Flow metering valve with operator selectable boosted flow

Claim 1

In a system (10) for supplying fluid flow to a hydraulic work circuit (12), the system (10) having a single pressurized fluid source (14) for supplying pressurized fluid thereto, control valve means (16) for controlling delivery of fluid flow from said source (14) to selectively drive the circuit (12) and flow control means (22) for metering a portion of the fluid flow to the hydraulic circuit (12), the improvement comprising: means (86) for controlling the magnitude of said portion in response to application thereto of a signal; operator controlled input means (78) for operator selectively applying said signal to said means (86) for operator selectively directly controlling the magnitude of said portion in direct response to a controlling action inititated by an operator; and wherein said flow control means (22) includes: a valve element (24) positionable in a first position and in a second position; means (70) for biasing said element (24) towards said first position thereof; means (25a, 25b) for allowing fluid flow to pass through said flow metering means (22) to said control valve means (16) in response to said element (24) being in said first position and for preventing said fluid flow in response to said element (24) being in said second position; means (40) for opposing said biasing means (70) with a force determined by a pressure of said portion intermediate said flow control means (22) and said control valve means (16); and means (76) for adding a force representative of the load to that of said biasing means (70) in response to a load experienced by said circuit (12); and wherein said signal applying means (78) adds a force to that of said biasing means (70), the added force being in response to selective operator input.