Study of Low Viscosity ATF with Extending Gear Fatigue Life

Although it has been reported that the increase of base oil viscosity and the selection of suitable VII (Viscosity Index Improver) are key factors to improve metal fatigue life for the development of low viscosity ATF, the problem of gear fatigue life has not been perfectly solved. In this study, the effect of VII on gear fatigue life was evaluated by using EHD film thickness measurement and the block on ring friction tester. Based on the study, the low viscosity ATF that has good anti-pitting performance in gears can be proposed by optimizing the combination of base oil and VII.