It is possible to improve the service life by 25% by shot peening the tooth surface. For gears with high sliding speed, sulphurizing treatment is carried out to improve their wear resistance. The temperature during sulphurizing treatment is low, so it will not cause gear deformation. After sulphurizing, the friction coefficient can be significantly reduced, so even if the lubrication condition is poor, the gear will be prevented from being killed, glued and scratched.