How The Semi Trailer Is Made

How The Semi Trailer Is Made

We can see many kinds of semi trailer of various sizes on the highway, including 3 axle flatbed semi trailer, livestock semi trailer, 40ft container semi trailer, etc. Do you know how these trailers are made?

How The Semi Trailer Is Made

Purchase steel

The trailer is welded from 4-5 tons of various types of steel, of which the girder must be high-strength steel, which is generally supplied by large steel plants at home and abroad.


The purchased steel needs to be cut into various shapes according to the designed size. Many steels are cut accurately and efficiently by automatic underwater plasma cutting machines.


Press the web of the girder, the cross beam of the trailer, the side beam and the column with stamping machines, bending machines and other equipment.

Welding semi trailer girder

The cut parts need to be welded together. Some large factories have been equipped with automatic welding robots, and the effect is fast and good.

How The Semi Trailer Is Made

Skeleton assembly

The longitudinal beam, cross beam and side beam of the trailer are welded together, and the skeleton of the semi-trailer is basically completed.

Install suspension

Then start welding the suspension part of the trailer, which is the most critical part of the trailer’s load-carrying capacity, and will be combined with the driving system later.

Floor laying

At present, there are mainly two kinds of manual welding soleplates for trailers: flat plates and checkered plates. The friction of checkered plates is relatively large, and customers can customize them according to the characteristics of their own goods.

Install column

If it is a barn trailer, then the column needs to be installed next. In this step, some are fixed with screws, and some are directly welded. These two methods have their own advantages and disadvantages.

How The Semi Trailer Is Made

Wing panels and rails

This is a labor-intensive work, most of which adopts manual welding. Some manufacturers also outsource these things to other processing plants.

Install the door rail

After the manufacturing of all kinds of fence doors is completed, they are welded to the trailer, and the appearance of the trailer is basically complete.

Install the outrigger

Outriggers are used when parking trailers. Most trailers will not manufacture such parts in person, and most of them are supplied by specialized manufacturers, such as Jost, etc.

Sand blasting and derusting

Before painting, the trailer will be sandblasted to remove the rust on the trailer. After painting, the anti rust ability of the trailer can be greatly enhanced.

How The Semi Trailer Is Made


Paint the trailer according to the needs of customers. At present, most Trailer factories use manual painting. A trailer needs to be painted 2-3 times. This kind of work is very dirty and tiring.

Axle installation

The trailer factory purchases the trailer axle from Fuhua, BPW and other manufacturers, and then installs it on the trailer.

Install tires

tires are a major consumable of trailers. Users can generally purchase tires of designated brands or purchase tires by themselves for installation.

Circuit air circuit

Finally, after installing the circuit, air circuit and ABS brake debugging, a complete semi-trailer was born.

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