Patent ID: 8920104

Claim:
A mining shovel comprising: a crawler truck; a turntable mounted to the crawler truck; an A-frame mounted to the turntable; a hydraulic power unit mounted to the turntable and including a pump and a return tank for hydraulic fluid; a boom extending from the turntable and having an upper end supported by the A-frame, and including a sheave coupled to a distal upper end of the boom; a dipper handle including a dipper at a distal end pivotally supported by the boom, to pivot the dipper in a vertical plane; a hoist cable extends over the sheave at the top of the boom and to the dipper, for vertically raising and lowering the dipper; and a crowd mechanism including a double acting hydraulic cylinder for extending and retracting the dipper handle horizontally, wherein a cylinder control manifold is coupled to the double acting hydraulic cylinder in fluid communications with the pump and the return tank, the cylinder control manifold driving the double acting hydraulic cylinder to extend and retract the crowd mechanism, wherein the cylinder control manifold directs fluid flow in a single direction from the pump to the return tank such that fluid flows in a single direction through a supply conduit for providing a supply from the pump to the cylinder actuator and through a return conduit for providing a path to the return tank, wherein the supply conduit has a smaller diameter than the return conduit such that the single direction fluid flow has a higher pressure when entering the cylinder actuator than when returning to the return tank.