Several height control valves are suspended by freight car airbags.

Two height control valves are hung on the airbag of the truck. The first height valve is installed on the rear axle, which controls the air intake or exhaust of the air spring (airbag) of the rear axle by sensing the height change of the rear of the vehicle, so as to adjust the height of the air spring (airbag) of the rear axle in time, ensure the stability of the vehicle under different road conditions, improve the driving comfort, and prevent the road surface from being damaged by the impact of wheels. The second height valve is installed on the frame, and controls the air intake or exhaust of the front axle air spring (airbag) by sensing the height change of the front part of the vehicle, so as to adjust the height of the front axle air spring (airbag) in time.