Patent ID: 7401623

Claim:
A valve unit for a hydraulic system, the valve unit comprising: a hollow housing having a first end for communicating with a reservoir and a second end for communicating with a pump; a housing valve land member between the first and second ends; a valve member movably mounted in the housing, the valve member having a central position wherein the valve member is received by the land member thereby restricting fluid flow therebetween; a valve spring biased to urge the valve member away from the first end of the housing, the valve member, in response to fluid pressure, being movable out of said central position to displaced positions on opposite sides of the land member; a hollow sleeve projecting from the housing, the sleeve forming a larger diameter bore and a smaller diameter bore separated by an annular shoulder, the spring being received by the larger diameter bore; and a stop disk mounted in the larger diameter bore between the spring and the shoulder, the stop disk being engagable with a valve stem which projects from the valve member.