Patent ID: 8549853

Claim:
Hydraulic control device comprising a pressure source which can be switched on and switched off for supplying at least one consumer via at least one valve assembly with pressurised hydraulic medium, a reservoir, and a pressure switch arranged in a discharge path extending at least from the valve assembly to the reservoir , the pressure switch connecting the valve assembly via the discharge path with the reservoir when the pressure source is switched off, the pressure switch blocking the discharge path to the reservoir when the pressure source is switched on and builds up supply pressure, the pressure switch containing a movable control member which is actuable by a spring and a first pilot pressure originating from the pressure acting at the valve assembly in a first switching direction to a control position for opening the discharge path to the reservoir and by a second pilot pressure originating from the supply pressure in a second switching direction to a control position for blocking the discharge path, wherein the pressure switch is a 2/2-multi-way seat valve operating with a blocking position without leakage and containing a valve member forming the control member and a valve seat arranged in the discharge path, that the pressure source is permanently connected with the valve assembly via a restrictor contained in a main channel supplied with supply pressure from the pressure source, that the discharge path branches off from the main channel to the reservoir between the restrictor and the valve assembly, and that the second pilot pressure actuating the valve member in the second switching direction toward the valve seat originates from the supply pressure acting upstream of the restrictor in the main channel between the pressure source and the restrictor, and wherein the valve member is arranged in a stepped bore containing the valve seat, and having two stepped bore sections, that sideward channels of a sleeve extend to the stepped bore sections, the sleeve having outer axially distant annular sealing regions.