A tractor is a self-propelled power unit used for牵引 and driving machinery to perform various mobile operations. It can also serve as a stationary power source. It consists of systems or components such as the engine, transmission, movement, steering, hydraulic suspension, power output, electrical instruments, driving controls, and traction. The engine power is transmitted to the driving wheels through the transmission system, enabling the tractor to move. In real life, rubber belts are commonly used as the medium for power transmission. Tractors are categorized by function and application into agricultural, industrial, and special-purpose tractors; and by structural type into wheeled, tracked, boat-shaped tractors, and self-propelled undercarriages.