| 摘要 |
PCT No. PCT/EP95/04454 Sec. 371 Date Sep. 16, 1997 Sec. 102(e) Date Sep. 16, 1997 PCT Filed Nov. 13, 1995 PCT Pub. No. WO96/15373 PCT Pub. Date May 23, 1996A pilot controlled servo-valve has four main flow connections, an axially sliding main control piston with four control edges and a front restoring spring that defines a spring-centered middle position of the main control piston. A control sleeve has ring shaped openings for the first, second and third main flow connections and a front opening for the fourth main flow connection. A first front face of the main control piston is axially opposed to the front opening. A pressure compensation surface is formed by the second front face of the main control piston in a spring chamber. The main control piston applies the pressure in the fourth main flow connection on said pressure compensating surface through a pressure relief channel. A traverse bore connects said pressure relief channel to an auxiliary connection chamber connected to the third main flow connection by the forth control edge. This valve may be space-savingly integrated in a hydraulic block and has a clearly defined middle position, as well as a remarkable dynamic performance.
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