Tractors for towing and jacking heavy trailers. It is equipped with a high-power diesel engine, and is equipped with a large-speed mechanical or hydraulic transmission and a final drive. Some also have wheel deceleration devices to reduce vehicle speed and increase traction. Heavy-duty tractors are mostly 3-axle or 4-axle, driven by the rear two axles, and there are also full-drive front and rear axles.
When towing a full-trailer, appropriate weight must be added to the tractor to increase the load acting on the driving wheels, so that there is sufficient adhesion between the driving wheels and the ground. In general, heavy-duty trailers are towed by only one tractor; in the case of large road slopes, large cambers, and heavy cargo, two tractors can be used to tow, or one tow in the front and one to push at the back; Sometimes even multiple tractors are used to tow and push.
