The use of gears in reducers: The role of gears in reducers is to reduce speed, increase torque, and change the direction of power output. The output power of the engine is constant. When the transmission speed is reduced through the main reducer, higher output torque can be obtained, thereby obtaining greater driving force. In addition, the function of changing the direction of power output of reduction gears can achieve differential between left and right wheels or the middle and rear axles.