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Trailers can be divided into full trailers and semi-trailers. What is the difference between them? What are their characteristics?
1. Definition of trailers, full trailers and semi-trailers
1) Definition of trailers
Trailers means a vehicle towed by a tractor/truck/car without its own power drive. A tractor/truck/car can tow one or more trailers. The truck or tractor is called the master vehicle. The towed section is called a trailer.
The combinations of a tractor/truck/car and a trailer/trailers are the important vehicle transportation type in modern society, which is very effective and simple means to improve economic benefits. It has the advantages of rapidity, mobility, flexibility and safety.
2) Definition of semi-trailers
Semi-trailer is a trailer whose axles are placed behind the center of gravity of the vehicle (when the vehicle is evenly loaded) and is equipped with a coupling device (king pin) that can transmit horizontal and vertical forces to the tractor. Part of the total load of the trailer is borne by the tractor.
3)Definition of full trailers
Full trailer is a kind of trailer which has no power, the vehicle body is equipped with front and rear axles, and can independently bear its own load.
In addition, there is a full trailer with one or two axles at the middle or rear of the vehicle body, and there is a jack to support in the front of vehicle body.
Full Trailer with 1-axle
Full Trailer with 2-axle
2. There are four main differences between a semi-trailer and a full trailer
1) The connection mode and stress characteristics of the trailer body and the tractor are different
The full trailer is connected with the tractor(heavy towing truck) through a simple hook. The tractor/truck does not need to bear the trailer load, just only provides dynamic tension to help the trailer overcome the road friction resistance. Therefore, the stress characteristic of the connection is mainly the tensile force in the horizontal direction.
The semi-trailer needs a support point provided by the tractor（heavy towing Truck). In addition to providing power, the tractor also needs to bear about half of the load of the semi trailer. Therefore, the force at the coupling(king pin and fifth wheel) of semi-trailer is not only the tensile force in the horizontal direction but also the supporting force in the vertical direction provided by the tractor. Therefore, the special tractor generally has more than two axles.
2) Upright (independent parking) mode is different
The full trailer is generally in a two axles layout. The axles are distributed at the front and rear of its body, so it has the ability to stand upright (park independently) relying on its own tires.
The axle of semi-trailer is generally composed of multiple axles and concentrated in the rear of the body. It must rely on the front landing gear to achieve its own upright (independent parking) state.
3) Different components
Full Trailer: it is composed of a complete set of chassis, body, towing device, steering device, suspension, walking system, braking system and signal system.
Semi Trailer: compared with full trailer, there is no steering device, but king pin is added; there is no axle in front, but the front support device (landing gear) is added. The front structure is relatively simple, so that the frame floor can be arranged lower and has the advantage of low center of gravity.
4) Different usage scenarios
The full trailer is mainly used for short-distance transportation in farms, factories, families, companies, ports, docks, warehouses and other fields.
Common full trailers are as follows :
boat-trailers, livestock trailers, cargo trailers, RV trailers, travel trailers, utility trailers....
The semi trailers are mainly used for long-distance transportation of goods.
Common semi trailers are as follows:
Skeleton semi trailers , flatbed semi trailers, fence semi trailers , dumping semi trailers, van semi trailers, lowbed semi trailers , warehouse grid semi trailers , fuel tank semi trailers , bulk cement semi trailers, car transportation semi trailers....
3-axle Skeleton Semi Trailer for Container
3-axle Flatbed Semi Trailer for Container
3-axle Fence Semi Trailer
3-axle Dumping Semi Trailer
3-axle Van Semi Trailer for Bulk Cargo
3-axle LowbedSemi Trailer for Equipment Transportation
3-axle Warehouse Grid Semi Trailer for Bulk Cargo
3-axle Fuel Tank Semi Trailer
3-axle Bulk Cement Semi Trailer
2-axle Car Transportation Semi Trailer
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