A tractor-trailer is a vehicle that has no drive capability of its own and is mainly used to provide cargo loading space and load-bearing capacity. It relies on the traction power provided by the tractor in front to achieve travel. There are two interpretations of tractor-trailer according to the literal meaning, one is a transport vehicle, and the other is a trailer for towing small vehicles. With the continuous development of the automobile industry, more and more traction models are gradually emerging.
Tractor trailers can be mainly divided into the following categories:
1. Semi-trailer:
Semi-trailer is the most widely used type of carriage in domestic road transportation. Its axle is installed at the rear of the carriage. Therefore, it cannot stand stably independently. It is necessary to place the front section of the carriage on the tractor and rely on the support provided by the tractor to maintain the semi-trailer. upright. In other words, the tractor needs to install a special traction saddle behind the body to bear part of the weight of the semi-trailer and provide traction power at the same time. After the semi-trailer compartment is separated from the tractor, special outriggers are needed for support.
Semi-trailers can be subdivided into flat type, gooseneck type, concave beam type, warehouse type, fence type, van type, container type, tank type, dump type, skeleton type and other types. Their high-speed driving stability is relatively high. Strong, simple main-hook matching, flexible application, strong load-bearing capacity, especially suitable for long-distance transportation and high-grade highway transportation, without steering device.
2. Full trailer.
A full trailer is opposite to a semi-trailer. The biggest difference is that a full trailer can stand independently. The installation distribution of its axles can bear the weight of the carriage evenly, so it can stand upright smoothly even if it is not connected to the tractor. The tractor in front only needs to provide traction power, so it can be connected with a hitch.
A typical full trailer generally consists of a frame, cargo platform (top), drawbar (frame), steering device, suspension, braking system, signaling system, etc. Compared with semi-trailers, full trailers have greater driving stability in mountainous areas or rough roads, mainly due to the fact that the drawbar or drawbar between it and the tractor can swing up, down, left and right. However, the shortcomings are relatively obvious. It has poor stability when driving at high speeds and is prone to accidents such as brake drift and tractor breakage. Therefore, it is mainly used for transportation in docks, factories, ports and other areas.
3. Center-axle trailer.
A center-axle trailer refers to a trailer whose axle is located in the center of the center of gravity of the carriage. It cannot independently support its own weight when separated from the tractor. It is mainly composed of a carriage, a traction device, and an axle. The connection device with the tractor can swing left and right, but cannot go up and down. move.
Compared with other trailers, center-axle trailers have the characteristics of low center of gravity, light weight, and simple structure. However, because they are only suitable for use on high-grade highways, they are more suitable for fixed dedicated line transportation. According to the GB1589 standard, center-axle trailers have certain advantages in terms of outer dimensions. With continuous development, they may be able to change the status quo of semi-trailers that stand out.
4. Light tractor trailer.
Unlike other tractor-trailers, the main function of light-duty tractor-trailers is not to transport goods. For example, residential trailers, which we often call RVs, can be towed by passenger cars or light trucks, and their applications are more extensive and convenient.
Light tractor-trailers can be subdivided into light tractor semi-trailers and light center-axle tractor trailers. From a functional point of view, light traction semi-trailers have stronger carrying capacity and smoother driving; light center-axle traction trailers can stand independently and stably, but when the center-axle carriage has a large load, it encounters lateral winds when driving at high speed. Easy to offset.