Shanghai Komman Vehicle Component Systems Stock Co., Ltd.
Shanghai Komman Vehicle Component Systems Stock Co., Ltd.

Precautions and troubleshooting measures for semi-trailer air suspension

Jul 20 , 2023

Air suspension is a suspension system used in buses and heavy-duty trucks, is the world trend of steel springs. At present, 95% of the buses, 80% of the trucks and 40% of the trailers in Europe and the United States have used air suspension system. So, what are the advantages of semi-trailer air suspension? And what are the common failures? Today we will give you an introduction!

The advantages of semi-trailer air suspension

Light weight

The biggest advantage of air suspension is light weight, much lighter than the traditional steel spring suspension.

Easy to load and unload

Through the manual height valve in the air suspension system, the height of the vehicle loading platform can be adjusted within a certain range to facilitate the loading and unloading of goods.

Smooth driving and good vibration damping performance. Compared with light weight vehicles, the vehicle with air suspension is more smooth to drive.

High safety

Each axle axle load distribution and tire and ground contact balance, can improve the overall braking performance of the axle and cornering stability. At the same time, the height of the air spring can be automatically adjusted according to the road conditions to reduce vibration, which is conducive to the protection of cargo safety.

Reduce maintenance cost

When the vehicle is running empty, the semi trailer air suspension can lift the axle, reduce tire wear and tear, extend service life, and reduce fuel consumption.

Common faults of semi-trailer air suspension

The most common fault of air suspension is airbag without air or airbag wrinkles, the causes of these two situations are different, and the treatment methods are also different, and should be treated differently when actually encountered.

No air bag of air suspension

This situation is relatively simple to check, as long as we understand the air suspension air circuit structure, we can start from where to start. The air source of the air suspension is picked up by the brake system, after the pressure protection valve, stored in a special storage cylinder. When working through the filter to the core components of the air suspension - height control valve, and then to the left and right airbags.

Semi-trailer air suspension of the airbag without air causes

  • No air or very low pressure in the air suspension special storage cylinder, in order to ensure that the brake system has sufficient pressure, when the trailer air pressure is lower than 0.6MPA, the pressure protection valve will suspend the air supply to the air suspension storage cylinder.

  • The air line is clogged or folded, and no air is passed.

  • The height control valve connecting rod comes off.

  • The height control valve is damaged.

Solutions for air suspension's air bag without air

  • Adjust and replace the bent or clogged air line.

  • Adjust and install the height control valve connecting rod.

  • Replace the height control valve.

Air bag of semi-trailer air suspension has air, but the air bag is wrinkled

The reason of air bag wrinkling may be

  • When the vehicle is transferred and lifted, the airbag is stretched out more and not reset properly, resulting in the airbag wrinkling.

  • When the vehicle goes in and out of the maintenance workshop or larger slope platform, it may also lead to individual airbag being over-stretched, causing airbag wrinkling.

Solution for airbag wrinkling

Remove the connection between the rubber connector under the vertical rod of the height control valve and the axle, lift the rod upward, wait for all the airbags to have enough air, then put the rod back in, and the airbags can return to the normal state. In addition, if this kind of failure occurs frequently during the driving process, we should consider increasing the limiting device between the axle and the frame.

Vehicle problems caused by the failure of semi-trailer air suspension

Air bag wrinkles cause tractor and semi-trailer braking is not synchronized, and then lead to vehicle braking jumping.

Vehicle braking jumping appears the cause of the failure

Vehicle parking or reverse braking, due to the inertia factor of the vehicle, in the brake braking moment, the vehicle tail will be stretched upward, and at the same time handbrake braking, the vehicle tail will not be able to fall back, the height of the control valve is in the exhaust state, air bag air pressure will be evacuated, when the brake is released again, the whole vehicle will instantly fall or lead to air bag crease.


Park or reverse the vehicle slowly and then pull the handbrake, the above situation will not occur.

If the airbag is wrinkled, loosen the connecting bolt between the height control valve and the axle, fully inflate the airbag and then put the connecting rod back according to the original position.

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