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To obtain the simplified formula of viscous rolling resistance in the roller-raceway contact of tapered roller bearings, full EHD analyses in line contacts have been carried out for a wide range of dimensionless EHD parameters and meniscus distances in the inlet region. The results show that the effects of G and W on the viscous rolling resistance under full flooded conditions are small. However, the effects of U, G and W are influenced by the meniscus distance. The formula for frictional torque taking into account the simplified formula has been compared to the frictional torque obtained from experiment.

High speed precision ball bearings, like those used in machine tool spindles, can have serious problems associated with spin or gyroscopic moment of the rolling elements. The use of low density, silicon nitride ceramic rolling elements reduces these problems. This report presents performance test results of bearings with silicon nitride balls, and steel balls, in a high speed turbine application, using oil jet, and oil mist lubrication methods.

Fatigue life of the 6206 deep groove ball bearings has been evaluated under various thin lubricant film conditions. Endurance testing demonstrates that the fatigue life is remarkably longer than previous formal experiments. In addition, examination of flaked areas showed some to have subsurface origins, even after testing with extremely thin lubricant films. Longer fatigue life has been attributed to improvements in bearing steel quality, as well as improvements in the surface roughness of the ball bearing raceways. With thin lubricant films, the film parameter Λ, and the roughness profile have a greater influence on ball bearing fatigue life. Qualitative analysis of the rolling contact surfaces of some of the bearings after test has been carried out, and the formation of oxidized and carbonated films has been detected. These films can be considered to be contributors to longer fatigue life.

To achieve high efficiency in rear axle differentials, the reduction in friction torque of the tapered roller bearings supporting the pinion was investigated. The effects of internal geometry, and oil flow within the bearing, on friction torque were clarified. The friction torque of a newly developed bearing optimized considering various performance characteristics was 70-75% lower than that of a conventional bearing. This is equivalent to a friction torque reduction of about 80% from that of a standard bearing. This is expected to have a remarkable effect on vehicle fuel efficiency.