In recent years, the demand of lower viscosity in transmission fluids has been strongly required to improve fuel efficiency. However, fatigue life of gears and bearings usually deteriorates by decreasing the viscosity of lubricating oil. Especially the impact on needle bearings that are mostly used in automatic transmissions is significant. Therefore it is very important to study about the fatigue life of needle bearing, and authors have previously reported about the influence of lubricating oil additive on a radial type. In this paper, fatigue life of a thrust needle bearing was examined using several simply formulated oils and the effect of physical properties of tribofilm on rubbed surfaces, such as composition, thickness and hardness of film, were analyzed by using microscopes and a nano-indenter. Through the bearing pitting test and the analysis of film properties, it was found that the softer and smooth film provides longer fatigue life as shear stress during rubbing may not easily accumulate in the films and the bearing materials.
|ジャーナル||Toraibarojisuto/Journal of Japanese Society of Tribologists|
|出版ステータス||Published - 2010|
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