Variable-displacement pump 1 draws in fluid from the left end of power cylinder 2 and delivers it to the right end, to which fluid is also delivered by high-pressure compensating pump 3, thereby compensating for leakage in the system. Differential valve spool 4 is subject to the pressure of the delivery line and the suction line on one side, and to the action of spring 5 on the other side. Upon an increase in pressure in the system, spool 4 is shifted to the right, by-passing surplus fluid to the tank.
$4178$CHP,Dr$