The gear reducer plays the role of matching the speed and transmitting torque between the prime mover and the working machine or the actuator. It is a relatively precise machine. The purpose of using it is to reduce the speed and increase the torque. It has a wide variety of models and different types have different uses. There are many types of reducers. According to the type of transmission, it can be divided into gear reducer, worm reducer and planetary gear reducer. According to the different transmission stages, it can be divided into single-stage and multi-stage reducer. According to the shape of the gear, it can be divided into cylindrical gear reducer, bevel gear reducer and bevel-cylindrical gear reducer. According to the arrangement of the transmission, it can be divided into unfolding reducer, shunt reducer and coaxial reducer.