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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.

Because of their smooth torque transmission, high efficiency, low noise, and high running accuracy, planetary roller type traction drive units are becoming a common, widely used a speed increaser that can achieve rotational speeds of ten thousand RPM, or a speed reducer that has very small angular velocity fluctuation. When it is utilized as a transmission, particularly grease lubrication, traction damage is caused by excessive torque load and lubricant deterioration. This paper examines traction damage caused by torque load, using a machine tool high rotational speed planetary roller type traction drive unit with grease lubrication, and the practicality of an oil film monitor using electrical resistance, and direct current power source for monitoring the oil film condition of traction surface.

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.

Nowadays, bearings for motorcycle engines are required to be compact and light weight and have a considerably high performance. In order to meet these requirements, two measures were developed, that is High Refining Steel (HRS) and Special Heat Treatment (SH Treatment). In this paper described are the characteristics of HRS and SH Treatment and the results of investigation on them. The investigation results show that bearings of HRS and bearings with SH Treatment have more than twice longer life than standard bearings, particularly the bearings with SH Treatment have longer life even under lubricating conditions with a low viscous lubricating oil or with a contaminated lubricating oil. As a matter of fact, the bearings of HRS and the bearings with SH Treatment are used for the motorcycle engines and show excellent performances.