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Results for “BALL BEARING”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Long life, high speed, thrust-load ball bearings

Long-term bearing operation at three million DN can be achieved with high degree of reliability using full combination of sophisticated but currently available state-of-the-art bearing materials and designs, lubricants, and lubricating techniques.

Signer, H.↗
NASA NTRS1976

An evaluation of grease ball bearing lubricants in vacuum

Because many future spacecraft will require mechanisms to operate for long periods of time in environments which are inimical to most bearing lubricants, a series of tests has been started to evaluate 25 grease type lubricants in R-4 size bearings in vacuum at ambient temperature for a 1 year period. Four repetitions of each test are made to provide statistical samples. These tests will be used to select from two to five lubricants for 5 year tests in the same environment. At the present time fifteen test sets have been completed and five sets are being tested. The best results to date have been obtained with perfluoropolyether greases.

Demorest, K. E.↗
NASA NTRS1975

Elastohydrodynamic lubrication in an instrument ball-bearing

The paper deals with experimental measurement of bearing torque and 'percentage of lubrication' in instrument size (R6) bearings. The primary parameter found to affect bearing performance for several lubricant investigations is base viscosity. Inference of EHD film thickness is made from the percentage of film measurements which are compared with X-ray data. A reasonable correlation between the two types of data is presented, thereby, paving the way toward the use of the more universally applicable percentage of film measurements for the determination of EHD conditions in real bearing systems.

Kannel, J. W.↗
NASA NTRS1976

An evaluation of grease type ball bearing lubricants operating in various environments /Status report no. 2/

Because many future spacecraft or space stations will require mechanisms to operate for long periods of time in environments which are inimical to most bearing lubricants, a series of tests has been started to evaluate 25 grease type lubricants in R-4 size bearings in five different environments for a 1 year period. Four repetitions of each test are made to provide statistical samples. These tests will be used to select from two to five lubricants for 5 year tests in the same environments. At the present time, approximately 30 test sets have been completed and 25 sets are underway. To date, best results in all environments have been obtained with a high viscosity index perfluoropolyether grease.

Demorest, K. E.↗
NASA NTRS1978

An evaluation of grease type ball bearing lubricants operating in various environments

Because many future spacecraft or space stations will require mechanisms to operate for long periods of time in environments which are adverse to most bearing lubricants, a series of tests is continuing to evaluate 29 grease type lubricants in R-4 size bearings in five different environments for a 1 year period. Four repetitions of each test are made to provide statistical samples. These tests have also been used to select four lubricants for 5 year tests in selected environments with five repetitions of each test for statistical samples. At the present time, 65 test sets have been completed and 23 test sets are underway. Two (5 year) tests have already been started in (1) continuous operation and (2) start-stop operation, with both in vacuum at ambient temperatures. To date, in the 1 year tests, the best results in all environments have been obtained with a high viscosity index perfluoroalkylpolyether grease.

Mcmurtrey, E. L.↗
NASA NTRS1978

Predicted and experimental performance of jet-lubricated 120-millimeter-bore ball bearings operating to 2.5 million DN

Bearing inner- and outer-race temperatures and friction power losses were calculated using two computer programs. The values obtained were compared with previously reported experimental data for 120 mm bore bearings which operated at thrust loads to 22 240 N (5000 lb), shaft speeds to 20 800 rpm, and with two lubricant flow rates. One program severely underestimated the power loss, while the other, called SHABERTH, provided a good prediction of both race temperatures and power losses.

Coe, H. H.↗
NASA NTRS1979

An evaluation of grease type ball bearing lubricants operating in various environments

Grease type lubricants in bearings were evaluated in five different adverse environments for a one year period. Four repetitions of each test were made to provide statistical samples. These tests were then used to select four lubricants for five year tests in selected environments with five repetitions of each test for statistical samples. Three five year tests were started in (1) continuous operation; (2) start-stop operation, with both in vacuum at ambient temperatures; and (3) continuous operation at 93.3 C. To date, in the one year tests, the best results in all environments were obtained with a high viscosity index perfluoroalkylpolyether grease.

Mcmurtrey, E. L.↗
NASA NTRS1980

Measuring ball-bearing loads

Contour of wear-path boundary in bearing race gives precise information about magnitude, direction and imbalance of load. Simple tool measures height of path perimeter as bearing race is rotated manually on flat surface.

Butner, M. F.↗
NASA NTRS1981

An evaluation of grease type ball bearing lubricants operating in various environments

Because many future spacecraft or space stations will require mechanisms to operate for long periods of time in environments which are adverse to most bearing lubricants, a series of tests is continuing to evaluate 38 grease type lubricants in R-4 size bearings in five different environments for a 1 year period. Four repetitions of each test are made to provide statistical samples. These tests were used to select four lubricants for 5 year tests in selected environments with five repetitions of each test for statistical samples. At the present time, 100 test sets are completed and 22 test sets are underway. Three 5 year tests were started in (1) continuous operation and (2) start-stop operation, with both in vacuum at ambient temperatures, and (3) continuous operation at 93.3 C. In the 1 year tests the best results to date in all environments were obtained with a high viscosity index perfluoroalkylpolyether (PFPE) grease.

Mcmurtrey, E. L.↗
NASA NTRS1982

Determination of ball bearing dynamic stiffness

The dynamic radial stiffness characteristics of rolling element bearings are currently determined by analytical methods that have not been experimentally verified. These bearing data are vital to rotating machinery design integrity because accurate critical speeds and rotor stability predictions are highly dependent on the bearing stiffness. A tester was designed capable of controlling the bearing axial preload, speed, and rotor unbalance. The rotor and support structures were constructed to permit critical speeds that are predominantly determined by a 57 mm test bearing. A curve of calculated critical speed versus stiffness was used to determine the actual bearing stiffness from the empirical data. The results of extensive testing are used to verify analytical predictions, increase confidence in existing bearing computer programs, and to serve as a data base for efforts to correct these programs.

Beatty, R. F.↗
NASA NTRS1983

An evaluation of grease-type ball bearing lubricants operation in various environments

Because many future spacecraft or space stations will require mechanisms to operate for long periods of time in environments which are adverse to most bearing lubricants, a series of tests is continuing to evaluate 38 grease type lubricants in R-4 size bearings in five different environments for a 1 year period. Four repetitions of each test are made to provide statistical samples. These tests have also been used to select four lubricants for 5 year tests in selected environments with five repetitions of each test for statistical samples. At the present time, 142 test sets have been completed and 30 test sets are underway. The three 5 year tests in (1) continuous operation and (2) start stop operation, with both in vacuum at ambient temperatures, and (3) continuous vacuum operation at 93.3 C are now completed. To date, in both the 1 year and 5 year tests, the best results in all environments have been obtained with a high viscosity index perfluoroalkylpolyether (PFPE) grease.

Mcmurtrey, E. L.↗
NASA NTRS1984

An evaluation of grease type ball bearing lubricants operating in various environments

Because many future spacecraft or space stations will require mechanisms to operate for long periods of time in environments which are adverse to most bearing lubricants, a series of tests has been completed to evaluate 38 grease type lubricants in R-4 size bearings in five different environments for a 1 year period. Four repetitions of each test were made to provide statistical samples. These tests were also used to select four lubricants for 5 year tests in selected environments with five repetitions of each test for statistical samples. In this completed program, 172 test sets have been completed. The three 5 year tests in: (1) continuous operation and (2) start stop operation, with both in vacuum at ambient temperatures, and (3) continuous vacuum operation at 93.3 C have been completed. In both the 1 year and 5 year tests, the best results in all environments have been obtained with a high viscosity index perfluoroalkylpolyether (PFPE) grease.

Mcmurtrey, E. L.↗
NASA NTRS1988

Predicting Temperatures In Ball Bearings

Computer simulations speed design studies. Analyses performed in two or three dimensions. Sizes and shapes of components approximated by zones or nodes connected by gridlines. From geometric information about grids and boundary conditions, properties of bearing and lubricant materials, and information supplied by users, thermal-analysis programs generate mathematical models for thermal transport. Thermal analysis of high-speed rolling contact bearings matured so much that computerized numerical simulations replace expensive time consuming full scale experiments.

Wagner, William R.↗
NASA NTRS1990

Computation of Space Shuttle high-pressure cryogenic turbopump ball bearing two-phase coolant flow

A homogeneous two-phase fluid flow model, implemented in a three-dimensional Navier-Stokes solver using computational fluid dynamics methodology is described. The application of the model to the analysis of the pump-end bearing coolant flow of the high-pressure oxygen turbopump of the Space Shuttle main engine is studied. Results indicate large boiling zones and hot spots near the ball/race contact points. The extent of the phase change of the liquid oxygen coolant flow due to the frictional and viscous heat fluxes near the contact areas has been investigated for the given inlet conditions of the coolant.

Chen, Yen-Sen↗