The drive axle is at the end of the powertrain, and its basic functions are as follows: (1) the engine torque from the universal transmission device is transmitted to the driving wheels through the main reduction tire, the differential, the half axle, etc., to achieve a decrease in speed and increase in torque; (2) through the main reducer bevel gear pair to change the direction of torque transmission; (3) Realize the difference of wheels on both sides through the differential to ensure that the inner and outer wheels are steering at different speeds.