A compressed air supply installation for operating a pneumatic installation, especially an air suspension installation of a vehicle, includes a compressed air supply unit, a compressed air port towards the pneumatic installation, a venting port towards the surroundings, a first pneumatic connection between the compressed air supply and the compressed air port, the first pneumatic connection having an air drier and a shut-off valve, and a second pneumatic connection between the compressed air port and the venting port. The shut-off valve is a pneumatically pilot-controlled check valve.

A valve (18), for a valve assembly (10) for regulating the pressure of a fluid guided in a hydraulic system for supplying pressure to at least one hydraulic consumer (12a, 12b), includes a pilot control stage (48) and a main control stage (38) for at least partially clearing or blocking a fluid path from a supply connection (P) to an outflow connection (T). A relief stage (54) for pressure relief of a fluid chamber is arranged between the pilot control stage (48) and the main control stage (38). The relief stage (54) compares the existing load pressure at load terminal (LS) dedicated to the hydraulic consumer (12a, 12b) with the outflow pressure at the outflow connection (T), clearing the pressure relief if both pressures are approximately the same. The relief stage (54) can be directly connected to the load connection (LS) and can be charged with load pressure.