercury in liver tissue than young animals. Levels were probably not high enough to be a serious threat to bears.

  2. Research In Diagnosing Bearing Defects From Vibrations

    NASA Technical Reports Server (NTRS)

    Zoladz, T.; Earhart, E.; Fiorucci, T.

    1995-01-01

    Report describes research in bearing-defect signature analysis - use of vibration-signal analysis to diagnose defects in roller and ball bearings. Experiments performed on bearings in good condition and other bearings in which various parts scratched to provide known defects correlated with vibration signals. Experiments performed on highly instrumented motor-driven rotor assembly at speeds up to 10,050 r/min, using accelerometers, velocity probes, and proximity sensors mounted at various locations on assembly to measure vibrations.

  3. Human impacts on bear habitat use

    USGS Publications Warehouse

    Mattson, David J.

    1990-01-01

    : Human effects on bear habitat use are mediated through food biomass changes, bear tolerance of humans and their impacts, and human tolerance of bears. Large-scale changes in bear food biomass have been caused by conversion of wildlands and waterways to intensive human use, and by the introduction of exotic pathogens. Bears consume virtually all human foods that have been established in former wildlands, but bear use has been limited by access. Air pollution has also affected bear food biomass on a small scale and is likely to have major future impacts on bear habitat through climatic warming. Major changes in disturbance cycles and landscape mosaics wrought by humans have further altered temporal and spatial pulses of bear food production. These changes have brought short-term benefits in places, but have also added long-term stresses to most bear populations. Although bears tend to avoid humans, they will also use exotic and native foods in close proximity to humans. Subadult males and adult females are more often impelled to forage closer to humans because of their energetic predicament and because more secure sites are often preempted by adult males. Although male bears are typically responsible for most livestock predation, adult females and subadult males are more likely to be habituated to humans because they tend to forage closer to humans. Elimination of human-habituated bears predictably reduces effective carrying capacity and is more likely to be a factor in preserving bear populations where humans are present in moderate-to-high densities. If humans desire to preserve viable bear populations, they will either have to accept increased risk of injury associated with preserving habituated animals, or continue to crop habituated bears while at the same time preserving large tracts of wildlands free from significant human intrusion.

  4. Thin film superconductor magnetic bearings

    DOEpatents

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  5. Dynamics of air bearing sliders

    NASA Astrophysics Data System (ADS)

    Witelski, T. P.

    1998-03-01

    In this paper we present new results for the dynamics of a problem for the interaction of a compressible gas flow with a movable rigid surface. Compressible lubrication theory is applied to describe the dynamics of the vertical motion of air bearing sliders used in computer hard disk drives. In the limit of large bearing number we show this problem can be reduced to a nonlinear integrodifferential equation. Linear stability analysis and perturbation methods show that over the range of possible slider positions there is an infinite sequence of Hopf bifurcations yielding stable large amplitude periodic orbits. The dynamics of near-crash behavior and interaction with a moving disk surface are also addressed.

  6. Thin film superconductor magnetic bearings

    SciTech Connect

    Weinberger, B.R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft that is subject to a load (L) and rotatable around an axis of rotation, a magnet mounted to the shaft, and a stator in proximity to the shaft. The stator has a superconductor thin film assembly positioned to interact with the magnet to produce a levitation force on the shaft that supports the load (L). The thin film assembly includes at least two superconductor thin films and at least one substrate. Each thin film is positioned on a substrate and all the thin films are positioned such that an applied magnetic field from the magnet passes through all the thin films. A similar bearing in which the thin film assembly is mounted on the shaft and the magnet is part of the stator also can be constructed. 8 figs.

  7. Air Bearing Lift Pad (ABLP)

    NASA Technical Reports Server (NTRS)

    Dane, Dan H.; Blaise, Herman T.

    1968-01-01

    Typical air bearings float on air films of only a few thousandths of an inch and so will only operate above very smooth, even surfaces. For the mechanical simulation of space, the small drag of the bladder type air pads is much more than can be coped with, and the practicality of large floor areas being machined for precision air bearings is nonexistent. To enable operation above surfaces that undulate slightly or feature cracks and discontinuities, an ABLP has been developed. It consists of a rigid pad beneath which an inflatable bladder is mounted. The bladder is inflated with air which then escapes through passages into a cavity in the center of the bladder to produce the lifting energy. As the air escapes about the perimeter of the bladder, a certain degree of balance and equilibrium is imparted to the pad as it is able to move a limited weight across slightly uneven surfaces.

  8. Foil bearing lubrication theory including compressibility effects

    NASA Technical Reports Server (NTRS)

    Gorla, Rama Subba Reddy; Catalano, Daniel A.

    1987-01-01

    An analysis is presented to determine the film thickness in a foil bearing. Using the Reynolds equation and including the compressibility effects of the gas, an equation was developed applicable to the film thickness in a foil bearing. The bearing was divided into three regions, namely, the entrance region, middle region and exit region. Solutions are obtained for the film thickness in each region.

  9. Passive Thermal Management of Foil Bearings

    NASA Technical Reports Server (NTRS)

    Bruckner, Robert J. (Inventor)

    2015-01-01

    Systems and methods for passive thermal management of foil bearing systems are disclosed herein. The flow of the hydrodynamic film across the surface of bearing compliant foils may be disrupted to provide passive cooling and to improve the performance and reliability of the foil bearing system.

  10. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  11. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  12. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Bearing factors. 25.623 Section 25.623... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  13. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bearing factors. 25.623 Section 25.623... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  14. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Bearing factors. 29.623 Section 29.623... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.623 Bearing factors. (a... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  15. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Bearing factors. 29.623 Section 29.623... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.623 Bearing factors. (a... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  16. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Bearing factors. 27.623 Section 27.623... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  17. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  18. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Bearing factors. 27.623 Section 27.623... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  19. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Bearing factors. 29.623 Section 29.623... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.623 Bearing factors. (a... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  20. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Bearing factors. 29.623 Section 29.623... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.623 Bearing factors. (a... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  1. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Bearing factors. 23.623 Section 23.623... Bearing factors. (a) Each part that has clearance (free fit), and that is subject to pounding or vibration, must have a bearing factor large enough to provide for the effects of normal relative motion. (b)...

  2. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bearing factors. 29.623 Section 29.623... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.623 Bearing factors. (a... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  3. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Bearing factors. 25.623 Section 25.623... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  4. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Bearing factors. 23.623 Section 23.623... Bearing factors. (a) Each part that has clearance (free fit), and that is subject to pounding or vibration, must have a bearing factor large enough to provide for the effects of normal relative motion. (b)...

  5. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Bearing factors. 27.623 Section 27.623... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  6. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bearing factors. 23.623 Section 23.623... Bearing factors. (a) Each part that has clearance (free fit), and that is subject to pounding or vibration, must have a bearing factor large enough to provide for the effects of normal relative motion. (b)...

  7. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  8. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bearing factors. 27.623 Section 27.623... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  9. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Bearing factors. 23.623 Section 23.623... Bearing factors. (a) Each part that has clearance (free fit), and that is subject to pounding or vibration, must have a bearing factor large enough to provide for the effects of normal relative motion. (b)...

  10. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Bearing factors. 25.623 Section 25.623... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  11. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Bearing factors. 25.623 Section 25.623... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  12. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Bearing factors. 27.623 Section 27.623... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  13. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Bearing factors. 23.623 Section 23.623... Bearing factors. (a) Each part that has clearance (free fit), and that is subject to pounding or vibration, must have a bearing factor large enough to provide for the effects of normal relative motion. (b)...

  14. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  15. Steels For Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1988-01-01

    Bearing lives increased by attention to details of processing and applications. NASA technical memorandum discusses selection of steels for long-life rolling-element bearings. After brief review of advances in manufacturing, report discusses effect of cleanliness of bearing material on fatigue in rolling element. Also discusses fracture toughnesses of through-hardened and case-hardened materials.

  16. Cryptosporidiosis in a black bear in Virginia.

    PubMed

    Duncan, R B; Caudell, D; Lindsay, D S; Moll, H D

    1999-04-01

    Cryptosporidiosis has not been previously reported in black bears in North America, either free-roaming or captive. However, oocysts have been documented in two captive Malayan sun bears (Helarctos malayanus) located in zoological parks in Taiwan. Developmental stages of Cryptosporidium parvum were observed in tissue sections from the small intestine of a black bear cub found dead in Virginia (USA). PMID:10231767

  17. Cool Polar Bears: Dabbing on the Texture

    ERIC Educational Resources Information Center

    O'Connell, Jean

    2011-01-01

    In this article, the author describes how her second-graders created their cool polar bears. The students used the elements of shape and texture to create the bears. They used Monet's technique of dabbing paint so as to give the bear some texture on his fur.

  18. Magnetic bearings for vibration control

    NASA Technical Reports Server (NTRS)

    Schweitzer, G.

    1985-01-01

    A survey is presented on the research of the Institute of Mechanics of the ETH in the field of vibration control with magnetic bearings. It shows a method for modelling an elastic rotor so that it can be represented by a low order model amenable to control techniques. It deals with the control law and spill-over effects, and it also discusses experimental results for an active resonance damper.

  19. Rolling element bearings in space

    NASA Technical Reports Server (NTRS)

    Kannel, J. W.; Dufrane, K. F.

    1986-01-01

    Some of the advances in tribology that have been associated with aerospace mechanisms are discussed. The needs of aerospace have been the dominant forces leading to improvements in understanding and applying tribology technology. In the past two decades improvements in understanding bearing torque, elastohydrodynamic lubrication, lubricant distribution, cage stability, and transfer film lubricants have been made. It is anticipated that further developments will be made in response to future aerospace requirements.

  20. Fault Tolerant Homopolar Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert

    2003-01-01

    Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic bearing is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which adjust the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher bearing contact following pole failures and (b) re-levitation off of the catcher bearings following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.

  1. Cannibalism and predation on black bears by grizzly bears in the Yellowstone ecosystem, 1975-1990

    USGS Publications Warehouse

    Mattson, D.J.; Knight, R.R.; Blanchard, B.M.

    1992-01-01

    We documented one instance of an adult male grizzly bear preying upon a black bear and four instances where circumstantial evidence suggested that grizzly bears (two cubs-of-the-year, one yearling female that was injured, and one adult male) had been preyed upon by conspecifics. We also examined feces of grizzly bears for bear remains. Remains of bears tended to be more common in spring feces and did not differ in frequency between early and late years of the study. Our observations generally support existing hypotheses concerning cannibalism among bears.

  2. Equations For Elastohydrodynamic Lubrication Of Bearings

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1993-01-01

    Equation for thickness of elastohydrodynamic (EHD) lubricant film in rolling-element bearing reduced to simplified form involving only inside and outside diameters of bearing, speed of rotation, parameter related to type of lubricant, and viscosity of lubricant at temperature of bearing. In addition, experimentally derived graph of EHD-film-thickness-reduction factor as function of contact-lubricant-flow number. Accounts for lubricant starvation within Hertzian contact. Graph relating ratio of minimum film thickness to composite roughness of bearing surfaces and to lubrication-life correction factor also provided. Life-correction factor used to determine resultant life of bearing.

  3. Heuristic explanation of journal bearing instability

    NASA Technical Reports Server (NTRS)

    Crandall, S. H.

    1982-01-01

    A fluid-filled journal bearing is viewed as a powerful pump circulating fluid around the annular space between the journal and the bearing. A small whirling motion of the journal generates a wave of thickness variation progressing around the channel. The hypothesis that the fluid flow drives the whirl whenever the mean of the pumped fluid velocity is greater than the peripheral speed of the thickness variation wave is discussed and compared with other simple explanations of journal bearing instability. It is shown that for non-cavitation long bearings the hypothesis predicts instability onset correctly for unloaded bearings but gradually overpredicts the onset speed as the load is increased.

  4. Valve assembly having remotely replaceable bearings

    DOEpatents

    Johnson, Evan R.; Tanner, David E.

    1980-01-01

    A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings.

  5. Ball Bearing Analysis with the ORBIS Tool

    NASA Technical Reports Server (NTRS)

    Halpin, Jacob D.

    2016-01-01

    Ball bearing design is critical to the success of aerospace mechanisms. Key bearing performance parameters, such as load capability, stiffness, torque, and life all depend on accurate determination of the internal load distribution. Hence, a good analytical bearing tool that provides both comprehensive capabilities and reliable results becomes a significant asset to the engineer. This paper introduces the ORBIS bearing tool. A discussion of key modeling assumptions and a technical overview is provided. Numerous validation studies and case studies using the ORBIS tool are presented. All results suggest the ORBIS code closely correlates to predictions on bearing internal load distributions, stiffness, deflection and stresses.

  6. Chromatographic (TLC) differentiation of grizzly bear and black bear scats

    USGS Publications Warehouse

    Picton, Harold D.; Kendall, Katherine C.

    1994-01-01

    While past work concluded that thin-layer chromatography (TLC) was inadequate for the separation of grizzly (Ursus arctos horribilis) and black bear (U. americanus) scats, our study found differences adequate for species separation. A key was constructed using 19 of 40 data points recorded on each(N)=356 profiles of 178) know-species scat. Accuracy was best for late summer scats (94%). Methods for specimen preparation, analysis, and reading the TLC profiles are discussed. Factors involved in scat variation were tested.

  7. Lubrication for high load duplex bearings

    SciTech Connect

    Steinhoff, R.G.

    1997-08-01

    Three ES and H-compatible lubricants (Environment, Safety and Health) for high load duplex bearing applications were evaluated and compared against trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon) which is an ozone-depleting solvent. Bearings with Supercritical CO{sub 2} deposition of PTFE extracted from Vydax AR/IPA, bearings with titanium carbide coated balls, and bearings with diamond-like carbon races and retainers were evaluated. Bearings with Supercritical CO{sub 2} deposition of PTFE from Vydax AR/IPA performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax.

  8. Pratt and Whitney cryogenic turbopump bearing experience

    NASA Technical Reports Server (NTRS)

    Poole, W. E.; Bursey, R. W., Jr.

    1988-01-01

    Successful, reusable bearings require lubrication, traditionally, a transfer film from sacrificial cage wear. Early testing included materials screening programs to identify suitable cryogenic cage materials. A specially developed element tester that simulated the function of a ball bearing cage was used. Suitable materials must provide lubrication with an acceptably low wear rate, without abrading contacting surfaces. The most promising materials were tested in full scale bearings at speeds up to 4 MDN. Teflon, filled with 40 percent bronze powder, was the best performing material. A variety of bearings were designed and successfully tested in LH2 and LOX. Bearings with bronze filled Teflon cages were successfully tested for 150 hrs. In overload tests, the same design was tested for 5 hrs at maximum Hertz stresses above 450 ksi and an additional 5 hrs with a maximum Hertz stress exceeding 500 ksi. Four bearings were tested in LOX for 25 hrs, with a maximum time per bearing of 10 hrs.

  9. Contact Sensors on Ceramic Ball Bearings

    NASA Astrophysics Data System (ADS)

    Yi, Jia; Just-Agosto, Frederick; Romero, Edwar

    2002-01-01

    Integration of micro contact sensors onto a ball bearing is a critical technology necessary for on-line bearing health monitoring in an industrial harsh environment and evaluation of the bearing performance and design. The current planner fabrication methods offered by the MEMS technology restrict the possibility of integrating micro sensor onto a double contoured bearing surface in a more traditional manufacturing environment. We have developed an unique technique to directly fabricate micron-sized pressure and temperature sensors onto a miniature ceramic ball bearing. A complete fabrication process, based on sensor design, surface preparation, optimized sputtering parameters, photolithographic techniques and sensor post-treatment, is described. Pressure and temperature measurement results on a miniature ceramic ball bearing show good correlation with numerical thermal-EHL analysis and good wear resistance. Keywords: Ball Bearing, Thin film Sensor, Pressure sensor, Temperature Sensor, adhesion, wear resistance, Non-developable surface, and thermal-EHL.

  10. Design review of fluid film bearing testers

    NASA Technical Reports Server (NTRS)

    Scharrer, Joseph K.

    1993-01-01

    The designs of three existing testers (Hybrid Bearing Tester, OTV Bearing Tester, and Long Life Bearing Tester) owned by NASA were reviewed for their capability to serve as a multi-purpose cryogenic fluid film bearing tester. The primary tester function is the validation of analytical predictions for fluid film bearing steady state and dynamic performance. Evaluation criteria were established for test bearing configurations, test fluids, instrumentation, and test objectives. Each tester was evaluated with respect to these criteria. A determination was made of design improvements which would allow the testers to meet the stated criteria. The cost and time required to make the design changes were estimated. A recommendation based on the results of this study was made to proceed with the Hybrid Bearing Tester.

  11. Wave Journal Bearings Under Dynamic Loads

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.; Dimofte, Florin

    2002-01-01

    The dynamic behavior of the wave journal bearing was determined by running a three-wave bearing with an eccentrically mounted shaft. A transient analysis was developed and used to predict numerical data for the experimental cases. The three-wave journal bearing ran stably under dynamic loads with orbits well inside the bearing clearance. The orbits were almost circular and nearly free of the influence of, but dynamically dependent on, bearing wave shape. Experimental observations for both the absolute bearing-housing-center orbits and the relative bearing-housing-center-to-shaft-center orbits agreed well with the predictions. Moreover, the subsynchronous whirl motion generated by the fluid film was found experimentally and predicted theoretically for certain speeds.

  12. Evaluation of rotating, incompressibly lubricated, pressurized thrust bearings

    NASA Technical Reports Server (NTRS)

    Fleming, D. P.

    1971-01-01

    Program evaluates a series hybrid, fluid film ball bearing consisting of an orifice compensated pressurized thrust bearing in conjunction with a self-acting journal bearing. Oil viscosities corresponding to experimentally measured ball bearing outer-race temperatures were used.

  13. Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears

    PubMed Central

    Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth

    2015-01-01

    Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction. PMID:25490862

  14. Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears.

    PubMed

    Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth

    2015-03-01

    Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction. PMID:25490862

  15. Development and Evaluation of Titanium Spacesuit Bearings

    NASA Technical Reports Server (NTRS)

    Rhodes, Richard; Battisti, Brian; Ytuarte, Raymond, Jr.; Schultz, Bradley

    2016-01-01

    The Z-2 Prototype Planetary Extravehicular Space Suit Assembly is a continuation of NASA's Z-series of spacesuits, designed with the intent of meeting a wide variety of exploration mission objectives, including human exploration of the Martian surface. Incorporating titanium bearings into the Z-series space suit architecture allows us to reduce mass by an estimated 23 lbs per suit system compared to the previously used stainless steel bearing race designs, without compromising suit functionality. There are two obstacles to overcome when using titanium for a bearing race- 1) titanium is flammable when exposed to the oxygen wetted environment inside the space suit and 2) titanium's poor wear properties are often challenging to overcome in tribology applications. In order to evaluate the ignitability of a titanium space suit bearing, a series of tests were conducted at White Sands Test Facility (WSTF) that introduced the bearings to an extreme test profile, with multiple failures imbedded into the test bearings. The testing showed no signs of ignition in the most extreme test cases; however, substantial wear of the bearing races was observed. In order to design a bearing that can last an entire exploration mission (approx. 3 years), design parameters for maximum contact stress need to be identified. To identify these design parameters, bearing test rigs were developed that allow for the quick evaluation of various bearing ball loads, ball diameters, lubricants, and surface treatments. This test data will allow designers to minimize the titanium bearing mass for a specific material and lubricant combination and design around a cycle life requirement for an exploration mission. This paper reviews the current research and testing that has been performed on titanium bearing races to evaluate the use of such materials in an enriched oxygen environment and to optimize the bearing assembly mass and tribological properties to accommodate for the high bearing cycle life for an

  16. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, J.R.

    1980-05-02

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  17. Transfer Lubrication For Cryogenic Bearings

    NASA Technical Reports Server (NTRS)

    Barber, S. A.; Kannel, J. W.; Dufrane, K. F.

    1988-01-01

    Report presents evaluation of bronze-filled polytetrafluoroethylene (PTFE), known as Salox M, as cage material for ball bearings in high-pressure turbopumps for liquid oxygen. Material evaluated as potentially longer-lived replacement for glass-filled PTFE, known as Armalon. Cage transfers PTFE to balls to form solid lubricant film. However, glass fibers in glass-filled material tend to interfere with transfer. Two cage-design concepts developed; one involves metal-reinforced cage of bronze-filled PTFE; other calls for bronze-filled PTFE inserts in metal structure.

  18. Monitoring grizzly bear population trends

    USGS Publications Warehouse

    Eberhardt, L.L.; Knight, R.R.; Blanchard, B.M.

    1986-01-01

    A simple different equation model was developed to provide additional perspective on observed mortality and trend data on Yellowstone grizzly bears (Ursus arctos horribilis). Records of mortalities of adult females from 1959 to 1985 were utilized, in conjunction with data on females with cubs. The overall downward trend of observed numbers of females with cubs generally agrees with the model calculations but does not adequately reflect mortality from 1970 to 1974. The model may be useful in developing a composite index of population trend.

  19. Precision magnetic suspension linear bearing

    NASA Technical Reports Server (NTRS)

    Trumper, David L.; Queen, Michael A.

    1992-01-01

    We have shown the design and analyzed the electromechanics of a linear motor suitable for independently controlling two suspension degrees of freedom. This motor, at least on paper, meets the requirements for driving an X-Y stage of 10 Kg mass with about 4 m/sq sec acceleration, with travel of several hundred millimeters in X and Y, and with reasonable power dissipation. A conceptual design for such a stage is presented. The theoretical feasibility of linear and planar bearings using single or multiple magnetic suspension linear motors is demonstrated.

  20. Comparison of Alignment Correction Angles Between Fixed-Bearing and Mobile-Bearing UKA.

    PubMed

    Inoue, Atsuo; Arai, Yuji; Nakagawa, Shuji; Inoue, Hiroaki; Yamazoe, Shoichi; Kubo, Toshikazu

    2016-01-01

    Good outcomes have been reported with both fixed-bearing and mobile-bearing unicompartmental knee arthroplasty (UKA). However, overcorrected alignment could induce the progression of arthritis on the non-arthroplasty side. Changes of limb alignment after UKA with both types of bearings (fixed bearing: 24 knees, mobile bearing: 28 knees) were investigated. The mean difference between the preoperative standing femoral-tibial angle (FTA) and postoperative standing FTA was significantly larger in mobile bearing UKA group. In fixed-bearing UKA, there must be some laxity in MCL tension so that a 2-mm tension gauge can be inserted. In mobile-bearing UKA, appropriate MCL tension is needed to prevent bearing dislocation. This difference in MCL tension may have caused the difference in the correction angle between the groups. PMID:26264178

  1. Turbocharger bearing retention and lubrication system

    SciTech Connect

    Gutknecht, D.A.

    1991-12-31

    This patent describes exhausts gas driven turbocharger. It comprises a housing, a shaft within the housing having a longitudinal axis of rotation and a pair of ends, a compressor wheel mounted within the housing on one end of the shaft for rotation therewith, a turbine wheel mounted within the housing on the other end of the shaft for rotation therewith, means for communicating air to the compressor wheel, means for communicating exhaust gas to the turbine wheel to cause the latter to rotate the shaft and the compressor wheel mounted thereon to compress the air communicated to the compressor wheel, and bearing means mounting the shaft for rotation relative to the housing, the bearing means including a bearing outer ring, a bearing inner ring, and ball bearing elements supporting the bearing outer ring on the bearing inner ring, a bearing locating aperture in the bearing outer ring, and an elongated bearing location pin having a longitudinal axis of symmetry extending transversely to the longitudinal axis of the shaft.

  2. Current Status of Hybrid Bearing Damage Detection

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Certo, Joseph M.; Morales, Wilfredo

    2004-01-01

    Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high pressure oxidizer turbopump, on the space shuttle main engine, led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si3N4 balls. The aerospace industry is currently studying the use of hybrid bearings and naturally the failure modes of these bearings become an issue in light of the limited data available. In today s turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Since the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure. The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris, in oil, using a commercial particle counter.

  3. Interference Fit Life Factors for Roller Bearings

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2008-01-01

    The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner ring interference fit. Calculations were performed for up to seven interference fit classes for each of ten bearing sizes. Each fit was taken at tightest, average and loosest values within the fit class for RBEC-5 tolerance, thus requiring 486 separate analyses. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. The method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings based on interference fit. All calculated lives are for zero initial bearing internal clearance. Any reduction in bearing clearance due to interference fit was compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate and heavy loads and interference fits ranging from extremely light to extremely heavy and for bearing accuracy class RBEC 5 (ISO class 5). Interference fits on the inner bearing ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference fit life factors for a particular fit. The tightest fit at the high end of the RBEC-5 tolerance band defined in ANSI/ABMA shaft fit tables produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

  4. Prospects for Yellowstone grizzly bears

    USGS Publications Warehouse

    Knight, R.R.; Eberhardt, L.L.

    1987-01-01

    Recent analyses of data on the grizzly bear (Ursus arctos horribilis) population of Yellowstone National Park and its environs suggest the likelihood of a continuing decline in numbers if losses of fully adult females are not reduced. The size of the population is not known, and a simple projection model has been used to identify some inconsistencies in the available index data. Population dynamics calculations, based on Lotka's equation or a stochastic model, indicate a continuing decrease in numbers, although continued observations through radio-telemetry are needed to verify these trends. The margin between stabilizing the population and a continued decrease appears to be roughly the loss of 2 fully adult female bears per year. At present, the risk of extirpation of this population over the next 30 years appears to be small. Continued monitoring of survivorship will be needed, particularly because "recovery" of the population may be mainly characterized by a shift in the pattern of mortality, from adults to subadults, and not necessarily a reduction in absolute number of losses.

  5. Rocketdyne LOX bearing tester program

    NASA Technical Reports Server (NTRS)

    Keba, J. E.; Beatty, R. F.

    1988-01-01

    The cause, or causes, for the Space Shuttle Main Engine ball wear were unknown, however, several mechanisms were suspected. Two testers were designed and built for operation in liquid oxygen to empirically gain insight into the problems and iterate solutions in a timely and cost efficient manner independent of engine testing. Schedules and test plans were developed that defined a test matrix consisting of parametric variations of loading, cooling or vapor margin, cage lubrication, material, and geometry studies. Initial test results indicated that the low pressure pump thrust bearing surface distress is a function of high axial load. Initial high pressure turbopump bearing tests produced the wear phenomenon observed in the turbopump and identified an inadequate vapor margin problem and a coolant flowrate sensitivity issue. These tests provided calibration data of analytical model predictions to give high confidence in the positive impact of future turbopump design modification for flight. Various modifications will be evaluated in these testers, since similar turbopump conditions can be produced and the benefit of the modification will be quantified in measured wear life comparisons.

  6. The dual action gas thrust bearing - A new high load bearing concept

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1976-01-01

    The principle of utilizing hydrodynamic effects in diverging films for improving load capacity in gas thrust bearings is discussed. A new concept of dual action bearing based on that principle is described and analyzed. The potential of the new bearing is demonstrated both analytically for an infinitely long slider and by numerical solution for a flat sector shaped thrust bearing. It is shown that the dual action bearing can extend substantially the range of load carrying capacity in gas lubricated thrust bearings and improve their efficiency.

  7. Cryogenic Fluid Film Bearing Tester Development Study

    NASA Technical Reports Server (NTRS)

    Scharrer, Joseph K. (Editor); Murphy, Brian T.; Hawkins, Lawrence A.

    1993-01-01

    Conceptual designs were developed for the determination of rotordynamic coefficients of cryogenic fluid film bearings. The designs encompassed the use of magnetic and conventional excitation sources as well as the use of magnetic bearings as support bearings. Test article configurations reviewed included overhung, floating housing, and fixed housing. Uncertainty and forced response analyses were performed to assess quality of data and suitability of each for testing a variety of fluid film bearing designs. Development cost and schedule estimates were developed for each design. Facility requirements were reviewed and compared with existing MSFC capability. The recommended configuration consisted of a fixed test article housing centrally located between two magnetic bearings. The magnetic bearings would also serve as the excitation source.

  8. Magnetic bearings-state of the art

    NASA Technical Reports Server (NTRS)

    Fleming, David P.

    1991-01-01

    Magnetic bearings have existed for many years, at least in theory. Earnshaw's theorem, formulated in 1842, concerns stability of magnetic suspensions, and states that not all axes of a bearing can be stable without some means of active control. In Beam's widely referenced experiments, a tiny (1/64 in diameter) rotor was rotated to the astonishing speed of 800,000 rps while it was suspended in a magnetic field. Despite a long history, magnetic bearings have only begun to see practical application since about 1980. The development that finally made magnetic bearings practical was solid state electronics, enabling power supplies and controls to be reduced in size to where they are now comparable in volume to the bearings themselves. An attempt is made to document the current (1991) state of the art of magnetic bearings. The referenced papers are large drawn from two conferences publications published in 1988 and 1990 respectively.

  9. Magnetic bearings - State of the art

    NASA Technical Reports Server (NTRS)

    Fleming, David P.

    1993-01-01

    Magnetic bearings have existed for many years, at least in theory. Earnshaw's theorem, formulated in 1842, concerns stability of magnetic suspensions, and states that not all axes of a bearing can be stable without some means of active control. In Beam's widely referenced experiments, a tiny (1/64 in diameter) rotor was rotated to the astonishing speed of 800,000 rps while it was suspended in a magnetic field. Despite a long history, magnetic bearings have only begun to see practical application since about 1980. The development that finally made magnetic bearings practical was solid state electronics, enabling power supplies and controls to be reduced in size to where they are now comparable in volume to the bearings themselves. An attempt is made to document the current (1991) state of the art of magnetic bearings. The referenced papers are large drawn from two conferences publications published in 1988 and 1990 respectively.

  10. Magnetic Bearings for Inertial Energy Storage

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1983-01-01

    The selection of a noncontacting bearing technique with no wear out phenomena and which is vacuum compatible which is the decisive factor in selecting magnetic bearings for kinetic energy storage was investigated. Unlimited cycle life without degradation is a primary goal. Storage efficiency is a key parameter which is defined as the ratio of the energy remaining to energy stored after a fixed time interval at no load conditions. Magnetic bearings, although noncontacting, are not perfectly frictionless in that magnetic losses due to eddy currents and hysteresis can occur. Practical magnetic bearings, however, deviate from perfect symmetry and have discontinuities and asymmetric flux paths either by design or when controlled in the presence of disturbances, which cause losses. These losses can be kept smaller in the bearings than in a high power motor/generator, however, are a significant factor in selecting the magnetic bearing type.

  11. Two High-Temperature Foil Journal Bearings

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    2006-01-01

    An enlarged, high-temperature-compliant foil bearing has been built and tested to demonstrate the feasibility of such bearings for use in aircraft gas turbine engines. Foil bearings are attractive for use in some machines in which (1) speeds of rotation, temperatures, or both exceed maximum allowable values for rolling-element bearings; (2) conventional lubricants decompose at high operating temperatures; and/or (3) it is necessary or desirable not to rely on conventional lubrication systems. In a foil bearing, the lubricant is the working fluid (e.g., air or a mixture of combustion gases) in the space between the journal and the shaft in the machine in which the bearing is installed.

  12. Model Of Bearing With Hydrostatic Damper

    NASA Technical Reports Server (NTRS)

    Goggin, David G.

    1991-01-01

    Improved mathematical model of rotational and vibrational dynamics of bearing package in turbopump incorporates effects of hydrostatic damper. Part of larger finite-element model representing rotational and vibrational dynamics of rotor and housing of pump. Includes representations of deadband and nonlinear stiffness and damping of ball bearings, nonlinear stiffness and damping of hydrostatic film, and stiffness of bearing support. Enables incorporation of effects of hydrostatic damper into overall rotor-dynamic mathematical model without addition of mathematical submodel of major substructure.

  13. Teflon lubrication of liquid oxygen turbopump bearings

    NASA Technical Reports Server (NTRS)

    Naerheim, Y.; Stocker, P. J.

    1989-01-01

    Ball bearings with glass fiber reinforced Teflon ball retainers from hot-fired liquid oxygen turbopumps were analyzed by X-ray photoelectron spectroscopy to determine the extent of Teflon transfer and/or chemical reaction at the bearing surface. No Teflon, but metal fluorides could be found on the metal surface. This indicates that Teflon decomposes and reacts with the bearing steel to form fluorides. Hence, Teflon does not appear to function directly as a lubricant under these operating conditions.

  14. Cantilever mounted resilient pad gas bearing

    NASA Technical Reports Server (NTRS)

    Etsion, I. (Inventor)

    1978-01-01

    A gas-lubricated bearing is described, employing at least one pad mounted on a rectangular cantilever beam to produce a lubricating wedge between the face of the pad and a moving surface. The load-carrying and stiffness characteristics of the pad are related to the dimensions and modulus of elasticity of the beam. The bearing is applicable to a wide variety of types of hydrodynamic bearings.

  15. Complex networks from space-filling bearings

    NASA Astrophysics Data System (ADS)

    Kranz, J. J.; Araújo, N. A. M.; Andrade, J. S.; Herrmann, H. J.

    2015-07-01

    Two-dimensional space-filling bearings are dense packings of disks that can rotate without slip. We consider the entire first family of bearings for loops of four disks and propose a hierarchical construction of their contact network. We provide analytic expressions for the clustering coefficient and degree distribution, revealing bipartite scale-free behavior with a tunable degree exponent depending on the bearing parameters. We also analyze their average shortest path and percolation properties.

  16. Complex networks from space-filling bearings.

    PubMed

    Kranz, J J; Araújo, N A M; Andrade, J S; Herrmann, H J

    2015-07-01

    Two-dimensional space-filling bearings are dense packings of disks that can rotate without slip. We consider the entire first family of bearings for loops of four disks and propose a hierarchical construction of their contact network. We provide analytic expressions for the clustering coefficient and degree distribution, revealing bipartite scale-free behavior with a tunable degree exponent depending on the bearing parameters. We also analyze their average shortest path and percolation properties. PMID:26274220

  17. Miniature tilting pad gas lubricated bearing

    SciTech Connect

    Sixsmith, H.; Swift, W.L.

    1983-12-01

    This paper describes the design and development of a miniature tilting pad gas bearing developed for use in very small turbomachines. The bearings have been developed for cryogenic turboexpanders with shaft diameters down to about 0.3 cm and rotational speeds up to one million rpm. Cryogenic expansion turbines incorporating this type of bearing should be suitable for refrigeration rates down to about 10 w.

  18. A miniature tilting pad gas lubricated bearing

    NASA Astrophysics Data System (ADS)

    Sixsmith, H.; Swift, W. L.

    1983-12-01

    This paper describes the design and development of a miniature tilting pad gas bearing developed for use in very small turbomachines. The bearings have been developed for cryogenic turboexpanders with shaft diameters down to about 0.3 cm and rotational speeds up to one million rpm. Cryogenic expansion turbines incorporating this type of bearing should be suitable for refrigeration rates down to about 10 w.

  19. A miniature tilting pad gas lubricated bearing

    NASA Technical Reports Server (NTRS)

    Sixsmith, H.; Swift, W. L.

    1983-01-01

    This paper describes the design and development of a miniature tilting pad gas bearing developed for use in very small turbomachines. The bearings have been developed for cryogenic turboexpanders with shaft diameters down to about 0.3 cm and rotational speeds up to one million rpm. Cryogenic expansion turbines incorporating this type of bearing should be suitable for refrigeration rates down to about 10 w.

  20. Powder-Metallurgical Bearings For Turbopumps

    NASA Technical Reports Server (NTRS)

    Bhat, B. N.; Humphries, T. S.; Thom, R. L.; Moxson, V.; Friedman, G. I.; Dolan, F. J.; Shipley, R. J.

    1993-01-01

    Bearings fabricated by powder metallurgy developed for use in machines subjected to extremes of temperature, rolling-contact cyclic stresses, and oxidizing or otherwise corrosive fluids. Bearings also extend operating lives of other machines in which bearings required to resist extreme thermal, mechanical, and chemical stresses. One alloy exhibiting outstanding properties was MRC-2001. Resistance to fatigue, stress corrosion cracking, and wear found superior to that of 440C stainless steel.

  1. Static forces in a superconducting magnet bearing

    SciTech Connect

    Stoye, P.; Fuchs, G.; Gawalek, W.; Goernert, P.; Gladun, A.

    1995-11-01

    Static levitation forces and stiffnesses in a superconducting bearing consisting of concentric ring magnets and a superconducting YBaCuO ring are investigated. In the field-cooled mode a levitation force of 20 N has been achieved. The axial and radial stiffnesses have values of 15 N/mm and 10 N/mm, respectively. An arrangement with two bearings supporting a high speed shaft is now under development. A possible application of superconducting magnetic bearings is flywheels for energy storage.

  2. Effect of Rolling Bearing Refurbishment and Restoration on Bearing Life and Reliability

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.; Branzai, Emanuel V.

    2005-01-01

    For nearly four decades it has been a practice in commercial and military aircraft application that rolling-element bearings removed at maintenance or overhaul be reworked and returned to service. The work presented extends previously reported bearing life analysis to consider the depth (Z(45)) to maximum shear stress (45) on stressed volume removal and the effect of replacing the rolling elements with a new set. A simple algebraic relationship was established to determine the L(10) life of bearing races subject to bearing rework. Depending on the extent of rework and based upon theoretical analysis, representative life factors (LF) for bearings subject to rework ranged from 0.87 to 0.99 the lives of new bearings. Based on bearing endurance data, 92 percent of the bearing sets that would be subject to rework would result in L(10) lives equaling and/or exceeding that predicted for new bearings with the remaining 8 percent having the potential to achieve the analytically predicted life of new bearings when one of the rings is replaced at rework.. The potential savings from bearing rework varies from 53 to 82 percent that of new bearings depending on the cost, size and complexity of the bearing.

  3. Permanent Magnetic Bearing for Spacecraft Applications

    NASA Technical Reports Server (NTRS)

    Morales, Winfredo; Fusaro, Robert; Kascak, Albert

    2008-01-01

    A permanent, totally passive magnetic bearing rig was designed, constructed, and tested. The suspension of the rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm using an air impeller. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  4. Surficial deposits in the Bear Lake Basin

    USGS Publications Warehouse

    Reheis, Marith C.; Laabs, Benjamin J.C.; Forester, Richard M.; McGeehin, John P.; Kaufman, Darrell S.; Bright, Jordon

    2005-01-01

    Mapping and dating of surficial deposits in the Bear Lake drainage basin were undertaken to provide a geologic context for interpretation of cores taken from deposits beneath Bear Lake, which sometimes receives water and sediment from the glaciated Bear River and sometimes only from the small drainage basin of Bear Lake itself. Analyses of core sediments by others are directed at (1) constructing a high-resolution climate record for the Bear Lake area during the late Pleistocene and Holocene, and (2) investigating the sources and weathering history of sediments in the drainage basin. Surficial deposits in the upper Bear River and Bear Lake drainage basins are different in their overall compositions, although they do overlap. In the upper Bear River drainage, Quaternary deposits derived from glaciation of the Uinta Range contain abundant detritus weathered from Precambrian quartzite, whereas unglaciated tributaries downstream mainly contribute finer sediment weathered from much younger, more friable sedimentary rocks. In contrast, carbonate rocks capped by a carapace of Tertiary sediments dominate the Bear Lake drainage basin.

  5. Technical Development Path for Foil Gas Bearings

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher

    2008-01-01

    Foil gas bearings are in widespread commercial use in air cycle machines, turbocompressors and microturbine generators and are emerging in more challenging applications such as turbochargers, auxiliary power units and propulsion gas turbines. Though not well known, foil bearing technology is well over fifty years old. Recent technological developments indicate that their full potential has yet to be realized. This paper investigates the key technological developments that have characterized foil bearing advances. It is expected that a better understanding of foil gas bearing development path will aid in future development and progress towards more advanced applications.

  6. Implicit Flux Feedback Control for Magnetic Bearings

    NASA Astrophysics Data System (ADS)

    Keith, Frederick Joseph

    Design and implementation of a dynamic system that includes magnetic bearings is dependent on knowledge of the relationship between the command input to the magnetic actuator and the force that the bearing actually applies to the rotor (or other structure) being controlled. Traditional designs relate the bearing coil current to the developed bearing force; unfortunately, the current-to-force relationship is not invariant to magnetic hysteresis, magnetic saturation, eddy current effects, or changes in the bearing air gap length. To overcome these limitations, an approach known as implicit flux feedback is explored. Since the gap force in a magnetic circuit is directly related to the flux in that gap, measuring the gap flux and employing it as a feedback state results in a bearing with an improved command -to-force relation which is less subject to the error sources mentioned above. Confirmation of the flux-to-force relationship is accomplished via experiments on a test apparatus specifically designed to allow simultaneous force and flux measurements on a single-axis magnetic bearing (using both laminated and solid magnetic components). Successful implementation of the flux feedback algorithm simplifies the control system design of magnetic bearing systems by providing a more accurate, well characterized actuator model, and, by overcoming such effects as hysteresis, saturation, eddy currents and gap dependence, this approach provides magnetic bearings which exhibit significantly improved dynamic performance.

  7. Superconducting bearings with levitation control configurations

    SciTech Connect

    Flom, Y.; Royston, J.D.

    1992-05-26

    This patent describes a superconducting rotating assembly. It comprises first and second bearing means comprising a material exhibiting superconducting properties; a rotatable member having two extremities aligned along a common axis; magnet means at each extremity; means for maintaining each the bearing means at a temperature where the superconducting properties are manifest; means for rotating the rotatable member; means for sensing the position of the rotatable member relative to each the bearing means; and means for controlling the levitation forces exerted on the rotatable member by each the bearing means.

  8. Fractional Whirl Motion in Wave Journal Bearings

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin; Hendricks, Robert C.

    1996-01-01

    Unloaded gas, plain journal bearings experience sub-synchronous whirl motion due to fluid film instabilities and wall contact usually occurs immediately after the onset of the whirl motion. An alternative is the wave journal bearing which significantly improves bearing stability. The predicted threshold where the sub-synchronous whirl motion starts was well confirmed by the experimental observation. In addition, both a two-wave and a three-wave journal bearing can operate free of sub-synchronous whirl motion over a large range in speeds. When the sub-synchronous whirl motion occurs, both the two-wave and three-wave bearing can run in a whirl orbit well within the bearing clearance. At large clearances and wave amplitudes a two-wave bearing, unliKe other bearings, can exhibit a sub-synchronous whirl movement at both low and high speeds, but can run extremely stable and without whirl at intermediate speeds. Moreover, in these cases, the whirl frequencies are close to a quarter of the synchronous speed. The three-wave bearing can exhibit sub-synchronous whirl motion only after a specific threshold when the speed increases and the whirl frequencies are close to half of the synchronous speed.

  9. Experimental Evaluation of Journal Bearing Stability and New Gas Bearing Material

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Dimofte, Florin

    2001-01-01

    It has been estimated that the noise levels in aircraft engine transmissions can be reduced by as much as 10 dB through the use of journal bearings. The potential benefits of lower noise levels include reduced wear, longer gear life and enhanced comfort for passengers and crew. Based on this concept the journal-thrust wave bearing was analyzed and its performance was evaluated. Numerical codes, developed over the past 30 years by Dr. Dimofte, were used to predict the performance of the bearing. The wave bearing is a fluid film bearing and therefore was analyzed using the Reynolds pressure equation. The formulation includes turbulent flow concepts and possesses a viscosity-temperature correction. The centrifugal growth of the bearing diameter and the deformation of the bearing under gear loads were also incorporated into the code. An experimental rig was developed to test the journal-thrust wave bearing.

  10. Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

    NASA Technical Reports Server (NTRS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1995-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied.

  11. Dynamic modelling and response characteristics of a magnetic bearing rotor system including auxiliary bearings

    NASA Technical Reports Server (NTRS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1993-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotor-dynamic model and assess the dynamic behavior of a magnetic bearing rotor system which includes the effects of auxiliary bearings. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic bearing. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.

  12. Gearbox Reliability Collaborative Bearing Calibration

    SciTech Connect

    van Dam, J.

    2011-10-01

    NREL has initiated the Gearbox Reliability Collaborative (GRC) to investigate the root cause of the low wind turbine gearbox reliability. The GRC follows a multi-pronged approach based on a collaborative of manufacturers, owners, researchers and consultants. The project combines analysis, field testing, dynamometer testing, condition monitoring, and the development and population of a gearbox failure database. At the core of the project are two 750kW gearboxes that have been redesigned and rebuilt so that they are representative of the multi-megawatt gearbox topology currently used in the industry. These gearboxes are heavily instrumented and are tested in the field and on the dynamometer. This report discusses the bearing calibrations of the gearboxes.

  13. Movements of Yellowstone grizzly bears

    USGS Publications Warehouse

    Blanchard, Bonnie M.; Knight, Richard R.

    1991-01-01

    Ninety-seven grizzly bears Ursus arctos horribilis were radio-located 6299 times during 1975–1987. Annual range sizes differed by sex, age, reproductive status and amount of precipitation. Females exhibited greater fidelity to seasonal and annual ranges than males. Weaned female offspring generally remained in the vicinity of the maternal range, while weaned males often made substantial movements to unexplored country. Average total home range size was 884 km2 for females and 3757 km2 for males. Males consistently exhibited greater indices of movement and range sizes than females. All cohorts had larger mean ranges during this study than during the period 1959–1969 when the population had access to open garbage dumps. Movements and elevational distribution of all cohorts were related to availability of whitebark pine Pinus albicaulis seeds. We hypothesized that females with cubs-of-the-year and yearlings were displaced from most productive habitats during seasons and years of limited food availability.

  14. Evaluation of bearing configurations using the single bearing tester in liquid nitrogen

    NASA Technical Reports Server (NTRS)

    Jett, T.; Hall, P.; Thom, R.

    1991-01-01

    Various bearing configurations were tested using the Marshall Space Flight Center single bearing tester with LN2 as the cryogenic coolant. The baseline was one Rocketdyne phase one high pressure oxidizer turbopump (HPOTP) pump end 45-mm bore bearing. The bearing configurations that were tested included a Salox/M cage configuration, a silicon nitride ball configuration, an elongated cage configuration, and a Bray 601 grease configuration.

  15. Phylogeography of mitochondrial DNA variation in brown bears and polar bears

    USGS Publications Warehouse

    Shields, Gerald F.; Adams, Deborah; Garner, Gerald; Labelle, Martine; Pietsch, Jacy; Ramsay, Malcolm; Schwartz, Charles; Titus, Kimberly; Williamson, Scott

    2000-01-01

    We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples.

  16. Active magnetic bearing-supported rotor with misaligned cageless backup bearings: A dropdown event simulation model

    NASA Astrophysics Data System (ADS)

    Halminen, Oskari; Kärkkäinen, Antti; Sopanen, Jussi; Mikkola, Aki

    2015-01-01

    Active magnetic bearings (AMB) offer considerable benefits compared to regular mechanical bearings. On the other hand, they require backup bearings to avoid damage resulting from a failure in the component itself, or in the power or control system. During a rotor-bearing contact event - when the magnetic field has disappeared and the rotor drops on the backup bearings - the structure of the backup bearings has an impact on the dynamic actions of the rotor. In this paper, the dynamics of an active magnetic bearing-supported rotor during contact with backup bearings is studied with a simulation model. Modeling of the backup bearings is done using a comprehensive cageless ball bearing model. The elasticity of the rotor is described using the finite element method (FEM) and the degrees of freedom (DOF) of the system are reduced using component mode synthesis. Verification of the misaligned cageless backup bearings model is done by comparing the simulation results against the measurement results. The verified model with misaligned cageless backup bearings is found to correspond to the features of a real system.

  17. Unbalance Response Prediction for Rotors on Ball Bearings Using Speed and Load Dependent Nonlinear Bearing Stiffness

    NASA Technical Reports Server (NTRS)

    Fleming, David P.; Poplawski, J. V.

    2003-01-01

    Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic analysis requires that bearing forces corresponding to the actual bearing deflection be utilized. For this work bearing forces were calculated by COBRA-AHS, a recently developed rolling-element bearing analysis code. Bearing stiffness was found to be a strong function of bearing deflection, with higher deflection producing markedly higher stiffness. Curves fitted to the bearing data for a range of speeds and loads were supplied to a flexible rotor unbalance response analysis. The rotordynamic analysis showed that vibration response varied nonlinearly with the amount of rotor imbalance. Moreover, the increase in stiffness as critical speeds were approached caused a large increase in rotor and bearing vibration amplitude over part of the speed range compared to the case of constant bearing stiffness. Regions of bistable operation were possible, in which the amplitude at a given speed was much larger during rotor acceleration than during deceleration. A moderate amount of damping will eliminate the bistable region, but this damping is not inherent in ball bearings.

  18. Low cost techniques for fabricating lobed bearings

    NASA Technical Reports Server (NTRS)

    Schuller, F. T.

    1968-01-01

    New low cost technique utilizes shims to create the lobes in bearing. Conventional methods of manufacture require accurate off-center grinding of the inside diameter of a bearing in a housing at various arc lengths depending on the number of lobes required.

  19. Freon 21 bearing lubrication and coolant system

    NASA Technical Reports Server (NTRS)

    Bodensieck, E. J.; Gustafson, M. J.

    1972-01-01

    Lubrication and cooling of turbopump rotor bearings by liquid Freon 21 is reported. Freon expands in rotor bearing and acts as heat sink by removing heat during warming and evaporation. Gaseous Freon is removed by vacuum pump controlling rotor chamber operation.

  20. Measuring Bearing Wear Via Weight Loss

    NASA Technical Reports Server (NTRS)

    Keba, John E.; Moore, Richard S.

    1989-01-01

    Wear in critical parts of bearings measured via amounts of weight lost during use. Technique applicable in general to bearings made of nonporous materials. Weight-loss measurements easier, faster, more precise, and less likely to damage measured parts. Weight-loss measurements performed in clean rooms and under constraint of extreme cleanliness for compatability with liquid oxygen.

  1. Self-adjusting magnetic bearing systems

    DOEpatents

    Post, R.F.

    1998-07-21

    A self-adjusting magnetic bearing automatically adjusts the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium. Complete stabilization can be obtained with the application of weak restoring forces either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. In one embodiment, a torque is generated by the approach of a slotted pole to a conducting plate. The torque actuates an assembly which varies the position of a magnetic shunt to change the force exerted by the bearing. Another embodiment achieves axial stabilization by sensing vertical displacements in a suspended bearing element, and using this information in an electrical servo system. In a third embodiment, as a rotating eddy current exciter approaches a stationary bearing, it heats a thermostat which actuates an assembly to weaken the attractive force between the two bearing elements. An improved version of an electromechanical battery utilizing the designs of the various embodiments is described. 7 figs.

  2. Lubrication of rolling-element bearings

    NASA Technical Reports Server (NTRS)

    Parker, R. J.

    1980-01-01

    The lubrication of rolling element bearings is surveyed. Emphasis is on the critical design aspects related to speed, temperature, and ambient pressure environment. Types of lubrication including grease, jets, mist, wick, and through the race are discussed. The historical development, present state of technology, and the future problems of rolling element bearing lubrication are discussed.

  3. Long-wearing TFE/metal bearings

    NASA Technical Reports Server (NTRS)

    Brass, R. A.; Gillon, W. A., Jr.

    1980-01-01

    Method for making metal/polytetrafluoroethylene (TFE) bearing surfaces embeds long-wearing layer of TFE in microscopic pits in metal. Technique has potential applications in automotive gears, ball joints, and roller chain components. Other applications are in use of unlubricated bearings in chemical, pharmaceutical, and food-processing equipment.

  4. 33 CFR 117.543 - Bear Creek.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draws of the...

  5. 33 CFR 117.543 - Bear Creek.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draw of the...

  6. 33 CFR 117.543 - Bear Creek.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draw of the...

  7. 33 CFR 117.543 - Bear Creek.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draws of the...

  8. 33 CFR 117.543 - Bear Creek.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draw of the...

  9. Methods and systems for micro bearings

    SciTech Connect

    Stalford, Harold L

    2015-01-27

    A micro drive assembly may comprise a substrate, a micro shaft oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

  10. Self-adjusting magnetic bearing systems

    DOEpatents

    Post, Richard F.

    1998-01-01

    A self-adjusting magnetic bearing automatically adjusts the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium. Complete stabilization can be obtained with the application of weak restoring forces either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. In one embodiment, a torque is generated by the approach of a slotted pole to a conducting plate. The torque actuates an assembly which varies the position of a magnetic shunt to change the force exerted by the bearing. Another embodiment achieves axial stabilization by sensing vertical displacements in a suspended bearing element, and using this information in an electrical servo system. In a third embodiment, as a rotating eddy current exciter approaches a stationary bearing, it heats a thermostat which actuates an assembly to weaken the attractive force between the two bearing elements. An improved version of an electromechanical battery utilizing the designs of the various embodiments is described.

  11. Precision instrumentation for rolling element bearing characterization

    SciTech Connect

    Marsh, Eric R.; Vigliano, Vincent C.; Weiss, Jeffrey R.; Moerlein, Alex W.; Vallance, R. Ryan

    2007-03-15

    This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must be prevented in a way that leaves the radial, axial/face, and tilt displacements free to move. Finally, the bearing must be fixtured and measured without introducing off-axis loading or other distorting influences. In the design presented here, an air bearing reference spindle with error motion of less than 10 nm rotates the inner race of the bearing under test. Noninfluencing couplings are used to prevent rotation of the bearing outer race and apply an axial preload without distorting the bearing or influencing the measurement. Capacitive displacement sensors with 2 nm resolution target the nonrotating outer race. The error motion measurement repeatability is shown to be less than 25 nm. The article closes with a discussion of how the instrument may be used to gather data with sufficient resolution to accurately estimate the contact angle of deep groove ball bearings.

  12. Magnetic perturbation inspection of inner bearing races

    NASA Technical Reports Server (NTRS)

    Barton, J. R.; Lankford, J.

    1972-01-01

    Approximately 100 inner race bearings were inspected nondestructively prior to endurance testing. Two of the bearings which failed during testing spalled at the sites of subsurface inclusions previously detected by using magnetic field perturbation. At other sites initially judged to be suspect, subsurface inclusion-nucleated cracking was observed. Inspection records and metallurgical sectioning results are presented and discussed.

  13. Methods and systems for micro bearings

    SciTech Connect

    Stalford, Harold L.

    2012-10-09

    A micro drive assembly may comprise a substrate, a micro shall oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

  14. A flexible cruciform journal bearing mount

    NASA Technical Reports Server (NTRS)

    Frost, A. E.; Geiger, W. A.

    1973-01-01

    Flexible mount achieves low roll, pitch and yaw stiffnesses while maintaining high radial stiffness by holding bearing pad in fixed relationship to deep web cruciform member and holding this member in fixed relationship to bearing support. This mount has particular application in small, high performance gas turbines.

  15. Anatomy of a bearing torque problem

    NASA Technical Reports Server (NTRS)

    Phinney, Damon D.

    1987-01-01

    In the early 1970s, an antenna despin drive was developed for MBB solar science satellite HELIOS. A problem with high bearing drag torque that was encountered on the two flight models of this drive, after successful tests were completed on twelve bearings, an engineering model, and the qualification unit is discussed.

  16. Friction coefficients of PTFE bearing liner

    NASA Technical Reports Server (NTRS)

    Daniels, C. M.

    1979-01-01

    Data discusses frictional characteristics of PTFE (polytetrafluoroethylene) under temperature extremes and in vacuum environment. Tests were also run on reduced scale hardware to determine effects of vacuum. Data is used as reference by designers of aircraft-control system rod-end bearings and for bearings used in polar regions.

  17. Bearing Tests of Magnesium-alloy Sheet

    NASA Technical Reports Server (NTRS)

    Sharp, W H; Moore, R L

    1943-01-01

    Bearing tests of AM-3S, AM-52S, and AM-C57S magnesium-alloy sheet in various thicknesses and tempers were made. Bearing yield and ultimate strengths were determined and compared for various edge distances and for various ratios of loading-pin diameter to sheet thickness. Tensile strengths were determined and ratios of average bearing yield and ultimate strength to tensile strength are given. The results of the tests indicated that ultimate bearing strengths increased with edge distances up to 1.5 to 2 times the diameter of the loading pin; that ultimate bearing strengths are a function of the ratio of pin diameter to sheet thickness; and that these properties are effected only slightly by increases in edge distance greater than 1.5 diameters.

  18. Rotor and bearing system for a turbomachine

    DOEpatents

    Lubell, Daniel; Weissert, Dennis

    2006-09-26

    A rotor and bearing system for a turbomachine. The turbomachine includes a drive shaft, an impeller positioned on the drive shaft, and a turbine positioned on the drive shaft proximate to the impeller. The bearing system comprises one gas journal bearing supporting the drive shaft between the impeller and the turbine. The area between the impeller and the turbine is an area of increased heat along the drive shaft in comparison to other locations along the drive shaft. The section of the drive shaft positioned between impeller and the turbine is also a section of the drive shaft that experiences increased stressed and load in the turbomachine. The inventive bearing machine system positions only one radial bearing in this area of increased stress and load.

  19. Development of new materials for turbopump bearings

    NASA Technical Reports Server (NTRS)

    Maurer, R. E.; Pallini, R. A.

    1985-01-01

    The life requirement for the angular contact ball bearings in the Space Shuttle Main Engine (SSME) high pressure oxygen turbopump (HPOTP) is 7.5 hours. In actual operation, significantly shorter service life was experienced. The objective is to identify bearing materials and/or materials processing techniques offering signficant potential for extending HPOTP bearing performance life. Interactive thermomechanical analysis of the HPOTP bearing-shaft system was performed with the SHABERTH computer program. Bearing fatigue life, ball-race contact stress, heat generation rate, bulk ring temperatures and circumferential stress in the inner rings were quantified as functions of radial load, thrust load and ball-race contact friction. Criteria established from the output of this analysis are being used for material candidate selection.

  20. Status of Understanding for Bearing Materials

    NASA Technical Reports Server (NTRS)

    Bamberger, E. N.

    1984-01-01

    The structural materials and potential failure modes for high technology aircraft gas turbine bearings are reviewed. Among the failure modes discussed for iron-base through-hardened bearing materials are fatigue, surface distress, and corrosion. It is shown that the sub-surface initiated rolling-contact fatigue failure mode is reasonably well understood and in most cases can be controlled by proper material selection and design. Current bearing materials provide long life and high reliability in existing applications. A new generation of materials are being developed which will provide improved fracture toughness, better corrosion resistance, and a further extension of bearing fatigue life. Bearing problems due to surface distress, caused by a variety of surface and near surface anomalies, are less well understood. This area will require the implementation of an interdisciplinary effort to improve the level of understanding of metallic surface-lubricant reactions and interactions.

  1. Status of understanding for bearing materials

    SciTech Connect

    Bamberger, E.N.

    1984-04-01

    The structural materials and potential failure modes for high technology aircraft gas turbine bearings are reviewed. Among the failure modes discussed for iron-base through-hardened bearing materials are fatigue, surface distress, and corrosion. It is shown that the sub-surface initiated rolling-contact fatigue failure mode is reasonably well understood and in most cases can be controlled by proper material selection and design. Current bearing materials provide long life and high reliability in existing applications. A new generation of materials are being developed which will provide improved fracture toughness, better corrosion resistance, and a further extension of bearing fatigue life. Bearing problems due to surface distress, caused by a variety of surface and near surface anomalies, are less well understood. This area will require the implementation of an interdisciplinary effort to improve the level of understanding of metallic surface-lubricant reactions and interactions.

  2. Conservation of the Yellowstone grizzly bear

    USGS Publications Warehouse

    Mattson, David J.; Reid, Matthew M.

    1991-01-01

    We review literature relevant to the conservation of Yellowstone's grizzly bear population and appraise the bear's long-term viability. We conclude that the population is isolated and vulnerable to epidemic perturbation and that the carrying capacity of the habitat is likely to shift downward under conditions of climate change. Viability analyses based on the assumption that future habitats will closely resemble those existing at present have limited applicability; more information is needed on the autecology of important bear foods and on the implications of landscape-scale changes for bear population dynamics. Optimism over prospects of long-term persistence for Yellowstone's grizzly bears does not seem to be warranted and management of this population should be conservative and not unduly swayed on short-term positive trends.

  3. Geology and geomorphology of Bear Lake Valley and upper Bear River, Utah and Idaho

    USGS Publications Warehouse

    Reheis, M.C.; Laabs, B.J.C.; Kaufman, D.S.

    2009-01-01

    Bear Lake, on the Idaho-Utah border, lies in a fault-bounded valley through which the Bear River flows en route to the Great Salt Lake. Surficial deposits in the Bear Lake drainage basin provide a geologic context for interpretation of cores from Bear Lake deposits. In addition to groundwater discharge, Bear Lake received water and sediment from its own small drainage basin and sometimes from the Bear River and its glaciated headwaters. The lake basin interacts with the river in complex ways that are modulated by climatically induced lake-level changes, by the distribution of active Quaternary faults, and by the migration of the river across its fluvial fan north of the present lake. The upper Bear River flows northward for ???150 km from its headwaters in the northwestern Uinta Mountains, generally following the strike of regional Laramide and late Cenozoic structures. These structures likely also control the flow paths of groundwater that feeds Bear Lake, and groundwater-fed streams are the largest source of water when the lake is isolated from the Bear River. The present configuration of the Bear River with respect to Bear Lake Valley may not have been established until the late Pliocene. The absence of Uinta Range-derived quartzites in fluvial gravel on the crest of the Bear Lake Plateau east of Bear Lake suggests that the present headwaters were not part of the drainage basin in the late Tertiary. Newly mapped glacial deposits in the Bear River Range west of Bear Lake indicate several advances of valley glaciers that were probably coeval with glaciations in the Uinta Mountains. Much of the meltwater from these glaciers may have reached Bear Lake via groundwater pathways through infiltration in the karst terrain of the Bear River Range. At times during the Pleistocene, the Bear River flowed into Bear Lake and water level rose to the valley threshold at Nounan narrows. This threshold has been modified by aggradation, downcutting, and tectonics. Maximum lake

  4. Wave journal bearing with compressible lubricant--Part 1: The wave bearing concept and a comparison to the plain circular bearing

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin

    1995-01-01

    To improve hydrodynamic journal bearing steady-state and dynamic performance, a new bearing concept, the wave journal bearing, was developed at the author's lab. This concept features a waved inner bearing diameter. Compared to other alternative bearing geometries used to improve bearing performance such as spiral or herring-bone grooves, steps, etc., the wave bearing's design is relatively simple and allows the shaft to rotate in either direction. A three-wave bearing operating with a compressible lubricant, i.e., gas is analyzed using a numerical code. Its performance is compared to a plain (truly) circular bearing over a broad range of bearing working parameters, e.g., bearing numbers from 0.01 to 100.

  5. Hydrodynamic air lubricated compliant surface bearing for an automotive gas turbine engine. 1: Journal bearing performance

    NASA Technical Reports Server (NTRS)

    Ruscitto, D.; Mccormick, J.; Gray, S.

    1978-01-01

    A 38.1 mm (1.5 inch) diameter Hydresil Compliant Surface Air Lubricated Journal Bearing was designed and tested to obtain bearing performance characteristics at both room temperature and 315 C (600 F). Testing was performed at various speeds up to 60,000 rpm with varying loads. Rotating sensors provided an opportunity to examine the film characteristics of the compliant surface bearing. In addition to providing minimum film thickness values and profiles, many other insights into bearing operation were gained such as the influence of bearing fabrication accuracy and the influence of smooth foil deflection between the bumps.

  6. Bearing tester data compilation, analysis, and reporting and bearing math modeling

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The Shaberth bearing analysis computer program was developed for the analysis of jet engine shaft/bearing systems operating above room temperature with normal hydrocarbon lubricants. It is also possible to use this tool to evaluate the shaft bearing systems operating in cryogenics. Effects such as fluid drag, radial temperature gradients, outer race misalignments and clearance changes were simulated and evaluated. In addition, the speed and preload effects on bearing radial stiffness was evaluated. The Shaberth program was also used to provide contact stresses from which contact geometry was calculated to support other analyses such as the determination of cryogenic fluid film thickness in the contacts and evaluation of surface and subsurface stresses necessary for bearing failure evaluation. This program was a vital tool for the thermal analysis of the bearing in that it provides the heat generation rates at the rolling element/race contacts for input into a thermal model of the bearing/shaft assembly.

  7. Ball bearing versus magnetic bearing reaction and momentum wheels as momentum actuators

    NASA Technical Reports Server (NTRS)

    Auer, W.

    1980-01-01

    Different bearing technologies of momentum actuators for the attitude control of satellites are compared and a guideline for the selection of the suitable momentum actuators or momentum actuator configurations to meet given mission goals with high reliability and low cost is developed. The comparison between ball bearing and magnetic bearing momentum actuators shows that given mission requirements can be economically met by employing the ball bearing technology without decreasing reliability and lifetime. However, for some special mission requirements, such as 'zero friction at zero speed,' fine pointing (met by vernier gimballing), and/or active damping, magnetic bearings may be advantageous. This makes it evident that magnetic bearing technology will not replace ball bearing technology for momentum actuators, but will supplement it for some special mission requirements.

  8. Tribology of hard bearing coatings

    SciTech Connect

    Santavy, A.P.; Scattergood, R.O.

    1996-12-31

    The performance of a linear sliding contact bearing is dictated by a frictional effect called stiction. Stiction exists when the static coefficient of friction is substantially higher than the dynamic coefficient. Stiction can cause chatter or jerky motion when attempting to move a slide at low speed. The force required to overcome static friction will cause deflection in the structure of the machine. If the dynamic coefficient is less than the static coefficient, when the slide breaks loose the friction force is suddenly reduced and there is an excess force on the slide and it is accelerated by this unbalanced force. As the slide moves relative to the rest of the structure the force due to the deflection of the structure is relieved. The inertia of the slide will carry it beyond the equilibrium point until the force on the slide is less than that required to overcome dynamic friction and the slide will stop. This process repeats. At high speeds, chatter does not occur because the velocity due to the suddenly unbalanced force at breakaway is small compared to the overall velocity so that the slide never comes to rest. For friction materials with a dynamic coefficient that is not less than static, stiction induced chatter does not occur because there is no excess force when the slide breaks away.

  9. Vibration model of rolling element bearings in a rotor-bearing system for fault diagnosis

    NASA Astrophysics Data System (ADS)

    Cong, Feiyun; Chen, Jin; Dong, Guangming; Pecht, Michael

    2013-04-01

    Rolling element bearing faults are among the main causes of breakdown in rotating machines. In this paper, a rolling bearing fault model is proposed based on the dynamic load analysis of a rotor-bearing system. The rotor impact factor is taken into consideration in the rolling bearing fault signal model. The defect load on the surface of the bearing is divided into two parts, the alternate load and the determinate load. The vibration response of the proposed fault signal model is investigated and the fault signal calculating equation is derived through dynamic and kinematic analysis. Outer race and inner race fault simulations are realized in the paper. The simulation process includes consideration of several parameters, such as the gravity of the rotor-bearing system, the imbalance of the rotor, and the location of the defect on the surface. The simulation results show that different amplitude contributions of the alternate load and determinate load will cause different envelope spectrum expressions. The rotating frequency sidebands will occur in the envelope spectrum in addition to the fault characteristic frequency. This appearance of sidebands will increase the difficulty of fault recognition in intelligent fault diagnosis. The experiments given in the paper have successfully verified the proposed signal model simulation results. The test rig design of the rotor bearing system simulated several operating conditions: (1) rotor bearing only; (2) rotor bearing with loader added; (3) rotor bearing with loader and rotor disk; and (4) bearing fault simulation without rotor influence. The results of the experiments have verified that the proposed rolling bearing signal model is important to the rolling bearing fault diagnosis of rotor-bearing systems.

  10. Grease selection for sealed roll neck bearings

    SciTech Connect

    Schrama, R.C.; Vickerman, R.T.; Bender, C.P.

    1995-09-01

    During the 1990`s, a revolution took place in the steel industry with respect to lubricant usage, maintenance costs and the environment. The 4-row taper roller bearings that are used in rolling mills on the work roll necks have been historically lubricated with grease from a centralized grease system, pre-packed with grease at each roll change, or fed with oil from mist or air-oil system. Steel mills are being forced to reduce lubricant consumption to reduce maintenance costs, decrease the costs for the disposal of sludges created from the spent greases and reduce the amount of sludge that was created. The sealed bearing became an avenue for accomplishing these objectives. The open 4-row taper roller bearing was redesigned to accommodate seals. The bearing was pre-packed with grease and put into service without any grease replenishment for up to 22 months operation time. The selection of the grease to provide optimum operating characteristics for the lubricant and the bearing is one of the critical elements to the success of the bearing design. This paper reviews the critical properties that are necessary in the grease for the lubricant to provide the correct tribological functions in the bearing. This includes wear of the rollers and raceways, seal lip and surface wear, heat generation during rotation and under load, corrosion resistance, resistance to shearing during the working life of the grease and resistance to water contamination.

  11. Intelligent monitoring of ball bearing conditions

    NASA Astrophysics Data System (ADS)

    Liu, T. I.; Mengel, J. M.

    1992-09-01

    Ball bearings are widely used in various kinds of robots, manufacturing machines, and equipment. In order to enhance productivity and improve product quality, an on-line monitoring system is essential to check the status of ball bearings. In this work, peak amplitude in the frequency domain, peak RMS, and the power spectrum were used as indirect indices to develop a system for monitoring and classifying ball bearing defects. These indices were then processed by artificial neural networks. Six different cases of ball bearing states were observed. The data from these observations were then input into neural networks with different architectures to train these neural networks in a learning process. All the trained neural networks are capable of distinguishing the normal bearings from defective bearings with a 100 percent success rate. They can also classify the bearing conditions into six different states with a success rate of up to 97 per cent. The effects of training set sizes and neural network structures on the monitoring performance have also been investigated.

  12. Genomic sequencing of Pleistocene cave bears

    SciTech Connect

    Noonan, James P.; Hofreiter, Michael; Smith, Doug; Priest, JamesR.; Rohland, Nadin; Rabeder, Gernot; Krause, Johannes; Detter, J. Chris; Paabo, Svante; Rubin, Edward M.

    2005-04-01

    Despite the information content of genomic DNA, ancient DNA studies to date have largely been limited to amplification of mitochondrial DNA due to technical hurdles such as contamination and degradation of ancient DNAs. In this study, we describe two metagenomic libraries constructed using unamplified DNA extracted from the bones of two 40,000-year-old extinct cave bears. Analysis of {approx}1 Mb of sequence from each library showed that, despite significant microbial contamination, 5.8 percent and 1.1 percent of clones in the libraries contain cave bear inserts, yielding 26,861 bp of cave bear genome sequence. Alignment of this sequence to the dog genome, the closest sequenced genome to cave bear in terms of evolutionary distance, revealed roughly the expected ratio of cave bear exons, repeats and conserved noncoding sequences. Only 0.04 percent of all clones sequenced were derived from contamination with modern human DNA. Comparison of cave bear with orthologous sequences from several modern bear species revealed the evolutionary relationship of these lineages. Using the metagenomic approach described here, we have recovered substantial quantities of mammalian genomic sequence more than twice as old as any previously reported, establishing the feasibility of ancient DNA genomic sequencing programs.

  13. Space Telescope Fine Guidance Sensor Bearing Anomaly

    NASA Technical Reports Server (NTRS)

    Loewenthal, S.; Esper, J.; Pan, J.; Decker, J.

    1996-01-01

    Early in 1993, a servo motor within one of three Fine Guidance Sensors (FGS) aboard the Hubble Space Telescope (HST) reached stall torque levels on several occasions. Little time was left to plan replacement during the first servicing mission, scheduled at the end of '93. Accelerated bearing life tests confirmed that a small angle rocking motion, known as Coarse Track (CT), accelerated bearing degradation. Saturation torque levels were reached after approximately 20 million test cycles, similar to the flight bearings. Reduction in CT operation, implemented in flight software, extended FGS life well beyond the first servicing mission. However in recent years, bearing torques have resumed upward trends and together with a second, recent bearing torque anomaly has necessitated a scheduled FGS replacement during the upcoming second servicing mission in '97. The results from two series of life tests to quantify FGS bearing remaining life, discussion of bearing on-orbit performance, and future plans to service the FGS servos are presented in this paper.

  14. Past Performance analysis of HPOTP bearings

    NASA Technical Reports Server (NTRS)

    Bhat, B. N.; Dolan, F. J.

    1982-01-01

    The past performance analysis conducted on three High Pressure Oxygen Turbopump (HPOTP) bearings from the Space Shuttle Main Engine is presented. Metallurgical analysis of failed bearing balls and races, and wear track and crack configuration analyses were carried out. In addition, one bearing was tested in laboratory at very high axial loads. The results showed that the cracks were surface initiated and propagated into subsurface locations at relatively small angles. Subsurface cracks were much more extensive than was appeared on the surface. The location of major cracks in the races corresponded to high radial loads rather than high axial loads. There was evidence to suggest that the inner races were heated to elevated temperatures. A failure scenario was developed based on the above findings. According to this scenario the HPOTP bearings are heated by a combination of high loads and high coefficient of friction (poor lubrication). Different methods of extending the HPOTP bearing life are also discussed. These include reduction of axial loads, improvements in bearing design, lubrication and cooling, and use of improved bearing materials.

  15. Passive Magnetic Bearing With Ferrofluid Stabilization

    NASA Technical Reports Server (NTRS)

    Jansen, Ralph; DiRusso, Eliseo

    1996-01-01

    A new class of magnetic bearings is shown to exist analytically and is demonstrated experimentally. The class of magnetic bearings utilize a ferrofluid/solid magnet interaction to stabilize the axial degree of freedom of a permanent magnet radial bearing. Twenty six permanent magnet bearing designs and twenty two ferrofluid stabilizer designs are evaluated. Two types of radial bearing designs are tested to determine their force and stiffness utilizing two methods. The first method is based on the use of frequency measurements to determine stiffness by utilizing an analytical model. The second method consisted of loading the system and measuring displacement in order to measure stiffness. Two ferrofluid stabilizers are tested and force displacement curves are measured. Two experimental test fixtures are designed and constructed in order to conduct the stiffness testing. Polynomial models of the data are generated and used to design the bearing prototype. The prototype was constructed and tested and shown to be stable. Further testing shows the possibility of using this technology for vibration isolation. The project successfully demonstrated the viability of the passive magnetic bearing with ferrofluid stabilization both experimentally and analytically.

  16. Cryogenic, high speed, turbopump bearing cooling requirements

    NASA Technical Reports Server (NTRS)

    Dolan, Fred J.; Gibson, Howard G.; Cannon, James L.; Cody, Joe C.

    1988-01-01

    Although the Space Shuttle Main Engine (SSME) has repeatedly demonstrated the capability to perform during launch, the High Pressure Oxidizer Turbopump (HPOTP) main shaft bearings have not met their 7.5 hour life requirement. A tester is being employed to provide the capability of subjecting full scale bearings and seals to speeds, loads, propellants, temperatures, and pressures which simulate engine operating conditions. The tester design permits much more elaborate instrumentation and diagnostics than could be accommodated in an SSME turbopump. Tests were made to demonstrate the facilities; and the devices' capabilities, to verify the instruments in its operating environment and to establish a performance baseline for the flight type SSME HPOTP Turbine Bearing design. Bearing performance data from tests are being utilized to generate: (1) a high speed, cryogenic turbopump bearing computer mechanical model, and (2) a much improved, very detailed thermal model to better understand bearing internal operating conditions. Parametric tests were also made to determine the effects of speed, axial loads, coolant flow rate, and surface finish degradation on bearing performance.

  17. Genetic control of biennial bearing in apple

    PubMed Central

    Guitton, Baptiste; Kelner, Jean-Jacques; Velasco, Riccardo; Gardiner, Susan E.; Chagné, David; Costes, Evelyne

    2012-01-01

    Although flowering in mature fruit trees is recurrent, floral induction can be strongly inhibited by concurrent fruiting, leading to a pattern of irregular fruiting across consecutive years referred to as biennial bearing. The genetic determinants of biennial bearing in apple were investigated using the 114 flowering individuals from an F1 population of 122 genotypes, from a ‘Starkrimson’ (strong biennial bearer)בGranny Smith’ (regular bearer) cross. The number of inflorescences, and the number and the mass of harvested fruit were recorded over 6 years and used to calculate 26 variables and indices quantifying yield, precocity of production, and biennial bearing. Inflorescence traits exhibited the highest genotypic effect, and three quantitative trait loci (QTLs) on linkage group (LG) 4, LG8, and LG10 explained 50% of the phenotypic variability for biennial bearing. Apple orthologues of flowering and hormone-related genes were retrieved from the whole-genome assembly of ‘Golden Delicious’ and their position was compared with QTLs. Four main genomic regions that contain floral integrator genes, meristem identity genes, and gibberellin oxidase genes co-located with QTLs. The results indicated that flowering genes are less likely to be responsible for biennial bearing than hormone-related genes. New hypotheses for the control of biennial bearing emerged from QTL and candidate gene co-locations and suggest the involvement of different physiological processes such as the regulation of flowering genes by hormones. The correlation between tree architecture and biennial bearing is also discussed. PMID:21963613

  18. Development of a high speed parallel hybrid boost bearing

    NASA Technical Reports Server (NTRS)

    Winn, L. W.; Eusepi, M. W.

    1973-01-01

    The analysis, design, and testing of the hybrid boost bearing are discussed. The hybrid boost bearing consists of a fluid film bearing coupled in parallel with a rolling element bearing. This coupling arrangement makes use of the inherent advantages of both the fluid film and rolling element bearing and at the same time minimizes their disadvantages and limitations. The analytical optimization studies that lead to the final fluid film bearing design are reported. The bearing consisted of a centrifugally-pressurized planar fluid film thrust bearing with oil feed through the shaft center. An analysis of the test ball bearing is also presented. The experimental determination of the hybrid bearing characteristics obtained on the basis of individual bearing component tests and a combined hybrid bearing assembly is discussed and compared to the analytically determined performance characteristics.

  19. Design of gas bearing systems for precision applications

    NASA Astrophysics Data System (ADS)

    Wang, Junming

    Research to provide the up to date knowledge and efficient tools to design better Externally Pressurized Gas (EPG) bearing systems, including the design of individual bearings, and to arrange all the bearings used in an optimal way is reported. Both circular and rectangular EPG pads with rigid bearing surfaces and rigid inlet restrictors were used. The following topics closely related to the applications in precision engineering are discussed: influences of gap shape on the bearing performance; effects of bearing body tilt on the bearing performance; influences of bearing surface imperfections on bearing performance; temperature drops in EPG bearings in quasistationary conditions; the optimal use of multiple bearings in a mechanical system; the use of EPG bearing damping characteristics in the design; and the effects of motion velocity.

  20. Future Bearing Surfaces in Total Hip Arthroplasty

    PubMed Central

    2014-01-01

    One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Extensive research on bearing surfaces is being conducted to seek an ideal bearing surface for THA. The ideal bearing surface for THA should have superior wear characteristics and should be durable, bio-inert, cost-effective, and easy to implant. However, bearing surfaces that are currently being implemented do not completely fulfill these requirements, especially for young individuals for whom implant longevity is paramount. Even though various new bearing surfaces have been investigated, research is still ongoing, and only short-term results have been reported from clinical trials. Future bearing surfaces can be developed in the following ways: (1) change in design, (2) further improvement of polyethylene, (3) surface modification of the metal, (4) improvement in the ceramic, and (5) use of alternative, new materials. One way to reduce wear and impingement in THA is to make changes in its design by using a large femoral head, a monobloc metal shell with preassembled ceramic liner, dual mobility cups, a combination of different bearing surfaces, etc. Polyethylene has improved over time with the development of highly crosslinked polyethylene. Further improvements can be made by reinforcing it with vitamin E or multiwalled carbon nanotubes and by performing a surface modification with a biomembrane. Surface modifications with titanium nitride or titanium niobium nitride are implemented to try to improve the metal bearings. The advance to the fourth generation ceramics has shown relatively promising results, even in young patients. Nevertheless, further improvement is required to reduce fragility and squeaking. Alternative materials like diamond coatings on surfaces, carbon based composite materials, oxidized zirconium, silicon nitride, and sapphire are being sought. However, long-term studies are necessary to confirm the efficacy of these surfaces after enhancements

  1. Future bearing surfaces in total hip arthroplasty.

    PubMed

    Chang, Jun-Dong

    2014-03-01

    One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Extensive research on bearing surfaces is being conducted to seek an ideal bearing surface for THA. The ideal bearing surface for THA should have superior wear characteristics and should be durable, bio-inert, cost-effective, and easy to implant. However, bearing surfaces that are currently being implemented do not completely fulfill these requirements, especially for young individuals for whom implant longevity is paramount. Even though various new bearing surfaces have been investigated, research is still ongoing, and only short-term results have been reported from clinical trials. Future bearing surfaces can be developed in the following ways: (1) change in design, (2) further improvement of polyethylene, (3) surface modification of the metal, (4) improvement in the ceramic, and (5) use of alternative, new materials. One way to reduce wear and impingement in THA is to make changes in its design by using a large femoral head, a monobloc metal shell with preassembled ceramic liner, dual mobility cups, a combination of different bearing surfaces, etc. Polyethylene has improved over time with the development of highly crosslinked polyethylene. Further improvements can be made by reinforcing it with vitamin E or multiwalled carbon nanotubes and by performing a surface modification with a biomembrane. Surface modifications with titanium nitride or titanium niobium nitride are implemented to try to improve the metal bearings. The advance to the fourth generation ceramics has shown relatively promising results, even in young patients. Nevertheless, further improvement is required to reduce fragility and squeaking. Alternative materials like diamond coatings on surfaces, carbon based composite materials, oxidized zirconium, silicon nitride, and sapphire are being sought. However, long-term studies are necessary to confirm the efficacy of these surfaces after enhancements

  2. Titanium carbide coatings for aerospace ball bearings

    NASA Technical Reports Server (NTRS)

    Boving, Hans J.; Haenni, Werner; Hintermann, HANS-E.

    1988-01-01

    In conventional ball bearings, steel to steel contacts between the balls and the raceways are at the origin of microwelds which lead to material transfer, surface roughening, lubricant breakdown, and finally to a loss in the bearing performances. To minimize the microwelding tendencies of the contacting partners it is necessary to modify their surface materials; the solid to solid collisions themselves are difficult to avoid. The use of titanium carbide coated steel balls can bring spectacular improvements in the performances and lifetimes of both oil-grease lubricated and oil-grease free bearings in a series of severe applications.

  3. Microeconomic analysis of military aircraft bearing restoration

    NASA Technical Reports Server (NTRS)

    Hein, G. F.

    1976-01-01

    The risk and cost of a bearing restoration by grinding program was analyzed. A microeconomic impact analysis was performed. The annual cost savings to U.S. Army aviation is approximately $950,000.00 for three engines and three transmissions. The capital value over an indefinite life is approximately ten million dollars. The annual cost savings for U.S. Air Force engines is approximately $313,000.00 with a capital value of approximately 3.1 million dollars. The program will result in the government obtaining bearings at lower costs at equivalent reliability. The bearing industry can recover lost profits during a period of reduced demand and higher costs.

  4. Quantifying oil filtration effects on bearing life

    NASA Technical Reports Server (NTRS)

    Needelman, William M.; Zaretsky, Erwin V.

    1991-01-01

    Rolling-element bearing life is influenced by the number, size, and material properties of particles entering the Hertzian contact of the rolling element and raceway. In general, rolling-element bearing life increases with increasing level of oil filtration. Based upon test results, two equations are presented which allow for the adjustment of bearing L(sub 10) or catalog life based upon oil filter rating. It is recommended that where no oil filtration is used catalog life be reduced by 50 percent.

  5. Compressor ported shroud for foil bearing cooling

    DOEpatents

    Elpern, David G.; McCabe, Niall; Gee, Mark

    2011-08-02

    A compressor ported shroud takes compressed air from the shroud of the compressor before it is completely compressed and delivers it to foil bearings. The compressed air has a lower pressure and temperature than compressed outlet air. The lower temperature of the air means that less air needs to be bled off from the compressor to cool the foil bearings. This increases the overall system efficiency due to the reduced mass flow requirements of the lower temperature air. By taking the air at a lower pressure, less work is lost compressing the bearing cooling air.

  6. Noninvasive methods for monitoring bear population trends

    USGS Publications Warehouse

    Kendall, Katherine

    2010-01-01

    The U.S. Geological Survey began a grizzly bear research project in 2009 in the Northern Continental Divide Ecosystem (NCDE) of northwestern Montana. This work uses hair collection and DNA analysis methods similar to those used in the 2004 Northern Divide Grizzly Bear Project. However, instead of producing a snapshot of population size, the objectives of this new work are to estimate population growth rates by collecting hair at natural bear rubs along trails, roads, and fence and power lines. This approach holds promise of providing reliable estimates of population trends in an efficient, cost-effective, and unobtrusive way.

  7. Active magnetic bearings applied to industrial compressors

    NASA Technical Reports Server (NTRS)

    Kirk, R. G.; Hustak, J. F.; Schoeneck, K. A.

    1993-01-01

    The design and shop test results are given for a high-speed eight-stage centrifugal compressor supported by active magnetic bearings. A brief summary of the basic operation of active magnetic bearings and the required rotor dynamics analysis are presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofits of magnetic bearings in existing machinery are discussed with supporting analysis of a four-stage centrifugal compressor. The current status of industrial machinery in North America using this new support system is presented and recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

  8. Conical Magnetic Bearing Development and Magnetic Bearing Testing for Extreme Temperature Environments

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Jansen, Mark

    2004-01-01

    The main proposed research of this grant were: to design a high-temperature, conical magnetic bearing facility, to test the high-temperature, radial magnetic bearing facility to higher speeds, to investigate different backup bearing designs and materials, to retrofit the high-temperature test facility with a magnetic thrust bearing, to evaluate test bearings at various conditions, and test several lubricants using a spiral orbit tribometer. A high-temperature, conical magnetic bearing facility has been fully developed using Solidworks. The facility can reuse many of the parts of the current high-temperature, radial magnetic bearing, helping to reduce overall build costs. The facility has the ability to measure bearing force capacity in the X, Y, and Z directions through a novel bearing mounting design. The high temperature coils and laminations, a main component of the facility, are based upon the current radial design and can be fabricated at Texas A&M University. The coil design was highly successful in the radial magnetic bearing. Vendors were contacted about fabrication of the high temperature lamination stack. Stress analysis was done on the laminations. Some of the components were procured, but due to budget cuts, the facility build up was stopped.

  9. Transient unbalance response of four multilobe journal bearings

    NASA Technical Reports Server (NTRS)

    Allaire, P. E.; Li, D. F.; Choy, K. C.

    1979-01-01

    This work carries out an analysis of the transient response of four multilobe journal bearings (elliptical, offset, three-lobe, and four-lobe) subject to unbalance both below and above the linearized stability thresholds for the bearings. It extends the work of a previous paper on a balanced rotor in the same four bearing types. Transient orbits, bearing forces, and a numerical fast Fourier transform analysis of the orbits are presented. A comparison of bearing forces above the stability threshold for each bearing indicates that the elliptical bearing has the most violent whirl vibration amplitudes, while the offset bearing exhibits the least amount of subsynchronous vibration.

  10. Molecular phylogeny and SNP variation of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) derived from genome sequences.

    PubMed

    Cronin, Matthew A; Rincon, Gonzalo; Meredith, Robert W; MacNeil, Michael D; Islas-Trejo, Alma; Cánovas, Angela; Medrano, Juan F

    2014-01-01

    We assessed the relationships of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) with high throughput genomic sequencing data with an average coverage of 25× for each species. A total of 1.4 billion 100-bp paired-end reads were assembled using the polar bear and annotated giant panda (Ailuropoda melanoleuca) genome sequences as references. We identified 13.8 million single nucleotide polymorphisms (SNP) in the 3 species aligned to the polar bear genome. These data indicate that polar bears and brown bears share more SNP with each other than either does with black bears. Concatenation and coalescence-based analysis of consensus sequences of approximately 1 million base pairs of ultraconserved elements in the nuclear genome resulted in a phylogeny with black bears as the sister group to brown and polar bears, and all brown bears are in a separate clade from polar bears. Genotypes for 162 SNP loci of 336 bears from Alaska and Montana showed that the species are genetically differentiated and there is geographic population structure of brown and black bears but not polar bears. PMID:24477675

  11. 30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND LOWER CHORD DETAIL OF DECK TRUSS. VIEW TO NORTHEAST. - Abraham Lincoln Memorial Bridge, Spanning Missouri River on Highway 30 between Nebraska & Iowa, Blair, Washington County, NE

  12. Novel nano bearings constructed by physical adsorption

    PubMed Central

    Zhang, Yongbin

    2015-01-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film. PMID:26412488

  13. Remote lubrication system for conveyor bearing

    SciTech Connect

    Bandy, C.L. Jr.

    1993-08-03

    In an assembly having a hard-to-reach rotary means supported by a bearing to be lubricated, a housing enclosing said bearing, and a fixed frame means for mounting said rotary means through said housing, a lubrication system is described comprising: access ports in said housing for communicating lubricant to said bearing; an elongated channel of predetermined length having at least two ends in said fixed frame means in fluid communication with at least one of said access ports located between said ends; means for sealing the ports not aligned with said channel; and stationary conduit means leading to a remote location in fluid communication with said channel; whereby lubricant is communicated through said conduit means, said channel, and at least one of said access ports for application to said bearing from a remote location.

  14. Novel nano bearings constructed by physical adsorption.

    PubMed

    Zhang, Yongbin

    2015-01-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film. PMID:26412488

  15. Gauge Measures Large Spherical Bearing Surfaces

    NASA Technical Reports Server (NTRS)

    Davis, George L.

    1992-01-01

    Radius of spherical portion of surface computed from reading of depth gauge. Measuring tool calibrated by applying it to reference spherical surface of known radius. Used onsite, so unnecessary to ship bearings to laboratory for examination by computerized test equipment.

  16. Microfog lubrication for aircraft engine bearings

    NASA Technical Reports Server (NTRS)

    Rosenlieb, J. W.

    1976-01-01

    An analysis and system study was performed to provide design information regarding lubricant and coolant flow rates and flow paths for effective utilization of the lubricant and coolant in a once through bearing oil mist (microfog) and coolant air system. Both static and dynamic tests were performed. Static tests were executed to evaluate and calibrate the mist supply system. A total of thirteen dynamic step speed bearing tests were performed using four different lubricants and several different mist and air supply configurations. The most effective configuration consisted of supplying the mist and the major portion of the cooling air axially through the bearing. The results of these tests have shown the feasibility of using a once through oil mist and cooling air system to lubricate and cool a high speed, high temperature aircraft engine mainshaft bearing.

  17. Novel nano bearings constructed by physical adsorption

    NASA Astrophysics Data System (ADS)

    Zhang, Yongbin

    2015-09-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film.

  18. Magnetic bearings: Fifty years of progress

    NASA Technical Reports Server (NTRS)

    Swann, Michael K.

    1993-01-01

    Magnetic bearings are just beginning to be flown in spacecraft systems, but their development spans more than 50 years. The promise of completely noncontacting, unlubricated rotating systems operating at speeds substantially beyond the range of conventional bearings, and with no wear and virtually no vibration, has provided the incentive to develop magnetic bearing technology for many diverse applications. Earnshaw theorized in 1842 that stable magnetic suspension is not possible in all three spatial directions unless the magnetic field is actively controlled. Since that time, researchers have attempted to successfully support spinning rotors in a stable manner. Development of magnetic suspension systems over the past fifty years has included progress on both passive (permanent magnet) and active (electromagnet) systems. The improvements in bearing load capacity, stiffness, and damping characteristics are traced. The trends in rotor size, rotational kinetic energy, and improvements in active control systems capabilities are also reviewed. Implications of superconductivity on suspension system design and performance are discussed.

  19. Active Control of Magnetically Levitated Bearings

    SciTech Connect

    BARNEY, PATRICK S.; LAUFFER, JAMES P.; REDMOND, JAMES M.; SULLIVAN, WILLIAM N.

    2001-03-01

    This report summarizes experimental and test results from a two year LDRD project entitled Real Time Error Correction Using Electromagnetic Bearing Spindles. This project was designed to explore various control schemes for levitating magnetic bearings with the goal of obtaining high precision location of the spindle and exceptionally high rotational speeds. As part of this work, several adaptive control schemes were devised, analyzed, and implemented on an experimental magnetic bearing system. Measured results, which indicated precision positional control of the spindle was possible, agreed reasonably well with simulations. Testing also indicated that the magnetic bearing systems were capable of very high rotational speeds but were still not immune to traditional structural dynamic limitations caused by spindle flexibility effects.

  20. Rolling-Contact Spalling In Bearings

    NASA Technical Reports Server (NTRS)

    Kumar, A. M.; Kulkarni, S. M.; Bhargava, B.; Hahn, G. T.; Rubin, C. A.

    1990-01-01

    Report describes experimental and theoretical studies of effects of thermal and mechanical contact stresses and attendant plastic deformations responsible for rolling-contact spalling of the 440C-steel bearings in high-pressure-oxygen turbopump.

  1. Effect of Surface Roughness on Hydrodynamic Bearings

    NASA Technical Reports Server (NTRS)

    Majumdar, B. C.; Hamrock, B. J.

    1981-01-01

    A theoretical analysis on the performance of hydrodynamic oil bearings is made considering surface roughness effect. The hydrodynamic as well as asperity contact load is found. The contact pressure was calculated with the assumption that the surface height distribution was Gaussian. The average Reynolds equation of partially lubricated surface was used to calculate hydrodynamic load. An analytical expression for average gap was found and was introduced to modify the average Reynolds equation. The resulting boundary value problem was then solved numerically by finite difference methods using the method of successive over relaxation. The pressure distribution and hydrodynamic load capacity of plane slider and journal bearings were calculated for various design data. The effects of attitude and roughness of surface on the bearing performance were shown. The results are compared with similar available solution of rough surface bearings. It is shown that: (1) the contribution of contact load is not significant; and (2) the hydrodynamic and contact load increase with surface roughness.

  2. AX-5 space suit bearing torque investigation

    NASA Technical Reports Server (NTRS)

    Loewenthal, Stuart; Vykukal, Vic; Mackendrick, Robert; Culbertson, Philip, Jr.

    1990-01-01

    The symptoms and eventual resolution of a torque increase problem occurring with ball bearings in the joints of the AX-5 space suit are described. Starting torques that rose 5 to 10 times initial levels were observed in crew evaluation tests of the suit in a zero-g water tank. This bearing problem was identified as a blocking torque anomaly, observed previously in oscillatory gimbal bearings. A large matrix of lubricants, ball separator designs and materials were evaluated. None of these combinations showed sufficient tolerance to lubricant washout when repeatedly cycled in water. The problem was resolved by retrofitting a pressure compensated, water exclusion seal to the outboard side of the bearing cavity. The symptoms and possible remedies to blocking are discussed.

  3. Alternative bearing surfaces in total hip arthroplasty.

    PubMed

    Inzerillo, V Christopher; Garino, Jonathan P

    2003-01-01

    Polyethylene wear and extension of indications of total hip arthroplasty into younger and younger age groups have pushed manufacturers to develop more durable bearing surfaces. Standard polyethylene, the plastic used for the first 3 decades of hip replacement, virtually ceases to exist in its original form. Modifications of the processing, including sterlization in an inert environment and cross-linking, have demonstrated some improvements in wear. Hard-on-hard bearings such as ceramic-on-ceramic and metal-on-metal also have demonstrated extremely low wear. This article reviews the pros and cons of the alternative bearing options available to assist in the proper bearing selection for a particular patient. PMID:12882250

  4. Mini-BRU/BIPS foil bearing development

    NASA Technical Reports Server (NTRS)

    Dobler, F. X.; Miller, L. J.

    1978-01-01

    The analysis revealed the failure agent to be a combination of poor teflon coating adhesion, a decrease in bearing sway space and, possibly, lack of flushing flow through the bearing. A change in Teflon coating vendors provided substantially improved coating quality and surface finish. The sway space was increased and the cooling bleed flow was adjusted to flush the bearing. These changes were included in a test conducted in the WHL from 6 April to 22 May 1978 which resulted in the completion of 1006.9 hours of operation at temperature and load. Post-test inspection revealed the bearings to be in excellent condition and capable of completing a much longer test.

  5. Ceramic Rail-Race Ball Bearings

    NASA Technical Reports Server (NTRS)

    Balzer, Mark A.; Mungas, Greg S.; Peters, Gregory H.

    2010-01-01

    Non-lubricated ball bearings featuring rail races have been proposed for use in mechanisms that are required to function in the presence of mineral dust particles in very low-pressure, dry environments with extended life. Like a conventional ball bearing, the proposed bearing would include an inner and an outer ring separated by balls in rolling contact with the races. However, unlike a conventional ball bearing, the balls would not roll in semi-circular or gothic arch race grooves in the rings: instead, the races would be shaped to form two or more rails (see figure). During operation, the motion of the balls would push dust particles into the spaces between the rails where the particles could not generate rolling resistance for the balls

  6. Life analysis of restored and refurbished bearings

    NASA Technical Reports Server (NTRS)

    Coy, J. J.; Zaretsky, E. V.; Cowgill, G. R.

    1977-01-01

    An analysis of the potential life of refurbished and restored bearings was performed. The sensitivity of 10-percent life and mean-time-between-failure to the effects of cumulative fatigue damage and the amount of stressed volume removed in the restoration process were examined. A modified Lundberg-Palmgren theory was used to predict that the expected 10-percent life of a restored bearing, which is dependent on the previous service time and the volume of material removed from the race surfaces, can be between 74 and 100 percent of the new bearing life. Using renewal theory, it is found that the mean time between failure ranged from 90 to 100 percent of that for a new bearing.

  7. Mercury biomagnification in polar bears ( Ursus maritimus)

    NASA Astrophysics Data System (ADS)

    Horton, T. W.; Blum, J. D.; Xie, Z.; Hren, M.; Chamberlain, C. P.

    2007-12-01

    Mercury biomagnification occurs in a variety of ecosystems resulting in greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different foodweb channels are not well known, particularly in high-latitude systems affected by atmospheric Hg deposition associated with snow and ice. Stable carbon and nitrogen isotope ratios and Hg concentrations determined for 26 late 19th and early 20th century polar bear hair specimens collected from cataloged museum collections elucidate relationships between high latitude marine foodweb structure and Hg transport pathways. Nitrogen and carbon isotopic compositions suggest that polar bears derive nutrition from both open water (pelagic) and ice associated (sympagic) foodweb channels. Correlation between Hg concentrations and nitrogen isotope compositions indicate mercury biomagnification occurred in most of the polar bears investigated. Interpretation of stable isotope based foodweb structure in concert with Hg concentrations further suggests that Hg biomagnification occurred to a greater degree in polar bears participating in pelagic foodweb channels.

  8. RUBBER BEARINGS FOR DOWN-HOLE PUMPS

    SciTech Connect

    Bob Sullivan Mammoth Pacific, L.P.

    2005-09-07

    Synopsis of project activity: 1998--Awarded cost share grant from DOE. 1st Qtr 1999--Developed fail safe lubricating system. 2nd Qtr 1999--Performed first large scale test with nitrile based bearings. It failed due to material swelling. Failure was blamed on improper tolerance. 3rd Qtr 1999--Material tests were performed with autoclaves and exposure tests to Casa Diablo fluids. Testing of Viton materials began. Alternate bearing designs were developed to limit risk of improper tolerances. 4th Qtr 1999--Site testing indicated a chemical attack on the bearing material caused the test failure and not improper bearing tolerance. 1st Qtr 2000--The assistance of Brookhaven National Laboratory was obtained in evaluating the chemical attack. The National Laboratory also began more elaborate laboratory testing on bearing materials. 2nd Qtr 2000--Testing indicated Viton was an inappropriate material due to degradation in Casa Diablo fluid. Testing of EPDM began. 3rd Qtr 2001--EPDM bearings were installed for another large scale test. Bearings failed again due to swelling. Further testing indicated that larger then expected oil concentrations existed in lubricating water geothermal fluid causing bearing failure. 2002-2003--Searched for and tested several materials that would survive in hot salt and oil solutions. Kalrez{reg_sign}, Viton{reg_sign}ETP 500 and Viton{reg_sign}GF were identified as possible candidates. 2003-2005--Kalrez{reg_sign}has shown superior resistance to downhole conditions at Casa Diablo from among the various materials tested. Viton ETP-500 indicated a life expectancy of 13 years and because it is significantly less expensive then Kalrez{reg_sign}, it was selected as the bearing material for future testing. Unfortunately during the laboratory testing period Dupont Chemical chose to stop manufacturing this specific formulation and replaced it with Viton ETP 600S. The material is available with six different fillers; three based on zinc oxide and three

  9. Active magnetic bearings used as exciters for rolling element bearing outer race defect diagnosis.

    PubMed

    Xu, Yuanping; Di, Long; Zhou, Jin; Jin, Chaowu; Guo, Qintao

    2016-03-01

    The active health monitoring of rotordynamic systems in the presence of bearing outer race defect is considered in this paper. The shaft is assumed to be supported by conventional mechanical bearings and an active magnetic bearing (AMB) is used in the mid of the shaft location as an exciter to apply electromagnetic force to the system. We investigate a nonlinear bearing-pedestal system model with the outer race defect under the electromagnetic force. The nonlinear differential equations are integrated using the fourth-order Runge-Kutta algorithm. The simulation and experimental results show that the characteristic signal of outer race incipient defect is significantly amplified under the electromagnetic force through the AMBs, which is helpful to improve the diagnosis accuracy of rolling element bearing׳s incipient outer race defect. PMID:26803551

  10. Genetic relationships of extant brown bears (Ursus arctos) and polar bears (Ursus maritimus).

    PubMed

    Cronin, Matthew A; MacNeil, Michael D

    2012-01-01

    Polar bears (Ursus maritimus) and brown bears (Ursus arctos) are closely related species for which extensive mitochondrial and nuclear phylogenetic comparisons have been made. We used previously published genotype data for 8 microsatellite DNA loci from 930 brown bears in 19 populations and 473 polar bears in 16 populations to compare the population genetic relationships of extant populations of the species. Genetic distances (Nei standard distance = 1.157), the proportion of private alleles (52% of alleles are not shared by the species), and Bayesian cluster analysis are consistent with morphological and life-history characteristics that distinguish polar bears and brown bears as different species with little or no gene flow among extant populations. PMID:23125409

  11. Spectral properties and identification of aerostatic bearings

    NASA Astrophysics Data System (ADS)

    Kozánek, Jan; Půst, Ladislav

    2011-02-01

    Modified rotor kit Bently Nevada was used for dynamic characteristics measurements of new developed aerostatic bearings. Mathematicalmodel of these bearings is considered as linear. Model was identified with the help of harmonic force excitation independently from the speed of journal rotation. The stiffness and damping matrices were identified for different air inlet pressures. The calculated spectral properties allow to determine the stability boundary for suitable variation of model parameters.

  12. Earth Scanner Bearing Accelerated Life Test

    NASA Technical Reports Server (NTRS)

    Dietz, Brian J.; VanDyk, Steven G.; Predmore, Roamer E.

    2000-01-01

    The Moderate Resolution Imaging Spectrometer (MODIS) optical instrument for NASA Goddard will measure biological and physical processes on the Earth's surface and in the lower atmosphere. A key component of the instrument is an extremely accurate scan mirror motor/encoder assembly. Of prime concern in the performance and reliability of the scan motor/encoder is bearing selection and lubrication. This paper describes life testing of the bearings and lubrication selected for the program.

  13. Bearing steels: Into the 21. century

    SciTech Connect

    Hoo, J.J.C.; Green, W.B. Jr.

    1998-12-31

    The symposium was organized in 9 separate categories, some sessions updating information previously presented, and some presenting brand new materials and processing to advance bearing technology. Subjects covered include steel cleanliness and measuring methods, bearing fatigue life, and advanced steel processing. Also covered are advances in both thru-hardening and carburizing heat treatments, progress in aerospace and corrosion resistant materials, and surface modifying processes, such as induction hardening and coating methods. Papers have been processed separately for inclusion on the data base.

  14. Passive magnetic bearings for vehicular electromechanical batteries

    SciTech Connect

    Post, R

    1996-03-01

    This report describes the design of a passive magnetic bearing system to be used in electromechanical batteries (flywheel energy storage modules) suitable for vehicular use. One or two such EMB modules might, for example, be employed in a hybrid-electric automobile, providing efficient means for power peaking, i.e., for handling acceleration and regenerative braking power demands at high power levels. The bearing design described herein will be based on a ''dual-mode'' operating regime.

  15. Active magnetic bearings for optimum turbomachinery design

    NASA Technical Reports Server (NTRS)

    Hustak, J.; Kirk, R. G.; Schoeneck, K. A.

    1985-01-01

    The design and shop test results are given for a high speed eight stage centrifugal compressor supported by active magnetic bearings. A brief summary of the rotor dynamics analysis is presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofit of magnetic bearings in existing machinery are discussed with supporting analysis of a four stage centrifugal compressor. Recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

  16. Flywheel energy storage with superconductor magnetic bearings

    DOEpatents

    Weinberger, Bernard R.; Lynds, Jr., Lahmer; Hull, John R.

    1993-01-01

    A flywheel having superconductor bearings has a lower drag to lift ratio that translates to an improvement of a factor of ten in the rotational decay rate. The lower drag results from the lower dissipation of melt-processed YBCO, improved uniformity of the permanent magnet portion of the bearings, operation in a different range of vacuum pressure from that taught by the art, and greater separation distance from the rotating members of conductive materials.

  17. Monitoring Bearing Vibrations For Signs Of Damage

    NASA Technical Reports Server (NTRS)

    Martinez, Carol L.

    1991-01-01

    Real-time spectral analysis of vibrations being developed for use in monitoring conditions of critical bearings in rotating machinery. Underlying concept simple and fairly well established: appearance and growth of vibrations at frequencies associated with rotations of various parts of bearing system indicate wear, damage, and imperfections of manufacture. Frequencies include fundamental and harmonics of frequency of rotation of ball cage, frequency of passage of balls, and frequency of rotation of shaft.

  18. Dynamic tester for rotor seals and bearings

    NASA Technical Reports Server (NTRS)

    Vonpragenau, George L. (Inventor)

    1993-01-01

    A dynamic tester for testing vibration damping seals and bearings is constructed having a hollow shaft extending through the seal or bearing, with the shaft internally supported at each end by fluid bearings on hollow bosses connected to an interior of an enclosure, with no rolling members connected to the shaft is described. A high pressure working fluid is forced through the hollow bosses to operate the bearings. Additionally, the shaft is provided with a reaction turbine that angularly vents a portion of the high pressure working fluid in order to rotate the shaft at high speed, up to 40,000 rpm. The seal or bearing is mounted in a bushing, in turn supported by rods to a shaking device that vibrates the seal or bearing as the shaft is rotated. A plurality of proximity sensors are mounted from outside the enclosure to sense shaft and seal bushing vibrations, and a plurality of pressure ports are disposed in the enclosure to allow sensing of dynamic and static pressures of the testing apparatus.

  19. Bearing and gear steels for aerospace applications

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1990-01-01

    Research in metallurgy and processing for bearing and gear steels has resulted in improvements in rolling-element bearing and gear life for aerospace application by a factor of approximately 200 over that obtained in the early 1940's. The selection and specification of a bearing or gear steel is dependent on the integration of multiple metallurgical and physical variables. For most aerospace bearings, through-hardened VIM-VAR AISI M-50 steel is the material of preference. For gears, the preferential material is case-carburized VAR AISI 9310. However, the VAR processing for this material is being replaced by VIM-VAR processing. Since case-carburized VIM-VAR M-50NiL incorporates the desirable qualities of both the AISI M-50 and AISI 9310 materials, optimal life and reliability can be achieved in both bearings and gears with a single steel. Hence, this material offers the promise of a common steel for both bearings and gears for future aerospace applications.

  20. Rotordynamics and bearing design of turbochargers

    NASA Astrophysics Data System (ADS)

    Chen, Wen Jeng

    2012-05-01

    Turbochargers have gained significant attention in recent years. They are already widely used in automotive, locomotive, and marine applications with diesel engines. They are also applied in the aerospace application to increase the engine performance now. The turbochargers used in automotive and aerospace industry are very light-weight with operating speeds above 100,000 rpm. The turbochargers used in locomotive and marine applications are relatively heavy in size and power compared to the automotive and aerospace applications, and the maximum continuous operating speeds are around 30,000 rpm depending on the diesel engine power rating. Floating ring bushings, semi-floating dampers, ball bearings, and ball bearings with dampers are commonly used in automotive applications for small turbochargers. However, these bearings may not be appropriate for large turbochargers in locomotive and marine applications. Instead, multi-lobed bearings with and without squeeze film dampers are commonly used in these heavy-duty turbochargers. This paper deals with the rotordynamic characteristics of larger turbochargers in locomotive and marine applications. Various bearing designs are discussed. Bearing design parameters are studied and optimal values are suggested. Test results are also presented to support the analytical simulation.

  1. Adaptive Spindle Balancing Using Magnetically Levitated Bearings

    SciTech Connect

    BARNEY,PATRICK S.; LAUFFER,JAMES P.; PETTEYS,REBECCA; REDMOND,JAMES M.; SULLIVAN,WILLIAM N.

    1999-09-20

    A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings offer some important advantages over conventional ball, roller or journal bearings such as reduced frictional drag, no physical contact in the bearing, no need for lubricants, compatibility with high vacuum and ultra-clean environments, and ability to control shaft position within the bearing. The disadvantages of the AMB system are the increased cost and complexity, reduced bearing stiffness and the need for a controller. Still, there are certain applications, such as high speed machining, biomedical devices, and gyroscopes, where the additional cost of an AMB system can be justified. The inherent actuator capabilities of the AMB offer the potential for active balancing of spindles and micro-shaping capabilities for machine tools, The work presented in this paper concentrates on an AMB test program that utilizes the actuator capability to dynamically balance a spindle. In this study, an unbalanced AMB spindle system was enhanced with an LMS (Least Mean Squares) algorithm combined with an existing PID (proportional, integral, differential) control. This enhanced controller significantly improved the concentricity of an intentionally unbalanced shaft. The study included dynamic system analysis, test validation, control design and simulation, as well as experimental implementation using a digital LMS controller.

  2. Optimal speed sharing characteristics of a series-hybrid bearing

    NASA Technical Reports Server (NTRS)

    Nypan, L. J.; Scibbe, H. W.; Hamrock, B. J.

    1972-01-01

    A series-hybrid bearing assembly consisting of a conical hydrostatic fluid-film bearing and a ball bearing is described. Computer studies are used to predict friction torque and life characteristics of a 150-millimeter ball bearing. A conical hydrostatic fluid-film bearing is designed for minimum friction and maximum speed reduction of the ball-bearing component of the series-hydrid bearing. At a thrust load of 4000 pounds and speeds corresponding to DN (bearing bore in millimeters times shaft speed in rpm) values of 3 and 4 million, ball-bearing speed may be reduced by 30 percent. This speed reduction corresponds to ball-bearing fatigue life improvement factors of 3.4 at 3 million DN and 5.9 at 4 million DN. An oil flow rate of 18.2 pounds per minute is required to maintain a fluid-film thickness of 0.001 inch in the hydrostatic bearing.

  3. Optimal speed sharing characteristics of a series-hybrid bearing.

    NASA Technical Reports Server (NTRS)

    Nypan, L. J.; Scibbe, H. W.; Hamrock, B. J.

    1972-01-01

    A series-hybrid bearing assembly consisting of a conical hydrostatic fluid-film bearing and a ball bearing is described. Computer studies are used to predict friction torque and life characteristics of a 150-mm ball bearing. A conical hydrostatic fluid-film bearing is designed for minimum friction and maximum speed reduction of the ball-bearing component of the series-hybrid bearing. At a thrust load of 4000 lb and speeds corresponding to DN (bearing bore in millimeters times shaft speed in rpm) values of 3 and 4 million, ball-bearing speed may be reduced to 30%. This speed reduction corresponds to ball-bearing fatigue life improvement factors of 3.4 at 3 million DN and 5.9 at 4 million DN. An oil flow rate at 18.2 lb/min is required to maintain a fluid-film thickness of 0.001 in. in the hydrostatic bearing.

  4. Fault Tolerant Magnetic Bearing Testing and Conical Magnetic Bearing Development for Extreme Temperature Environments

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Clark, Daniel

    2004-01-01

    During the six month tenure of the grant, activities included continued research of hydrostatic bearings as a viable backup-bearing solution for a magnetically levitated shaft system in extreme temperature environments (1000 F), developmental upgrades of the fault-tolerant magnetic bearing rig at the NASA Glenn Research Center, and assisting in the development of a conical magnetic bearing for extreme temperature environments, particularly turbomachinery. It leveraged work from the ongoing Smart Efficient Components (SEC) and the Turbine-Based Combined Cycle (TBCC) program at NASA Glenn Research Center. The effort was useful in providing technology for more efficient and powerful gas turbine engines.

  5. Bearing Tester Data Compilation Analysis, and Reporting and Bearing Math Modeling

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The magnitude and direction of fluid induced torques and forces on the 57 mm bearing cage is considered to be a contributing factor in possible cage instabilities that can produce intermittent high heating in the bearing. Analyses of the fluid forces and torques are presented. Heat generated by viscous fluid work was estimated for two flow diverter configurations and a coolant flow of 10 lbs/sec to support the thermal evaluation of the LOX Bearing Materials Tester. Results of the analysis of the LOX turbopump turbine end bearings are discussed. Coolant velocities for the no. 4 LOX turbopump turbine end bearings were estimated as a function of shaft speed and coolant flow rate. Contact angles and track width data were developed for the 57 mm bearing as functions of shaft speed, and axial and radial loads. The Advanced Dynamics of Rolling Elements (ADORE) computer program was installed on the MSFC UNIVAC 1100 and a test case successfully run. Both the text output and the plotting output were verified. The Bearing Seal and Materials Tester - Test Condition Data Base was developed. The parametric analysis of the operating characteristics of the LOX turbopump pump end bearing using the 45 mm bearing thermal model was begun.

  6. Bears "Count" Too: Quantity Estimation and Comparison in Black Bears (Ursus Americanus).

    PubMed

    Vonk, Jennifer; Beran, Michael J

    2012-07-01

    Studies of bear cognition are notably missing from the comparative record despite bears' large relative brain size and interesting status as generalist carnivores facing complex foraging challenges, but lacking complex social structures. We investigated the numerical abilities of three American black bears (Ursus Americanus) by presenting discrimination tasks on a touch-screen computer. One bear chose the larger of two arrays of dot stimuli, while two bears chose the smaller array of dots. On some trials the relative number of dots was congruent with the relative total area of the two arrays. On other trials number of dots was incongruent with area. All of the bears were above chance on trials of both types with static dots. Despite encountering greater difficulty with dots that moved within the arrays, one bear was able to discriminate numerically larger arrays of moving dots, and a subset of moving dots from within the larger array, even when area and number were incongruent. Thus, although the bears used area as a cue to guide responding, they were also able to use number as a cue. The pattern of performance was similar to that found previously with monkeys, and suggests that bears may also show other forms of sophisticated quantitative abilities. PMID:22822244

  7. Analysis of ITT scan bearing package (bearing package S/N 7-1004)

    NASA Technical Reports Server (NTRS)

    Gelotte, Erik; Kauppinen, John

    1991-01-01

    A geostationary operational environments satellite (GOES) East-West scan-bearing assembly was examined after having completed two and one-half years of operation. The following results were found: (1) lubrication breakdown was found in both bearings; (2) patchy wear-bands running only approximately half-way around the races indicated a load distribution in the ball groups consistent with a very low preload; (3) contact angles of 31.2 deg (S/N 1004) and 28.7 deg (S/N 1004A) were found in bearings whose contact angles are supposed to be 20+/-2 deg; and (4) contamination was present in the bearings.

  8. A Wide Bandwidth Model for the Electrical Impedance of Magnetic BearingS

    NASA Technical Reports Server (NTRS)

    Meeker, David C.; Maslen, Eric H.; Noh, Myounggyu D.

    1996-01-01

    Magnetic bearings are often designed using magnetic circuit theory. When these bearings are built, however, effects not included in the usual circuit theory formulation have a significant influence on bearing performance. Two significant sources of error in the circuit theory approach are the neglect of leakage and fringing effects and the neglect of eddy current effects. This work formulates an augmented circuit model in which eddy current and flux leakage and fringing effects are included. Through the use of this model, eddy current power losses and actuator bandwidth can be derived. Electrical impedance predictions from the model are found to be in good agreement with experimental data from a typical magnetic bearing.

  9. Transient Vibration Prediction for Rotors on Ball Bearings Using Load-dependent Non-linear Bearing Stiffness

    NASA Technical Reports Server (NTRS)

    Fleming, David P.; Poplawski, J. V.

    2002-01-01

    Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic transient analysis requires bearing forces to be determined at each step of the transient solution. Analyses have been carried out to show the effect of accurate bearing transient forces (accounting for non-linear speed and load dependent bearing stiffness) as compared to conventional use of average rolling-element bearing stiffness. Bearing forces were calculated by COBRA-AHS (Computer Optimized Ball and Roller Bearing Analysis - Advanced High Speed) and supplied to the rotordynamics code ARDS (Analysis of Rotor Dynamic Systems) for accurate simulation of rotor transient behavior. COBRA-AHS is a fast-running 5 degree-of-freedom computer code able to calculate high speed rolling-element bearing load-displacement data for radial and angular contact ball bearings and also for cylindrical and tapered roller beatings. Results show that use of nonlinear bearing characteristics is essential for accurate prediction of rotordynamic behavior.

  10. Polar bears: the fate of an icon.

    PubMed

    Fitzgerald, Kevin T

    2013-11-01

    Polar bears are one of the most iconic animals on our planet. Worldwide, even people who would never see one are drawn to these charismatic arctic ice hunters. They are the world's largest terrestrial carnivore, and despite being born on land, they spend most of their lives out on the sea ice and are considered a marine mammal. Current global studies estimate there are around 20,000 animals in some 19 discrete circumpolar populations. Aside from pregnant females denning in the winter months to give birth, the white bears do not hibernate. They spend their winters on the sea ice hunting seals, an activity they are spectacularly adapted for. Research on these animals is incredibly difficult because of the inhospitable surroundings they inhabit and how inaccessible they make the bears. For many years, the sum of our understanding of the natural history of polar bears came from tracks, scats, the remains of their kills, abandoned dens, and anecdotal observations of native hunters, explorers, and early biologists. Nonetheless, the last 40 years have seen a much better picture of their biology emerge thanks to, first, dedicated Canadian researchers and, later, truly international efforts of workers from many countries. Veterinarians have contributed to our knowledge of the bears by delivering and monitoring anesthesia, obtaining blood samples, performing necropsies, investigating their reproduction, conducting radiotelemetry studies, and examining their behavior. Recently, new technologies have been developed that revolutionize the study of the lives and natural history of undisturbed polar bears. These advances include better satellite radiotelemetry equipment and the development of remote-controlled miniature devices equipped with high-definition cameras. Such new modalities provide dramatic new insights into the life of polar bears. The remarkable degree of specialized adaptation to life on the sea ice that allowed the bears to be successful is the very reason that

  11. Wave Journal Bearing. Part 2: Experimental Pressure Measurements and Fractional Frequency Whirl Threshold for Wave and Plain Journal Bearings

    NASA Technical Reports Server (NTRS)

    Walker, James F.; Dimofte, Florin; Addy, Harold E., Jr.

    1995-01-01

    A new hydrodynamic bearing concept, the wave journal bearing, is being developed because it has better stability characteristics than plain journal bearings while maintaining similar load capacity. An analysis code to predict the steady state and dynamic performance of the wave journal bearing is also part of the development. To verify numerical predictions and contrast the wave journal bearing's stability characteristics to a plain journal bearing, tests were conducted at NASA Lewis Research Center using an air bearing test rig. Bearing film pressures were measured at 16 ports located around the bearing circumference at the middle of the bearing length. The pressure measurements for both a plain journal bearing and a wave journal bearing compared favorably with numerical predictions. Both bearings were tested with no radial load to determine the speed threshold for self-excited fractional frequency whirl. The plain journal bearing started to whirl immediately upon shaft start-up. The wave journal did not incur self-excited whirl until 800 to 900 rpm as predicted by the analysis. Furthermore, the wave bearing's geometry limited the whirl orbit to less than the bearing's clearance. In contrast, the plain journal bearing did not limit the whirl orbit, causing it to rub.

  12. Polar bears in a warming climate.

    PubMed

    Derocher, Andrew E; Lunn, Nicholas J; Stirling, Ian

    2004-04-01

    Polar bears (Ursus maritimus) live throughout the ice-covered waters of the circumpolar Arctic, particularly in near shore annual ice over the continental shelf where biological productivity is highest. However, to a large degree under scenarios predicted by climate change models, these preferred sea ice habitats will be substantially altered. Spatial and temporal sea ice changes will lead to shifts in trophic interactions involving polar bears through reduced availability and abundance of their main prey: seals. In the short term, climatic warming may improve bear and seal habitats in higher latitudes over continental shelves if currently thick multiyear ice is replaced by annual ice with more leads, making it more suitable for seals. A cascade of impacts beginning with reduced sea ice will be manifested in reduced adipose stores leading to lowered reproductive rates because females will have less fat to invest in cubs during the winter fast. Non-pregnant bears may have to fast on land or offshore on the remaining multiyear ice through progressively longer periods of open water while they await freeze-up and a return to hunting seals. As sea ice thins, and becomes more fractured and labile, it is likely to move more in response to winds and currents so that polar bears will need to walk or swim more and thus use greater amounts of energy to maintain contact with the remaining preferred habitats. The effects of climate change are likely to show large geographic, temporal and even individual differences and be highly variable, making it difficult to develop adequate monitoring and research programs. All ursids show behavioural plasticity but given the rapid pace of ecological change in the Arctic, the long generation time, and the highly specialised nature of polar bears, it is unlikely that polar bears will survive as a species if the sea ice disappears completely as has been predicted by some. PMID:21680496

  13. A circumpolar monitoring framework for polar bears

    USGS Publications Warehouse

    Vongraven, Dag; Aars, Jon; Amstrup, S.; Atkinson, Stephen N.; Belikov, Stanislav; Born, Erik W.; DeBruyn, T.D.; Derocher, Andrew E.; Durner, George M.; Gill, Mike; Lunn, Nicholas J.; Obbard, Martyn E.; Omelak, Jack; Ovsyanikov, Nikita; Peacock, Elizabeth; Richardson, E.E.; Sahanatien, Vicki; Stirling, Ian; Wiig, Øystein

    2012-01-01

    Polar bears (Ursus maritimus) occupy remote regions that are characterized by harsh weather and limited access. Polar bear populations can only persist where temporal and spatial availability of sea ice provides adequate access to their marine mammal prey. Observed declines in sea ice availability will continue as long as greenhouse gas concentrations rise. At the same time, human intrusion and pollution levels in the Arctic are expected to increase. A circumpolar understanding of the cumulative impacts of current and future stressors is lacking, long-term trends are known from only a few subpopulations, and there is no globally coordinated effort to monitor effects of stressors. Here, we describe a framework for an integrated circumpolar monitoring plan to detect ongoing patterns, predict future trends, and identify the most vulnerable polar bear subpopulations. We recommend strategies for monitoring subpopulation abundance and trends, reproduction, survival, ecosystem change, human-caused mortality, human–bear conflict, prey availability, health, stature, distribution, behavioral change, and the effects that monitoring itself may have on polar bears. We assign monitoring intensity for each subpopulation through adaptive assessment of the quality of existing baseline data and research accessibility. A global perspective is achieved by recommending high intensity monitoring for at least one subpopulation in each of four major polar bear ecoregions. Collection of data on harvest, where it occurs, and remote sensing of habitat, should occur with the same intensity for all subpopulations. We outline how local traditional knowledge may most effectively be combined with the best scientific methods to provide comparable and complementary lines of evidence. We also outline how previously collected intensive monitoring data may be sub-sampled to guide future sampling frequencies and develop indirect estimates or indices of subpopulation status. Adoption of this framework

  14. Rolling Bearing Life Prediction, Theory, and Application

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    2013-01-01

    A tutorial is presented outlining the evolution, theory, and application of rolling-element bearing life prediction from that of A. Palmgren, 1924; W. Weibull, 1939; G. Lundberg and A. Palmgren, 1947 and 1952; E. Ioannides and T. Harris, 1985; and E. Zaretsky, 1987. Comparisons are made between these life models. The Ioannides-Harris model without a fatigue limit is identical to the Lundberg-Palmgren model. The Weibull model is similar to that of Zaretsky if the exponents are chosen to be identical. Both the load-life and Hertz stress-life relations of Weibull, Lundberg and Palmgren, and Ioannides and Harris reflect a strong dependence on the Weibull slope. The Zaretsky model decouples the dependence of the critical shear stress-life relation from the Weibull slope. This results in a nominal variation of the Hertz stress-life exponent. For 9th- and 8th-power Hertz stress-life exponents for ball and roller bearings, respectively, the Lundberg- Palmgren model best predicts life. However, for 12th- and 10th-power relations reflected by modern bearing steels, the Zaretsky model based on the Weibull equation is superior. Under the range of stresses examined, the use of a fatigue limit would suggest that (for most operating conditions under which a rolling-element bearing will operate) the bearing will not fail from classical rolling-element fatigue. Realistically, this is not the case. The use of a fatigue limit will significantly overpredict life over a range of normal operating Hertz stresses. Since the predicted lives of rolling-element bearings are high, the problem can become one of undersizing a bearing for a particular application.

  15. Mass Loss Rates of Fasting Polar Bears.

    PubMed

    Pilfold, Nicholas W; Hedman, Daryll; Stirling, Ian; Derocher, Andrew E; Lunn, Nicholas J; Richardson, Evan

    2016-01-01

    Polar bears (Ursus maritimus) have adapted to an annual cyclic regime of feeding and fasting, which is extreme in seasonal sea ice regions of the Arctic. As a consequence of climate change, sea ice breakup has become earlier and the duration of the open-water period through which polar bears must rely on fat reserves has increased. To date, there is limited empirical data with which to evaluate the potential energetic capacity of polar bears to withstand longer fasts. We measured the incoming and outgoing mass of inactive polar bears (n = 142) that were temporarily detained by Manitoba Conservation and Water Stewardship during the open-water period near the town of Churchill, Manitoba, Canada, in 2009-2014. Polar bears were given access to water but not food and held for a median length of 17 d. Median mass loss rates were 1.0 kg/d, while median mass-specific loss rates were 0.5%/d, similar to other species with high adiposity and prolonged fasting capacities. Mass loss by unfed captive adult males was identical to that lost by free-ranging individuals, suggesting that terrestrial feeding contributes little to offset mass loss. The inferred metabolic rate was comparable to a basal mammalian rate, suggesting that while on land, polar bears can maintain a depressed metabolic rate to conserve energy. Finally, we estimated time to starvation for subadults and adult males for the on-land period. Results suggest that at 180 d of fasting, 56%-63% of subadults and 18%-24% of adult males in this study would die of starvation. Results corroborate previous assessments on the limits of polar bear capacity to withstand lengthening ice-free seasons and emphasize the greater sensitivity of subadults to changes in sea ice phenology. PMID:27617359

  16. 46 CFR 61.20-23 - Tailshaft clearance; bearing weardown.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Tailshaft clearance; bearing weardown. 61.20-23 Section...; bearing weardown. (a) Water lubricated bearings, other than rubber, must be rebushed as follows: (1) Where the propelling machinery is located amidship, the after stern tube bearing must be rebushed when it...

  17. 46 CFR 61.20-23 - Tailshaft clearance; bearing weardown.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Tailshaft clearance; bearing weardown. 61.20-23 Section...; bearing weardown. (a) Water lubricated bearings, other than rubber, must be rebushed as follows: (1) Where the propelling machinery is located amidship, the after stern tube bearing must be rebushed when it...

  18. 46 CFR 61.20-23 - Tailshaft clearance; bearing weardown.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Tailshaft clearance; bearing weardown. 61.20-23 Section...; bearing weardown. (a) Water lubricated bearings, other than rubber, must be rebushed as follows: (1) Where the propelling machinery is located amidship, the after stern tube bearing must be rebushed when it...

  19. 46 CFR 61.20-23 - Tailshaft clearance; bearing weardown.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Tailshaft clearance; bearing weardown. 61.20-23 Section...; bearing weardown. (a) Water lubricated bearings, other than rubber, must be rebushed as follows: (1) Where the propelling machinery is located amidship, the after stern tube bearing must be rebushed when it...

  20. 46 CFR 61.20-23 - Tailshaft clearance; bearing weardown.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Tailshaft clearance; bearing weardown. 61.20-23 Section...; bearing weardown. (a) Water lubricated bearings, other than rubber, must be rebushed as follows: (1) Where the propelling machinery is located amidship, the after stern tube bearing must be rebushed when it...

  1. 11. 100 foot through truss north east bearing abutment ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. 100 foot through truss - north east bearing abutment of the second through truss, showing that the bearing point is to the backmost position of the concrete pier. This bearing point is on a concrete extension of the original bearing point now covered by rock and soil. - Weidemeyer Bridge, Spanning Thomes Creek at Rawson Road, Corning, Tehama County, CA

  2. 49 CFR 230.102 - Tender plain bearing journal boxes.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Tender plain bearing journal boxes. 230.102... Locomotives and Tenders Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes... expected to damage the bearing; or have a detrimental effect on the lubrication of the journal and...

  3. 49 CFR 230.102 - Tender plain bearing journal boxes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Tender plain bearing journal boxes. 230.102... Locomotives and Tenders Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes... expected to damage the bearing; or have a detrimental effect on the lubrication of the journal and...

  4. 49 CFR 230.102 - Tender plain bearing journal boxes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tender plain bearing journal boxes. 230.102... Locomotives and Tenders Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes... expected to damage the bearing; or have a detrimental effect on the lubrication of the journal and...

  5. 49 CFR 230.102 - Tender plain bearing journal boxes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Tender plain bearing journal boxes. 230.102... Locomotives and Tenders Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes... expected to damage the bearing; or have a detrimental effect on the lubrication of the journal and...

  6. 49 CFR 230.102 - Tender plain bearing journal boxes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Tender plain bearing journal boxes. 230.102... Locomotives and Tenders Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes... expected to damage the bearing; or have a detrimental effect on the lubrication of the journal and...

  7. A magnetic bearing control approach using flux feedback

    NASA Technical Reports Server (NTRS)

    Groom, Nelson J.

    1989-01-01

    A magnetic bearing control approach using flux feedback is described and test results for a laboratory model magnetic bearing actuator are presented. Test results were obtained using a magnetic bearing test fixture, which is also described. The magnetic bearing actuator consists of elements similar to those used in a laboratory test model Annular Momentum Control Device (AMCD).

  8. An aerostatic thrust bearing with a stiffness of ?

    NASA Astrophysics Data System (ADS)

    Yoshimoto, S.

    1996-03-01

    This paper proposes a new type of aerostatic thrust bearing in order to achieve 10 times larger bearing stiffness compared with that of conventional aerostatic bearings. In this bearing, a porous restrictor with 1 - 3 mm diameter is employed instead of a conventional feed-hole restrictor to restrain gas flow entering the bearing clearance to a very small amount and the proposed bearing can operate in a bearing clearance of less than 0957-4484/7/1/008/img2. The static characteristics of the proposed bearing are investigated theoretically and experimentally. It is consequently found that the proposed bearing can achieve a very high bearing stiffness of 0957-4484/7/1/008/img3.

  9. Severity estimation of cracked shaft vibrations within fluid film bearings

    NASA Astrophysics Data System (ADS)

    Prabhu, B. S.; Sekhar, A. S.

    1995-07-01

    The equations of motion, with four degrees of freedom, taking into consideration the flexibility, damping and cross coupling of the fluid film bearings are derived for a cracked Jeffcott rotor supported on fluid film bearings. Dimensionless equations are developed for dynamic radial load, dynamic pressure developed in the fluid film bearings and coefficient of dissipation considering the journal vibrations in two harmonics; bearing fluid film stiffness and damping coefficients. These are applied to a cracked Jeffcott rotor supported on different types of bearings, i.e., cylindrical journal bearings, offset cylindrical bearings, tilting pad journal bearings and three-lobe bearings. Based on the allowable dynamic pressure developed in the fluid bearings, the severity of cracked shaft and allowable crack depths are estimated in this study. Measurement of dynamic pressure and dissipation for monitoring the crack growth is suggested. However, 2x vibration is the best indicator of cracks in the shafts.

  10. Bearing assemblies, apparatuses, and motor assemblies using the same

    SciTech Connect

    Sexton, Timothy N.; Cooley, Craig H.; Knuteson, Cody W.

    2015-12-29

    Various embodiments of the invention relate to bearing assemblies, apparatuses and motor assemblies that include geometric features configured to impart a selected amount of heat transfer and/or hydrodynamic film formation. In an embodiment, a bearing assembly may include a plurality of superhard bearing pads distributed circumferentially about an axis. At least some of the plurality of superhard bearing pads may include a plurality of sub-superhard bearing elements defining a bearing surface. At least some of the plurality of sub-superhard bearing elements may be spaced from one another by one or more voids to impart a selected amount of heat transfer and hydrodynamic film formation thereon during operation. The bearing assembly may also include a support ring that carries the plurality of superhard bearing pads. In addition, at least a portion of the sub-superhard bearing elements may extend beyond the support ring.

  11. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity.

    PubMed

    Dubois, Sara; Fraser, David

    2013-01-01

    The "pot bears" received international media attention in 2010 after police discovered the intentional feeding of over 20 black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia, Canada. A two-phase random digit dialing survey of the community was conducted in 2011 to understand local perspectives on bear policy and management, before and after a summer of problem bear activity and government interventions. Of the 159 households surveyed in February 2011, most had neutral or positive attitudes towards bears in general, and supported the initial decision to feed the food-conditioned bears until the autumn hibernation. In contrast to wildlife experts however, most participants supported relocating the problem bears, or allowing them to remain in the area, ahead of killing; in part this arose from notions of fairness despite the acknowledged problems of relocation. Most locals were aware of the years of feeding but did not report it, evidently failing to see it as a serious form of harm, even after many bears had been killed. This underscores the importance of preventive action on wildlife feeding and the need to narrow the gap between public and expert opinion on the likely effects of relocation versus killing. PMID:26479542

  12. Simultaneous identification of residual unbalances and bearing dynamic parameters from impulse responses of rotor bearing systems

    NASA Astrophysics Data System (ADS)

    Tiwari, R.; Chakravarthy, V.

    2006-10-01

    An identification algorithm for simultaneous estimation of residual unbalances and bearing dynamic parameters by using impulse response measurements is presented for multi-degree-of-freedom ( mdofs) flexible rotor-bearing systems. The algorithm identifies speed-dependent bearing dynamic parameters for each bearing and residual unbalances at predefined balancing planes. Bearing dynamic parameters consist of four stiffness and four damping coefficients and residual unbalances contain the magnitude and phase information. Timoshenko beam with gyroscopic effects are included in the system finite element modelling. To overcome the practical difficulty of number of responses that can be measured, the standard condensation is used to reduce the number of degrees of freedom ( dofs) of the model. For illustration, responses in time domain are simulated due to impulse forces in the presence of residual unbalances from a rotor-bearing model and transformed to frequency domain. The identification algorithm uses these responses to estimate bearing dynamic parameters along with residual unbalances. The proposed algorithm has the flexibility to incorporate any type and any number of bearings including seals. The identification algorithm has been tested with the measurement noise in the simulated response. Identified parameters match quite well with assumed parameters used for the simulation of responses. The response reproduction capability of identified parameters has been found to be excellent.

  13. 78 FR 33433 - Bear Lake National Wildlife Refuge, Bear Lake County, ID, and Oxford Slough Waterfowl Production...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-04

    ... Fish and Wildlife Service Bear Lake National Wildlife Refuge, Bear Lake County, ID, and Oxford Slough... Bear Lake National Wildlife Refuge in Bear Lake County, Idaho, and the Oxford Slough Waterfowl... Federal Register (75 FR 35829; June 23, 2010). We released the draft CCP/EA to the public, announcing...

  14. A conventional point of view on active magnetic bearings

    NASA Technical Reports Server (NTRS)

    Chen, H. Ming; Dill, Jim

    1993-01-01

    Active magnetic bearings used in rotating machinery should be designed as locally controlled, independent devices similar to other types of bearings. The functions of control electronics and power amplifiers can be simply and explicitly related to general bearing properties such as load capacity, stiffness, and damping. The dynamics of a rotor and its supporting active magnetic bearings are analyzed in a modified conventional method with an extended state vector containing the bearing state variables.

  15. ES and H-compatible lubrication for duplex bearings

    SciTech Connect

    Steinhoff, R.G.

    1997-10-01

    Two ES and H-compatible lubricants (environment, safety, and health) for duplex bearing applications and one hybrid material duplex bearing were evaluated and compared against duplex bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in strong link mechanisms since 1974. Hybrid duplex bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, duplex bearings lubricated with sputtered MoS{sub 2} on races and retainers, and duplex bearings lubricated with electrophoretic deposited MoS{sub 2} were evaluated. Bearings with electrophoretic deposited MoS{sub 2} performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax. Hybrid bearings with silicon nitride balls performed worse than bearings lubricated with Vydax, but their performance would still be acceptable for most applications. Bearings lubricated with sputtered MoS{sub 2} on the races and retainers had varying amounts of film on the bearings. This affected the performance of the bearings. Bearings with a uniform coating performed to acceptable levels, but bearings with no visible MoS{sub 2} on the races and retainers did not perform as well as bearings with the other coatings. Unless process controls are incorporated in the sputtering process or the bearings are screened, they do not appear to be acceptable for duplex bearing applications.

  16. Method for changing removable bearing for a wind turbine generator

    DOEpatents

    Bagepalli, Bharat Sampathkumaran; Jansen, Patrick Lee; Gadre, Aniruddha Dattatraya

    2008-04-22

    A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

  17. Removable bearing arrangement for a wind turbine generator

    DOEpatents

    Bagepalli, Bharat Sampathkumaran; Jansen, Patrick Lee; Gadre, Aniruddha Dattatraya

    2010-06-15

    A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

  18. An Analysis of the Full-Floating Journal Bearing

    NASA Technical Reports Server (NTRS)

    Shaw, M C; Nussdorfer, T J , Jr

    1947-01-01

    An analysis of the operating characteristics of a full-floating journal bearing, a bearing in which a floating sleeve is located between the journal and bearing surfaces, is presented together with charts from which the performance of such bearings may be predicted. Examples are presented to illustrate the use of these charts and a limited number of experiments conducted upon a glass full-floating bearing are reported to verify some results of the analysis.

  19. Bearing tester data compilation, analysis and reporting and bearing math modeling, volume 1

    NASA Technical Reports Server (NTRS)

    Marshall, D. D.; Montgomery, E. E.; New, L. S.; Stone, M. A.; Tiller, B. K.

    1984-01-01

    Thermal and mechanical models of high speed angular contact ball bearings operating in LOX and LN2 were developed and verified with limited test data in an effort to further understand the parameters that determine or effect the SSME turbopump bearing operational characteristics and service life. The SHABERTH bearing analysis program which was adapted to evaluate shaft bearing systems in cryogenics is not capable of accommodating varying thermal properties and two phase flow. A bearing model with this capability was developed using the SINDA thermal analyzer. Iteration between the SHABERTH and the SINDA models enable the establishment of preliminary bounds for stable operation in LN2. These limits were established in terms of fluid flow, fluid inlet temperature, and axial load for a shaft speed of 30,000 RPM.

  20. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    PubMed Central

    Dubois, Sara; Fraser, David

    2013-01-01

    Simple Summary The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia. Residents of this small community were surveyed by phone twice over the following year, before and after government actions. This study aimed to understand local attitudes on how these bears should be managed and whether they differed from existing bear management policy. Results indicate a significant problem with the public view of wildlife feeding and a gap between public and expert opinion on relocation and killing of food-conditioned wildlife. Abstract The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of over 20 black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia, Canada. A two-phase random digit dialing survey of the community was conducted in 2011 to understand local perspectives on bear policy and management, before and after a summer of problem bear activity and government interventions. Of the 159 households surveyed in February 2011, most had neutral or positive attitudes towards bears in general, and supported the initial decision to feed the food-conditioned bears until the autumn hibernation. In contrast to wildlife experts however, most participants supported relocating the problem bears, or allowing them to remain in the area, ahead of killing; in part this arose from notions of fairness despite the acknowledged problems of relocation. Most locals were aware of the years of feeding but did not report it, evidently failing to see it as a serious form of harm, even after many bears had been killed. This underscores the importance of preventive action on wildlife feeding and the need to narrow the gap between public and expert opinion on the likely effects of relocation versus

  1. Conceptual Design and Feasibility of Foil Bearings for Rotorcraft Engines: Hot Core Bearings

    NASA Technical Reports Server (NTRS)

    Howard, Samuel A.

    2007-01-01

    Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include oil-free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit.. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This overview presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section. In addition, system level foil bearing testing capabilities at NASA Glenn Research Center are presented along with analysis work being conducted under NRA Cooperative Agreements.

  2. Bear bile: dilemma of traditional medicinal use and animal protection.

    PubMed

    Feng, Yibin; Siu, Kayu; Wang, Ning; Ng, Kwan-Ming; Tsao, Sai-Wah; Nagamatsu, Tadashi; Tong, Yao

    2009-01-01

    Bear bile has been used in Traditional Chinese Medicine (TCM) for thousands of years. Modern investigations showed that it has a wide range of pharmacological actions with little toxicological side effect and the pure compounds have been used for curing hepatic and biliary disorders for decades. However, extensive consumption of bear bile made bears endangered species. In the 1980's, bear farming was established in China to extract bear bile from living bears with "Free-dripping Fistula Technique". Bear farming is extremely inhumane and many bears died of illness such as chronic infections and liver cancer. Efforts are now given by non-governmental organizations, mass media and Chinese government to end bear farming ultimately. At the same time, systematic research has to be done to find an alternative for bear bile. In this review, we focused on the literature, laboratory and clinical results related to bear bile and its substitutes or alternative in English and Chinese databases. We examined the substitutes or alternative of bear bile from three aspects: pure compounds derived from bear bile, biles from other animals and herbs from TCM. We then discussed the strategy for stopping the trading of bear bile and issues of bear bile related to potential alternative candidates, existing problems in alternative research and work to be done in the future. PMID:19138420

  3. Bear bile: dilemma of traditional medicinal use and animal protection

    PubMed Central

    Feng, Yibin; Siu, Kayu; Wang, Ning; Ng, Kwan-Ming; Tsao, Sai-Wah; Nagamatsu, Tadashi; Tong, Yao

    2009-01-01

    Bear bile has been used in Traditional Chinese Medicine (TCM) for thousands of years. Modern investigations showed that it has a wide range of pharmacological actions with little toxicological side effect and the pure compounds have been used for curing hepatic and biliary disorders for decades. However, extensive consumption of bear bile made bears endangered species. In the 1980's, bear farming was established in China to extract bear bile from living bears with "Free-dripping Fistula Technique". Bear farming is extremely inhumane and many bears died of illness such as chronic infections and liver cancer. Efforts are now given by non-governmental organizations, mass media and Chinese government to end bear farming ultimately. At the same time, systematic research has to be done to find an alternative for bear bile. In this review, we focused on the literature, laboratory and clinical results related to bear bile and its substitutes or alternative in English and Chinese databases. We examined the substitutes or alternative of bear bile from three aspects: pure compounds derived from bear bile, biles from other animals and herbs from TCM. We then discussed the strategy for stopping the trading of bear bile and issues of bear bile related to potential alternative candidates, existing problems in alternative research and work to be done in the future. PMID:19138420

  4. Process for depositing Cr-bearing layer

    DOEpatents

    Ellis, T.W.; Lograsso, T.A.; Eshelman, M.A.

    1995-05-09

    A method of applying a Cr-bearing layer to a substrate, comprises introducing an organometallic compound, in vapor or solid powder form entrained in a carrier gas to a plasma of an inductively coupled plasma torch or device to thermally decompose the organometallic compound and contacting the plasma and the substrate to be coated so as to deposit the Cr-bearing layer on the substrate. A metallic Cr, Cr alloy or Cr compound such as chromium oxide, nitride and carbide can be provided on the substrate. Typically, the organometallic compound is introduced to an inductively coupled plasma torch that is disposed in ambient air so to thermally decompose the organometallic compound in the plasma. The plasma is directed at the substrate to deposit the Cr-bearing layer or coating on the substrate. 7 figs.

  5. Process for depositing Cr-bearing layer

    DOEpatents

    Ellis, Timothy W.; Lograsso, Thomas A.; Eshelman, Mark A.

    1995-05-09

    A method of applying a Cr-bearing layer to a substrate, comprises introducing an organometallic compound, in vapor or solid powder form entrained in a carrier gas to a plasma of an inductively coupled plasma torch or device to thermally decompose the organometallic compound and contacting the plasma and the substrate to be coated so as to deposit the Cr-bearing layer on the substrate. A metallic Cr, Cr alloy or Cr compound such as chromium oxide, nitride and carbide can be provided on the substrate. Typically, the organometallic compound is introduced to an inductively coupled plasma torch that is disposed in ambient air so to thermally decompose the organometallic compound in the plasma. The plasma is directed at the substrate to deposit the Cr-bearing layer or coating on the substrate.

  6. Material and tribological considerations for turbopump bearings

    NASA Technical Reports Server (NTRS)

    Wedeven, L. D.; Miller, N. C.

    1991-01-01

    The frictional heat generation in the rolling/sliding contact areas of high pressure oxygen turbopump (HPOTP) bearings is a key factor in bearing life. Several bulk materials, surface treatments and coatings are examined for their attributes of rolling contact fatigue life, wear and friction. Emphasis is given to the frictional response of these materials under conditions of rolling with incipient sliding as predicted from HPOTP bearing analysis. Rolling contact fatigue life is shown to be significantly improved with silicon nitride. Fatigue life can also be improved by coating the chromium carbide-laden stainless steels (440C, BG42) with TiN and thin dense chrome. The traction (friction under rolling/sliding) of these materials is discussed in terms of microslip and the presence of interfacial films.

  7. Robust bearing estimation for 3-component stations

    SciTech Connect

    CLAASSEN,JOHN P.

    2000-02-01

    A robust bearing estimation process for 3-component stations has been developed and explored. The method, called SEEC for Search, Estimate, Evaluate and Correct, intelligently exploits the inherent information in the arrival at every step of the process to achieve near-optimal results. In particular the approach uses a consistent framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, to construct metrics helpful in choosing the better estimates or admitting that the bearing is immeasurable, and finally to apply bias corrections when calibration information is available to yield a single final estimate. The algorithm was applied to a small but challenging set of events in a seismically active region. It demonstrated remarkable utility by providing better estimates and insights than previously available. Various monitoring implications are noted from these findings.

  8. Robust Bearing Estimation for 3-Component Stations

    SciTech Connect

    Claassen, John P.

    1999-06-03

    A robust bearing estimation process for 3-component stations has been developed and explored. The method, called SEEC for Search, Estimate, Evaluate and Correct, intelligently exploits the in- herent information in the arrival at every step of the process to achieve near-optimal results. In particular, the approach uses a consistent framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, to construct metrics helpful in choosing the better estimates or admitting that the bearing is immeasurable, andjinally to apply bias corrections when calibration information is available to yield a single final estimate. The method was applied to a small but challenging set of events in a seismically active region. The method demonstrated remarkable utility by providing better estimates and insights than previously available. Various monitoring implications are noted fiom these findings.

  9. High Performance Magnetic Bearings for Aero Applications

    NASA Technical Reports Server (NTRS)

    Allaire, P. E.; Knospe, C. R.; Williams, R. D.; Lewis, D. W.; Barrett, L. E.; Maslen, E. H.; Humphris, R. R.

    1997-01-01

    Several previous annual reports were written and numerous papers published on the topics for this grant. That work is not repeated here in this final report. Only the work completed in the final year of the grant is presented in this final report. This final year effort concentrated on power loss measurements in magnetic bearing rotors. The effect of rotor power losses in magnetic bearings are very important for many applications. In some cases, these losses must be minimized to maximize the length of time the rotating machine can operate on a fixed energy or power supply. Examples include aircraft gas turbine engines, space devices, or energy storage flywheels. In other applications, the heating caused by the magnetic bearing must be removed. Excessive heating can be a significant problem in machines as diverse as large compressors, electric motors, textile spindles, and artificial heart pumps.

  10. Evidence that bears are induced ovulators.

    PubMed

    Boone, William R; Keck, Becky B; Catlin, Jeffery C; Casey, Kevin J; Boone, Edna T; Dye, Penny S; Schuett, Randy J; Tsubota, Toshio; Bahr, Janice C

    2004-04-15

    The objective of this study was to determine if black bears are induced ovulators. We conducted a single experiment with two replicates; each replicate was divided into two arms: females exposed to male bears and females without male exposure. We used laparoscopy to examine ovaries for corpora lutea and measured serum progesterone concentrations. Six of the seven isolated females failed to ovulate, while seven of the eight females exposed to males produced one to four corpora lutea. Furthermore, isolated females had significantly lower progesterone concentrations than females exposed to males. Thus, our data suggest that the American black bear is an induced ovulator. These results may aid biologists in their efforts to reproduce ursids in controlled environments. PMID:15037003

  11. Powder metallurgy bearings for advanced rocket engines

    NASA Technical Reports Server (NTRS)

    Fleck, J. N.; Killman, B. J.; Munson, H.E.

    1985-01-01

    Traditional ingot metallurgy was pushed to the limit for many demanding applications including antifriction bearings. New systems require corrosion resistance, better fatigue resistance, and higher toughness. With conventional processing, increasing the alloying level to achieve corrosion resistance results in a decrease in other properties such as toughness. Advanced powder metallurgy affords a viable solution to this problem. During powder manufacture, the individual particle solidifies very rapidly; as a consequence, the primary carbides are very small and uniformly distributed. When properly consolidated, this uniform structure is preserved while generating a fully dense product. Element tests including rolling contact fatigue, hot hardness, wear, fracture toughness, and corrosion resistance are underway on eleven candidate P/M bearing alloys and results are compared with those for wrought 440C steel, the current SSME bearing material. Several materials which offer the promise of a significant improvement in performance were identified.

  12. Demography of the Yellowstone grizzly bears

    USGS Publications Warehouse

    Pease, C.M.; Mattson, D.J.

    1999-01-01

    We undertook a demographic analysis of the Yellowstone grizzly bears (Ursus arctos) to identify critical environmental factors controlling grizzly bear vital rates, and thereby to help evaluate the effectiveness of past management and to identify future conservation issues. We concluded that, within the limits of uncertainty implied by the available data and our methods of data analysis, the size of the Yellowstone grizzly bear population changed little from 1975 to 1995. We found that grizzly bear mortality rates are about double in years when the whitebark pine crop fails than in mast years, and that the population probably declines when the crop fails and increases in mast years. Our model suggests that natural variation in whitebark pine crop size over the last two decades explains more of the perceived fluctuations in Yellowstone grizzly population size than do other variables. Our analysis used demographic data from 202 radio-telemetered bears followed between 1975 and 1992 and accounted for whitebark pine (Pinus albicaulis) crop failures during 1993-1995. We used a maximum likelihood method to estimate demographic parameters and used the Akaike Information Criteria to judge the significance of various independent variables. We identified no independent variables correlated with grizzly bear fecundity. In order of importance, we found that grizzly bear mortality rates are correlated with season, whitebark pine crop size (mast vs. nonmast year), sex, management-trapping status (never management-trapped vs. management-trapped once or more), and age. The mortality rate of bears that were management-trapped at least once was almost double that of bears that were never management-trapped, implying a source/sink (i.e., never management-trapped/management-trapped) structure. The rate at which bears move between the source and sink, estimated as the management-trapping rate (h), is critical to estimating the finite rate of increase, I>I?. We quantified h by

  13. Hair characteristics of four Indian bear species.

    PubMed

    Sahajpal, V; Goyal, S P; Jayapal, R; Yoganand, K; Thakar, M K

    2008-03-01

    Dorsal guard hairs of four species of bear (family: Ursidae) found in India were characterized using light microscopy by studying features including colour, hair thickness, cuticle pattern, medulla pattern, medullary index, cross-section and scale count index. The gross cuticular pattern was quite similar for the four species but a distinct difference was observed in the scale count index. Medulla type was narrow and amorphous with a very low medullary index (< 0.15) except for brown bear which showed a comparatively higher medullary index (0.38) and a vacuolated medulla. By combining together the parameters mentioned above it was possible to characterize bear species on the basis of their hair characteristics. PMID:18450212

  14. Wear Analysis of Wind Turbine Gearbox Bearings

    SciTech Connect

    Blau, Peter Julian; Walker, Larry R; Xu, Hanbing; Parten, Randy J; Qu, Jun; Geer, Tom

    2010-04-01

    The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

  15. Hydrostatic shoe bearing system for the TIM

    NASA Astrophysics Data System (ADS)

    Ruiz Schneider, Elfego; Sohn, Erika; Quiros-Pacheco, Fernando; Godoy, Javier; Farah Simon, Alejandro; Quintanilla, R.; Soto, P.; Salas, Luis; Cruz-Gonzales, Irene

    2000-08-01

    We present an active, low cost hydrostatic shoe bearing system for the Mexican Infrared Telescope which solves the suspension and motion of a 100 ton, 7.8 m telescope. Different geometries are analyzed to optimize the shoe's pressure print. These designs offer a self-adjusting action between the shoe's sliding path and the girth track. Different parameters such as pressure, temperature and proximity are measured and implemented into a control system in order to stabilize the bearing from the fluid's thermal viscosity effects. A simple method for fluid injection is discussed.

  16. Method and apparatus for replacing bearing

    SciTech Connect

    Bryan, L. E.; Grove, R. W.; Primus, W. F.

    1985-07-02

    A method and apparatus are provided for replacing the bearing between the sampson post and the walking beam of an oil well pump. The walking beam and the pitman arms are securely fastened together to prevent relative movement therebetween. The head portion is adjustably restrained against the force of the counter-weight. The walking beam is allowed to pivot on the connection between the walking beam and the pitman arms so that the walking beam moves away from the sampson post so that the bearing may be replaced.

  17. A coherent frequency-bearing tracker

    NASA Astrophysics Data System (ADS)

    Ohlms, D. E.; Cohen, A. O.; Hampton, M. L.; Johnson, G. W.

    The passive measurement of target bearing can be achieved by estimating the phase difference between spatially separated observations of a narrow-band signal. The estimation of this phase difference requires algorithms to track variations in received frequency and the phase difference. This paper presents such an algorithm: a coherently coupled frequency-bearing tracker (CCFBT). The CCFBT is derived from extended Kalman filter theory. A linearized covariance analysis predicts performance above threshold, and an approximate rule predicts threshold. Simulation results verify the covariance analysis and threshold predictions.

  18. Grizzly bear habitat selection is scale dependent.

    PubMed

    Ciarniello, Lana M; Boyce, Mark S; Seip, Dale R; Heard, Douglas C

    2007-07-01

    The purpose of our study is to show how ecologists' interpretation of habitat selection by grizzly bears (Ursus arctos) is altered by the scale of observation and also how management questions would be best addressed using predetermined scales of analysis. Using resource selection functions (RSF) we examined how variation in the spatial extent of availability affected our interpretation of habitat selection by grizzly bears inhabiting mountain and plateau landscapes. We estimated separate models for females and males using three spatial extents: within the study area, within the home range, and within predetermined movement buffers. We employed two methods for evaluating the effects of scale on our RSF designs. First, we chose a priori six candidate models, estimated at each scale, and ranked them using Akaike Information Criteria. Using this method, results changed among scales for males but not for females. For female bears, models that included the full suite of covariates predicted habitat use best at each scale. For male bears that resided in the mountains, models based on forest successional stages ranked highest at the study-wide and home range extents, whereas models containing covariates based on terrain features ranked highest at the buffer extent. For male bears on the plateau, each scale estimated a different highest-ranked model. Second, we examined differences among model coefficients across the three scales for one candidate model. We found that both the magnitude and direction of coefficients were dependent upon the scale examined; results varied between landscapes, scales, and sexes. Greenness, reflecting lush green vegetation, was a strong predictor of the presence of female bears in both landscapes and males that resided in the mountains. Male bears on the plateau were the only animals to select areas that exposed them to a high risk of mortality by humans. Our results show that grizzly bear habitat selection is scale dependent. Further, the

  19. A CAD approach to magnetic bearing design

    NASA Technical Reports Server (NTRS)

    Jeyaseelan, M.; Anand, D. K.; Kirk, J. A.

    1988-01-01

    A design methodology has been developed at the Magnetic Bearing Research Laboratory for designing magnetic bearings using a CAD approach. This is used in the algorithm of an interactive design software package. The package is a design tool developed to enable the designer to simulate the entire process of design and analysis of the system. Its capabilities include interactive input/modification of geometry, finding any possible saturation at critical sections of the system, and the design and analysis of a control system that stabilizes and maintains magnetic suspension.

  20. Closure Welding of Plutonium Bearing Storage Containers

    SciTech Connect

    Cannell, G.R.

    2002-02-28

    A key element in the Department of Energy (DOE) strategy for the stabilization, packaging and storage of plutonium-bearing materials involves closure welding of DOE-STD-3013 Outer Containers (3013 container). The 3013 container provides the primary barrier and pressure boundary preventing release of plutonium-bearing materials to the environment. The final closure (closure weld) of the 3013 container must be leaktight, structurally sound and meet DOE STD 3013 specified criteria. This paper focuses on the development, qualification and demonstration of the welding process for the closure welding of Hanford PFP 3013 outer containers.