摘要 |
A high frequency four-way valve reciprocated by hydromechanical amplifiers has its amplifier volumes volume compensated by passage means in each valve spool end connecting each amplifier volume with the adjacent outlet port. In a modification, there are longitudinally extending grooves on the outer periphery of each drive piston, one group of longitudinal grooves connecting the amplifier volume with the annular lubrication grooves around the piston and another group of longitudinal grooves connecting the annular grooves with the adjacent outlet port. The longitudinal grooves supply lubricant to the annular grooves, and also enhance the volume compensation.
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