Valve arrangement

A valve arrangement comprising a housing, electromagnetically actuatable preliminary control valve means for controlling a differential pressure in said housing, a main valve in said housing, said main valve actuable by the differential pressure, said main valve including a closing element for selectively connecting an outlet connection and at least one inlet connection, wherein said main valve is connected to a movable wall and is exposed to a balanced pressure thereacross in a rest condition, said wall being pressurizable by the differential pressure to change over said main valve, wherein said housing of the valve arrangement is subdivided into a valve housing, a vacuum housing and a control housing, wherein said movable wall is arranged in a cavity which is located between said vacuum housing and said control housing, said movable wall subdividing said cavity into a vacuum chamber and a ventable power chamber, wherein said movable wall is formed by a diaphragm which is inserted in said housing between said vacuum housing and said control housing and by a diaphragm dish which is pre-tensioned by a return spring and which is engaged by a main valve actuating tappet, wherein said tappet is guided within said vacuum housing and is provided with a first valve disk at which a first sealing seat of said main valve is located, wherein said first sealing seat is arranged coaxially with a second sealing seat provided in said valve housing, said first sealing seat contacted by said closing element of said main valve in the rest position, wherein said valve element is retained in said valve housing between a holder attached to said valve housing and a retaining ring in said housing, said retaining ring being sealed off from said valve housing by an O-ring between said retaining ring and said housing.