When pilot valve spool 1 is shifted to the right, fluid is delivered from the valve to the left end of main valve spool 2, shifting it also to the right. At this, fluid is delivered by gear pump 3 through a groove of spool 2 to the right end of power cylinder 4, moving its piston to the left. When pilot valve spool 1 is shifted to the left, spool 2 is also shifted by pilot fluid to the left, admitting fluid delivered by pump 3 to the left end of cylinder 4. In the central position of spool 1, main valve spool 2 is centered by springs 5.
$4219$CHP,Dr$