1. Clutch (action: 1. Ensure the car starts smoothly 2. Realize smooth shifting 3. Prevent transmission system overload)
2. the transmission (action: 1. change the transmission ratio, adapt to changing driving conditions; 2. enable the car to drive backwards 3, use the neutral, interrupt the power transmission, the engine can start, idle, and shift the transmission or power output)
3. Universal transmission (action: to realize the power transmission between any axis on the vehicle where the axis intersects and the relative position changes frequently)
4. the drive axle (action: 1. increase the torque, reduce the speed, change the direction of torque transmission, that is, increase the torque transmitted by the drive shaft or directly from the transmission, and the torque is reasonably distributed to the left and right drive wheels; 2. The transaxle can also withstand vertical, longitudinal and lateral forces acting between the road surface and the frame or body, first-order braking torque and reaction torque, etc.)