What is the difference between a full trailer, a semi-trailer and a centre axle trailer?

▎Brief description of trailer form

(1) Full Trailer

From the analysis of the structure of the full trailer, it is mainly composed of a frame, a cargo box, an axle, a bogie, and a traction device. We can think of it as a vehicle without a power system, and the bogie and the traction device are also the main parts that distinguish the trailer from the central axle trailer.

The front axle of the trailer is used to support the steering, and the front axle is integrated with the bogie and the traction device to turn in the direction of the main vehicle. It is worth mentioning that this traction device also supports up and down movement, which will be more stable when passing through undulating road conditions. Because of this, the main vehicle of the full trailer does not need to bear the weight of the trailer, but only needs to provide power to it. Even with the braking system, the full trailer is owned by itself. When the air pipe is unplugged when the vehicle is parked for a long time, the trailer can be steadily stopped and waited for the arrival of the main vehicle.

Of course, the device of a full trailer also has a big disadvantage. Its reversing is too difficult, and the technical requirements for the driver are very high. Compared with the reversing method of a center axle trailer and a semi-trailer, it needs a longer adaptation time. Full trailers were gradually eliminated after 2012.

Its driving stability is also limited. Road transportation emphasizes efficiency and safety. However, full trailers are affected by structural defects, and the disadvantages of poor high-speed driving stability gradually appear. In the end, it was prohibited from driving into high-speed in many areas. It has therefore become the history of the transportation industry.

(2) Centre axle trailer

Compared with the full trailer, the centre axle trailer is closer to the semi-trailer. The axles of the centre axle trailer are concentrated in the middle of the cargo box. The biggest difference between it and the full trailer is that it does not have a bogie, and the traction device is also Fixed.

Therefore, the centre axle trailer does not have a separate steering function, and can only use the tractor to perform steering activities and load.

Therefore, the centre axle trailer must be firmly attached to the tractor. Once it leaves the tractor, it cannot act alone. Since the structure of the centre axle trailer is closer to a semi-trailer, it is also simpler than a full trailer in terms of reversing. The trailer needs to use the direction of the tractor as the steering wheel to control the rotation of the trailer's towing frame, while the centre axle trailer only needs to be like a semi-trailer.

However, the centre axle trailer also has certain drawbacks. First, its traction device cannot move up and down, so when passing through bad road conditions, there are great restrictions on the trafficability of the vehicle. When parking alone, the outriggers should be lowered like a semi-trailer. There are higher requirements for the power of the tractor and the load-bearing capacity of the chassis. After all, the centre axle trailer does not have a separate load-bearing capacity.

In terms of stability, mid-axle trailers are much more stable than full trailers, but if the speed is too fast, it is prone to tail-flicking and cannot complete the task of heavy-duty driving. We personally think that the mid-axle trailer is more suitable for car transport and express transportation, because it has an advantage in the length of the vehicle.

（3）Semi-trailer

As the most common trailer currently on the market, the development of semi-trailers is very mature. Compared with full-trailers and central axle trailerss, semi-trailers are much more stable and easier to use in reversing.

The But semi-trailer also has structural drawbacks. Since the load-bearing axles of the trailer are all concentrated in the rear, the loading weight is evenly distributed to the tractor and the main vehicle, so the power and chassis load-bearing performance of the tractor are improved.

Since the semi-trailer also has no independent driving capability, it has to be towed by the tractor. As long as the driving wheel of the tractor slips, the tractor cannot drag the trailer behind. When passing a road with a steep slope, the trailer driving wheel is also prone to slipping. Even when the cargo is loaded at the rear, the trailer is affected by the undulating angle of the road surface, and it is very common that the tail of the tractor is lifted.

The stability of high-speed driving is worthy of recognition. For the current efficient logistics and transportation, the maturity of semi-trailers is relatively high. Some minor drawbacks of detailed design are acceptable to everyone, so this is the reason why it can occupy the market. , At the same time, there are more types of semi-trailers, covering: container type, tank type, flatbed, high and low bed, stake truck, etc., for users to choose more abundantly.

▎Which fields are used for centre axle trailers and semi-trailers

Centre axle trailer adaptation field: In addition to its prestige in the field of car transport, centre axle trailers can also be used in flatbed, warehouse grid, and van trailers.

Therefore, the use of centre axle trailers can be broadened to include electrical appliances, auto parts, daily necessities, foam, vehicles, etc., covering people's daily life of eating and drinking, and even the introduction of centre axle cold chain transport vehicles. In recent years, due to the continuous increase in temperature, the market for refrigerated trucks in the future is very good.

Semi-trailer application field: the total length of the centre axle trailer has advantages, but the semi-trailer is more versatile in terms of versatility, especially for heavy-load cargo transportation. The centre axle trailer is suitable for some light-load and standard-load transportation, and this kind of cargo needs larger cargo box, so the length advantage of the centre axle trailer can be used more effectively.

Conversely, the transportation of coal, cement, steel pipe, wood, feed, stone and other goods must be completed by semi-trailers, especially in the field of dangerous goods transportation. The reason why the centre axle trailer has not been widely promoted is probably because of its structure and the driving stability is slightly inferior to that of the semi-trailer. At the same time, the body length and turning flexibility of the centre axle trailers are still not as good as the semi-trailer. Therefore, the two have their own advantages. Generally speaking, semi-trailers are easier to adapt to the market.