| 摘要 |
<p>A four-way spool-type valve assembly for controlling the actuation of a double-acting fluid motor characterized in that the spool has therewithin a relief valve and a check valve respectively operative to build up back pressure in the return line from the motor during the load lowering operation and to permit return flow under such back pressure into the inlet port to prevent cavitation of the fluid motor. The spool herein is further characterized in that in the load raising position thereof both the relief valve and the check valve are bypassed so as to offer minimum restriction to fluid flow into and from the fluid motor.</p> |
