The final drive has two functions: first, to change the direction of power transmission, and second, to act as an extension of the transmission, providing reduction ratios for different gears.
The transmission's output is a torque rotating around the longitudinal axis, while the wheels need to rotate around the vehicle's transverse axis, thus requiring a device to change the direction of power transmission. The final drive is so named because it provides a factor of the total reduction ratio in any gear. This design effectively reduces the size of the transmission, making the overall vehicle layout more rational.
The main function of an automotive final drive is to reduce speed and increase torque. By reducing the transmission speed, the output torque can be increased, thereby achieving greater driving force. Additionally, the automotive final drive can also change the direction of power output and enable differential action for the left and right wheels or the center/rear axle.
