| 摘要 |
A hydraulic system (10) for an operator controlled machine (M), the system (10) including at least one actuator (12) for moving a machine component (W1), a source (14) of pressurised fluid for delivering pressurised fluid at a system pressure to a control valve (16) which is operable under operator control, to control the flow of fluid from the source (14) to the actuator (12) at a load pressure, along a load pressure path (38), a flow control apparatus (20) for controlling the flow of fluid from the source (14) to the control valve (16), the flow control apparatus including an actuating part (50) which is biased by a resilient device (24) to a condition in which the flow control apparatus (20) provides for a maximum flow of fluid to the control valve (16), actuating part (50) movement by the resilient device (24) being resisted by system pressure fluid and being supported by fluid at a control pressure, the control pressure being derived from the load pressure, and wherein the system (10) includes a pressure control device (30) to which the load pressure is communicated, the pressure control device (30) being operated under operator control either to deliver the control pressure to the flow control device (20) at load pressure or a modified pressure which is less than the load pressure.
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