Firestone Number: W01-M58-8705
Firestone Number: W01 M58 8705
Firestone Number: W01M588705
Firestone Bellows Number: 1T17AR-4.5
Contitech Number: 836MBK4
Contitech Number: 836 MB K4
Phoenix Number: 1 DF 25-14
| Granning | 17060 | Airtech | 131922 |
| Airtech | 3836-04K | Meritor | MLF7056 |
| VDL BUS | 0377498 | DAF | 0377498 |
How does the air spring of a truck suspension work?
The air spring in a truck suspension is a device that uses
compressed air as an elastic medium, which replaces or assists
traditional leaf springs or coil springs.
1. Supporting load: When the truck is stationary or driving on a
flat road, the airbag is filled with compressed air of a certain
pressure. The airbag expands and forms a supporting force between
the frame (upper cover) and the axle (piston). This supporting
force balances the weight of the truck (including its own weight
and load).
2. Absorbing shock: When the wheel encounters a bump (such as a
bump on the road), the wheel moves upward, pushing the axle closer
to the frame and compressing the airbag.
3. The airbag is compressed, the air inside is compressed, and the
pressure increases. The compressed air generates a strong reaction
force (elastic force) to resist compression, absorb impact energy,
and slow down the impact force transmitted to the frame.
4. Rebound: When the wheel encounters a depression (such as a
pothole on the road), the wheel moves downward, the axle moves away
from the frame, and the airbag is stretched. The airbag stretches,
the volume of the air inside increases, and the pressure decreases.
The elasticity of the airbag itself (rubber and cord) and the
reduced pressure make it produce a rebound force, trying to restore
its original shape, pull the axle to prevent excessive falling, and
keep the tire in contact with the road.
5. Automatic height adjustment:
Load increase: When the truck is loaded with cargo, the weight
increases, the airbag is compressed, and the vehicle height
decreases. The height sensor detects that the height is lower than
the preset target value.
Inflation: The ECU receives a signal and opens the inflation
solenoid valve. Compressed air from the air tank enters the airbag
through the pipeline.
Pressure increase & height recovery: The amount of air in the
airbag increases, the pressure increases, and the airbag expands to
lift the vehicle body until the preset driving height is restored.
Load reduction: When the weight is reduced after unloading, the
airbag over-inflates and the vehicle height increases. The height
sensor detects that the height is higher than the target value.
Deflation: The ECU opens the deflation solenoid valve. Part of the
compressed air in the airbag is released into the atmosphere.
Pressure reduction & height recovery: The amount of air in the
airbag decreases, the pressure decreases, the airbag shrinks, the
vehicle height drops, and the preset height is restored.
6. Damping (usually requires shock absorbers): The air spring
itself mainly provides elastic support and height adjustment, but
cannot effectively attenuate vibration (the valve for air in and
out of the airbag is too small, and the damping effect is limited).
Therefore, the truck air suspension system must be equipped with
traditional hydraulic shock absorbers. The shock absorber is
responsible for quickly absorbing and dissipating the kinetic
energy generated during the compression and rebound of the airbag,
preventing the vehicle body from continuously jumping up and down,
and ensuring driving smoothness and stability.
