Variable-displacement pump 1 delivers fluid from one end of power cylinder 2 to the other and back again. Compensating pump 3 provides make-up fluid through check valves 4 to compensate for leakage. Relief valve 5 sets up a constant pressure in the delivery line of pump 3. Relief valves 6 prevent excess pressure in the delivery line of pump 1. When lever 8 is turned, valve spool 7 is shifted and fluid from pump 3 is delivered to servomotor 9, moving its piston and changing the output of pump 1. Upon motion of the piston of servomotor 9, spool 7 returns to its initial position.
$4180$CHP,Dr$