Variable-displacement reversible pump 1 delivers fluid from one end of power cylinder 2 to the other and back again. Pump 3 serves to compensate for leakage in the circuit. When the pressure drops due to leakage, valve 4 opens, admitting fluid from compensating pump 3 into the suction line of pump 1. Relief valve 5 maintains constant pressure in the delivery line of compensating pump 3. Valves 6 prevent excess pressure in the delivery line of pump 1.
$4177$CHP,Dr$