The morphology of micro-pitting and macro-pitting, micro-pitting occurrence, development and tendency under different stress levels as well as the distributions of stress of surface and subsurface are contrast analyzed.

The equivalent cylindrical rollers experiment is carry out to investigate the fatigue pitting under EHL conditions by using a cylindrical roller test machine.

The shear stress of subsurface is crucial factor leading to tooth surface pitting. Pitting and micro-pitting are gradual fatigue phenomena under the action of the shear stress.