| 摘要 |
A valve assembly including a housing having an elongated bore formed therein. Inlet, outlet, and load ports communicate with the bore. A valve is positioned within the bore for controlling flow of a pressure fluid between the ports. A seal ring is mounted on the valve and disposed in sealing engagement with the housing in the vicinity of the inlet port. The seal ring is axially shiftable across the inlet port in response to shifting movement of the valve. The seal ring is mounted in an annular groove which encircles the valve and has an axial width substantially greater than the axial width of the seal ring. The seal ring is shifted axially relative to the groove by the pressure fluid supplied through the inlet port when the valve is shifted between first and second operational positions. A fluid-assisted spring means coacts between the valve and the housing, which spring means includes a spring-confining chamber defined between one end of the valve and the adjacent portion of the housing. A passage extends interiorly of the valve for providing fluid communication between the chamber and the inlet port. The passage terminates in a hole which opens through the bottom of the groove. The seal ring is movable over the hole during shifting of the valve between the first and second operational positions.
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