In the position of pilot valve spool 2 shown, fluid from gear pump 1 is delivered partly through the body of the pilot valve to the left end of main valve spool 3, shifting the spool to the right. The main part of the fluid delivered by pump 1 is directed by a groove of spool 3 to the right end of power cylinder 4, moving its piston to the left. When pilot valve spool 2 is shifted to the left, spool 3 is also shifted by pilot fluid to the left, and fluid from pump 1 is delivered to the left end of cylinder 4. Thus, pilot valve spool 2 serves to control spool 3 of the pilot-operated main valve.
$4220$CHP,Dr$