The output speed of the engine is very high, and the maximum power and maximum torque appear in a certain speed range. In order to give full play to the best performance of the engine, it is necessary to have a set of transmission devices to coordinate the speed of the engine and the actual driving speed of the wheels. The main functions of the automobile transmission are:
1. Change the transmission ratio and expand the variation range of the torque and speed of the driving wheel to adapt to the frequently changing driving conditions, and at the same time make the engine work under favorable conditions (higher power and lower fuel consumption).
2. Under the condition that the rotation direction of the engine remains unchanged, the car can be driven backwards.
3. Use the neutral gear to interrupt the power transmission, so that the engine can start, idle, and facilitate the transmission to shift gears or perform power output.