Patent ID: 8701396

Claim:
A hydraulic system for an operator controlled machine, the system including at least one actuator for moving a machine component, a source of pressurized fluid for delivering pressurized fluid at a system pressure to a control valve which is operable under operator control, to control the flow of fluid from the source through the control valve to the actuator along at least a load pressure path defined between the control valve and the actuator, a flow control apparatus for controlling the system pressure and hence flow of fluid from the source through the control valve depending on the load pressure in the load pressure path, the flow control apparatus including an actuating part which is biased by a resilient device to a condition in which the flow control apparatus provides for a maximum flow of fluid to the control valve, actuating part movement by the resilient device being supported by fluid at a control pressure, the control pressure being derived from the load pressure in the load pressure path, and wherein the system includes a pressure control device to which the load pressure in the load pressure path is communicated, the pressure control device being operated under operator control either to deliver the control pressure to the flow control device at the load pressure in the load pressure path or a modified pressure which is less than the load pressure in the load pressure path.