Gearbox is a device to change the running speed of a car. It is divided into manual gearbox, ordinary automatic gearbox, CVT stepless gearbox, double clutch gearbox and AMT gearbox. The gearbox is composed of two parts: the transmission mechanism and the control mechanism. The main function of variable speed transmission mechanism is to change the value and direction of torque and speed; The main function of the control mechanism is to control the transmission mechanism and realize the variable speed torque.
The transmission plays the following roles in vehicle driving:
1. It enables the car to drive at a very low stable speed, which is difficult to achieve only by the lowest stable speed of the internal combustion engine;
2. The reverse gear of the gearbox enables the car to drive in reverse;
3. Its neutral gear enables the vehicle to separate the engine from the transmission system for a long time when starting the engine, stopping and taxiing