Tractors are used for self-propelled power machines that haul and drive work machines to complete all kinds of mobile work. They can also do fixed work power, from engines, transmissions, walking, steering, hydraulic suspension, power output, electrical instrumentation, driving controls and traction, etc. The system or device is composed of the engine power transmitted from the transmission system to the driving wheel to drive the tractor. In real life, the rubber belt is often used as the power transmission medium. According to the function and use of agricultural, industrial and special purpose tractors; according to the structure of the type of wheel, crawler, boat tractor and self-propelled chassis.