Air supply unit for a vehicle

An air-supply unit has a compressor (1) driven by a motor (2), a sound absorber (3) with one or more rubber tubes and an air-dryer (4) and supplies pneumatic springs (5) with air. The pneumatic springs each connect in series to valves (6) able to trigger individual pneumatic springs. The unit has other valves (7,8) and a return valve (9) operated electromagnetically and controlled by an electronic control unit (10).