Luftbalg

An air spring (bellows) is a rubber air-filled cushion that supports the vehicle on an air suspension.

Compressed air inside carries the load, and adjusting the pressure keeps the ride height constant whether loaded or empty, giving a smooth ride.

Air springs are fitted at the axles of air-suspended trucks, trailers, and cabs. Because they affect stability and ride height, faulty bellows should be replaced by a qualified technician.