tractor is a self-propelled motor used to draw and drive working machines for various mobile operations. Can also do fixed work power. By the engine, transmission, walking, steering, hydraulic suspension, power output, electrical instruments, driving control and traction and other systems or devices. 

The engine power is transmitted from the transmission system to the driving wheel to make the tractor run. In real life, the rubber belt is commonly used as the medium of power transmission. According to the function and use of agricultural, industrial and special purpose tractors; According to the structure type, it can be divided into wheel type, crawler type, boat type tractor and self-moving chassis. Although the tractor is a kind of more complex machine, its type and size also differ, but they are composed of three major parts of engine, chassis and electrical equipment, each is indispensable. 

Engine is a tractor generating power device, its role is to convert the heat energy of fuel into mechanical energy to output power. The farm tractor that our country produces uses diesel engine mostly. The chassis is the device through which the tractor transmits power. Its function is to transfer the power of the engine to the driving wheel and the working device to make the tractor run, and complete the mobile operation or fixed role. 

This function is through the transmission system, walking system, steering system, braking system and working device to cooperate with each other, coordination work to achieve, at the same time they constitute the skeleton and body of the tractor. Therefore, we call the above four systems and one device collectively chassis. That is to say, in the whole tractor, except for the engine and electrical equipment, all other systems and devices, collectively referred to as the tractor chassis. Electrical equipment is a device to ensure the electricity of the tractor. Its role is to solve lighting, safety signals and engine starting.