The overall structure of a car is usually composed of four parts, namely, engine, chassis, body and electrical equipment. The chassis is composed of transmission system, driving system, steering system and braking system. The transmission system is composed of clutch, gearbox, universal drive (drive shaft), main gearbox, drive axle (differential, half-shaft), etc.
    Role: From the composition of the driveline, we can easily see that the driveline of the car is actually the power transmission device between the engine and the drive wheels. It is to ensure that the car has the necessary tractive force and speed under various driving conditions, as well as to ensure that the tractive force and speed between the coordination of change and other functions, so that the car has good power and economic fuel performance, but also to ensure that the car can reverse, as well as the left and right drive wheels can adapt to the differential speed requirements, so that the power transmission can be smoothly combined or quickly separated as needed. For example, there are: starting, shifting, drive force distribution, main deceleration and deceleration differential speed and drive force direction conversion and other functions.
    Starting and clutch functions: When the vehicle is at rest and the engine drive is transferred to the input shaft of the transmission, and the drive is transferred between two rotating half-shafts with different speeds while the vehicle is in motion, it is necessary to have the function of repeatedly cutting off and connecting the engine power, which is all done by the clutch.
    Transmission function: In order to adapt to the vehicle driving state of low speed, high speed, acceleration and deceleration and to the driver's intention to manipulate, in order to achieve the engine output characteristics and fuel consumption characteristics of the speed range, it is necessary to have transmission transmission device, which is the transmission. If the drive is distributed to the front and rear wheels is done by a splitter, or called a secondary transmission. Generally, there are full-time four-wheel drive and two-wheel and four-wheel drive to switch.
    Differential function: When the vehicle is in motion, in order for the left and right drive wheels to travel on a different track, a speed difference is formed. Such as a drive wheel slippage, four-wheel drive wheel driving in the resulting speed difference, which relies on the differential to complete. There are some other functions will not be described, such as connecting the transmission of power universal transmission device.
    Car transmission system power transmission path, from the engine → clutch → transmission → universal joint → drive shaft → main reducer → differential → half shaft → drive wheels. The layout of the form of engine front drive, front drive, rear drive, rear drive and four-wheel drive.