The reducer is an independent closed transmission device between the prime mover and the working machine, which is used to reduce the speed and increase the torque to meet the work needs, and is also used to increase the speed in some occasions, which is called the accelerator. When choosing a reducer, it should be based on the selection conditions of the working machine, technical parameters, the performance of the power machine, economy and other factors to compare the profile size, transmission efficiency, carrying capacity, quality, price of different types and varieties of reducers, and choose the most suitable reducer. The reducer is a relatively precise machine, and the purpose of using it is to reduce the speed and increase the torque. The reducer is mainly composed of transmission parts (gear or worm), shaft, bearing, box and its accessories.