The rear axle of a semi-trailer is a typical driven axle, which is mainly used for load bearing and auxiliary braking. Compared with the driving steering axle, the structure of the rear axle of the semi-trailer is relatively simple, mainly composed of axle body assembly, brake assembly, wheel end assembly, camshaft assembly and other components.

In terms of structure, the common rear axle of semi-trailer is mainly divided into the following types:

1. Drum axle

Drum axle is the most widely used rear axle of semi-trailer in the domestic market. Its main feature is the 360 ° sealed brake drum, which has large braking friction area, stronger and more sufficient braking force, and can be applied to all kinds of ordinary goods transportation.

Drum axle can be divided into American type and German type:

American axle is relatively affordable, simple in structure, and its accessories are common in the industry. It is easy to buy and match, and it is more convenient to repair and maintain. In design, it is more inclined to heavy load, with high cost performance, and is more suitable for the transportation of gravel, steel coil, wood, coal and other goods;

The advantages of the German axle are more lightweight and long-term. The weight is lighter than that of the American axle, which can save fuel. The design is resistant to high temperature, and the tire damage is small. The maintenance period has also been extended to a certain extent, which is more suitable for long-distance transportation with standard load.

When it comes to the maintenance period, I have to mention the maintenance-free axle.

The maintenance-free axle is also a kind of drum axle. It only changes the lubricating grease into lubricating oil to achieve long maintenance. The maintenance period can reach about 80W km at most. It is more suitable for the working conditions with high requirements for vehicle attendance and transportation efficiency, such as port suspension, logistics, green passage, cold chain transportation, etc., and of course the price is higher than that of ordinary axle.

2. Disc axle

In recent years, the application rate of disc axle on semi-trailer has become higher and higher. On the one hand, it is closely related to laws and regulations, on the other hand, it is also linked to its own characteristics.

The disc axle replaces the brake drum with a bare brake disc, which greatly improves the heat dissipation, heat attenuation resistance and water attenuation resistance. In addition, its brake transmission components have also been optimized. The brake pads can be driven immediately after the brake is pressed, and the brake response speed is fast. Especially when used with ABS, EBS, hydraulic retarder, air suspension and other devices, their respective advantages can be maximized, and together provide high-quality performance guarantee for the vehicle.

Generally, the disc axle is mainly used in dangerous goods transportation, precision instrument transportation, valuables transportation, flowers, fruits and vegetables transportation and other working conditions. Of course, the three-axle fence and the warehouse grid car that are clearly required by the regulations must also be equipped with disc brakes.

3. Low flat axle

The low flat axle is a special axle for the low flat semi-trailer, which is also known as the gooseneck truck. It is mainly used to transport large goods that cannot be disassembled.

Compared with the ordinary axle, the diameter of the wheel end of the low flat axle is small, which can provide a lower height from the ground to facilitate the loading and unloading of goods. At the same time, it also reduces the center of gravity of the vehicle and improves the stability. When the upper limit is high, it can also improve the passing ability of the vehicle to a greater extent.

In addition, the axle body and accessories of the low flat axle are special for heavy haul transportation, with higher wall thickness, higher strength, and stronger durability. The transportation machinery and equipment, large tanks, construction equipment, power station equipment, and so on are hardly mentioned.

4. Three-line six-axle axle

It is specially used for three-line six-axle semi-trailer, and is used for the transportation of large and oversized goods. In addition to three lines and six axes, four lines and eight axes, five lines and ten axes By analogy, they all belong to multi-axle heavy semi-trailer, and the applied axle also belongs to the rear axle of multi-axle semi-trailer.

The hub diameter of the three-wire six-axle axle axle is also relatively small, which is similar to the low flat axle axle, but the number of tires of the three-wire six-axle semi-trailer is more. A three-wire six-axle axle axle axle axle can be loaded with 12 sets of wheels, which can increase the contact area between the tires and the road surface, so as to reduce the average pressure of the wheels on the road surface and protect the road surface from damage. Therefore, the three-wire six-axle semi-trailer can bear 80t on the high speed, and the four-wire eight-axle semi-trailer can bear 80t on the high speed The load bearing tonnage of vehicles such as five-line and ten-axle vehicles is higher.

5. Concave axle

Also called eccentric axle, the most obvious feature is that its axle body and axle head are not in the same straight line, which is a bit like the overturned portal axle:

Such a design can reduce the chassis and center of gravity of the vehicle to a greater extent, improve the stability of the vehicle, expand the loading space of the cargo compartment, and provide convenience for the loading and unloading of goods, but at the same time, the requirements for road conditions are also further improved.

Concave axle is generally more used in car cars in China, and some trailers with requirements for vehicle chassis and center of gravity in foreign countries are also more used.