A pneumatic pressure control valve for a brake control system of a rail vehicle having at least three pressure chambers supplied with compressed air and are disposed in a housing of the pressure control valve, a first pressure chamber sealed by a piston and by a valve seat arranged on a tappet, subjected to a braking pressure and fluidically connected to a second pressure chamber via a conduit in the tappet to relieve pressure, a further third pressure chamber supplied with a supply pressure, arranged between the two pressure chambers and the sealing between the third pressure chamber and the second pressure chamber is achieved by a flat membrane arranged in the third pressure chamber and which enables the tappet to be axially displaced, the flat membrane has a circular opening arranged substantially centrally to provide a check function and through which the tappet extends in the axial direction.