Suspension is the general name of all force transmission connecting devices between the vehicle frame and axle. After the vehicle is equipped with suspension, it can not only ensure the driving stability, but also help the vehicle deal with complex road conditions and achieve a certain balance between comfort and operating performance.

The suspension can be divided into independent suspension and non independent suspension. At present, the trailer suspension is mainly non independent suspension. Its structural feature is that the wheels on both sides are connected by an integral axle, and the wheels together with the axle are suspended under the frame or body through the suspension. It has the advantages of simple structure, low cost, high strength, easy maintenance and small change in front wheel positioning during driving.

1. Air Spring Dependent Suspension

Commonly known as "air suspension", it is mainly composed of compressor, air reservoir, height control valve, air spring, control rod, shock absorber, guide arm, lateral stabilizer, etc.

When the trailer is driving, due to the change of load and road surface, the suspension stiffness is required to change. Reduce the body height and increase the speed on the good road, and increase the body height and passing capacity on the bad road. The air spring non independent suspension can meet such requirements. As an elastic element, the air spring can alleviate the impact load from the road on the wheel when it is transmitted to the vehicle body through the axle. In addition, the air suspension can also realize the automatic adjustment of body height.

Air suspension can make the vehicle have a series of advantages, such as good ride comfort, single axle or multi axle lifting when needed, changing the body height and less damage to the road, but it also has the disadvantages of complex structure and strict sealing requirements.

2. Hydro pneumatic spring dependent suspension

Hydro pneumatic spring dependent suspension refers to the dependent suspension when the elastic element adopts hydro pneumatic spring. It is composed of hydro pneumatic spring, transverse thrust rod, buffer block, longitudinal thrust rod and other components.

Because the hydro pneumatic spring is installed between the frame and the axle, as an elastic element, it can alleviate the impact force from the road on the wheel when it is transmitted to the frame, and attenuate the subsequent vibration.

Hydro pneumatic suspension is suitable for commercial trucks with large loading capacity. Its volume and mass are smaller than leaf springs, but it has high sealing requirements and difficult maintenance.

3. Leaf spring dependent suspension

Leaf spring is used as the elastic element of non independent suspension, which is generally suitable for heavy-duty vehicles. Because it also acts as a guiding mechanism, the suspension system is greatly simplified. The utility model has the advantages of simple structure, low cost and reliable operation, but has the disadvantages of self weight and large layout space.

Although the three independent suspensions have their own advantages and disadvantages, from the industry trend in recent years, the air spring independent suspension has attracted more attention, especially in the transportation of high-end precision goods. Of course, it also depends on relevant policies and regulations to a certain extent. With the continuous improvement of production technology of domestic air suspension manufacturers, I believe its shortcomings will be overcome gradually.