Gear pump 1 delivers fluid to the rod end of cylinder 2 and to the suction chamber of variable-displacement rotary piston pump 3. Valve member 4 is subject on top to the pressure developed by piston pump 3 and below to the pressure developed by gear pump 1. S ince the top and bottom cross-sectional areas of valve member 4 are equal, the discharge and suction chambers of pump 3 are at the same pressure, and this eliminates leakage from one chamber to the other. Surplus fluid delivered by pump 1 drains back to the tank through relief valve 6. Relief valve 5 protects the system against overloads.
$4142$CHP,Dr$