(57) Avalve for automatically directing the flow of fluid from a source of pressure to
each side in turn of a double acting hydraulic actuator causing it to reciprocate.
The valve assembly comprising a valve spool (12) which is acted on by a return spring
(13) to urge the valve spool into a starting position, in which position fluid flows
to one side of the actuator. Spring loaded valve means (17,25) controls the flow of
fluid, when a predetermined pressure is exceeded, to a pilot spool (14) which acts
on the valve spool to change over its position. The valve spool (12) is held in the
change over position by a back pressure which is generated during the return of the
actuator by the flow of fluid through a throttle (D) formed between the valve spool
and the pilot spool.
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