Tractor is a general large truck or semi-trailer that is towed by a tool between the head and the box, that is, the head of the
Car can be detached from the original box and tow other boxes, and the box can also be pulled away from the original head and pulled by other heads. . The front of the car with driving ability is called a tractor, and the car without traction driving behind is called a trailer. The trailer is towed by the tractor. There are two ways to connect the tractor and the trailer: the first is that the front half of the trailer is placed on the traction saddle above the rear section of the tractor, and the bridge behind the tractor bears part of the weight of the trailer, this is the semi-trailer; the second In this case, the front end of the trailer is connected to the rear end of the tractor. The tractor only provides forward pulling force and drags the trailer, but does not bear the downward weight of the trailer. This is the full trailer. [1]
It is often used for the transportation of large quantities of goods within or between workshops, such as the transportation from the warehouse of the automobile manufacturing industry to the assembly line, and the luggage transportation at the airport.
According to whether the support can move, it is divided into fixed type, mobile type and lifting type. The left and right two supports of the fixed traction seat are fastened on the traction seat base by bolts, and the base of the traction seat is fixed to the beam of the tractor. The fixed type is the most widely used. There are many types of mobile traction seats, and the structure is almost the same as that of the fixed type. The main reason is that the connection between the base of the traction seat and the beam of the tractor adopts a porous or toothed design. The base of the traction seat can be moved forward and backward according to the needs of the trailer. Connect smoothly with different trailers. Some mobile traction seats are also equipped with automatic air pressure control device, which can push the traction seat to move forward and backward in the chute by air pressure. Lifting traction seats are mainly used on tractors in port terminals. The traction seats can move up and down within a certain range to adapt to semi-trailers of different heights.
According to different degrees of freedom, there are single degrees of freedom and double degrees of freedom. Single-degree-of-freedom traction seat is also called single-axis traction seat. It can only make a longitudinal tilt of about 80. This type of traction seat has high driving stability and is suitable for high-speed, light-load and high center of gravity semi-trailers driving on better roads. The disadvantage is that because the frame cannot swing horizontally, the torque on the frame is large. The two-degree-of-freedom traction seat is also called a two-axis traction seat. It can do horizontal and vertical swings, and can protect the frame of heavy transport tractors in different road environments. Generally, the dual-axis traction seat is much higher than the single-axis type, and the lateral stability is not good during the high-speed turning of the vehicle. Therefore, this type of traction seat is rarely used in ordinary road transportation.
