| 摘要 |
A control valve operating as a combined relief and make-up valve for use in hydraulic apparatus comprises a valve housing provided with a blind hole, a valve seat tightly engaged with the inlet of the blind hole, a cylindrical hollow make-up poppet slidably inserted into the blind hole, a cylindrical relief poppet slidably inserted within the make-up poppet, a screw member adjustably engaged with the inner surface of the end of the make-up poppet, a coil spring disposed between the screw member and the relief poppet, and a balance piston having one end tightly inserted into the inner cylindrical hole of the relief poppet. The valve housing is provided with a first opening connected to an external hydraulic supply device and a second opening connected to a hydraulic source. The first and second openings are communicated with each other in response to differential pressure of an operating fluid so as to operate the control valve as a relief valve or a make-up valve.
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