Working clearance is an important quality index of rolling bearings, and it is also an important parameter in bearing applications. In actual use, the working clearance of the bearing will affect the load distribution, vibration, noise, friction torque and life of the bearing. Especially in the combined reducer running at high speed, once the working clearance of the bearing is not adjusted properly, the operation of the gear will be unstable, vibration will occur, the meshing effect of the gear will be destroyed, and the fatigue of the gear will be aggravated. Even when the outer ring of the bearing rotates, the lining is worn, and the center distance of the gear and the backlash of the gear increase or decrease, resulting in the breakage of the gear teeth.