Abstract
Automatic transmission fluid of the improvement in control performance is increasing however, it also has characteristic which is not desirable for the lubrication of the gears. Tooth surface failures of carburized gears such as contact fatigue have begun to increase for this reason. In this study, the pitting fatigue strength tests were conducted using the carburized gears with two methods of tooth surface strengthening. These were shot peening and manganese phosphate film treatment after shot peening. Three kinds of automatic transmission fluids were used. Development of the pitting of gears as influenced by the difference in lubricating oil and the relation of gear wear was investigated by the experiments.
