This paper described a study on effects of the case depth, the helix angle and the carburized part on the bending fatigue strength and the bending fatigue crack path of case-carburized helical gears. Bending fatigue tests of case-carburized helical gear pairs of different case depths, helix angles and carburized parts, meshed at the worst loading position where the maximum root stress was considered to occur, were carried out, and S-N curves were obtained. Effects of the case depth, the helix angle and the carburized part on the bending fatigue strength and the bending fatigue crack path of case-carburized helical gears were determined.
