Dual Pump draft control valve
AssigneeAllis-Chalmers Corporation
InventorJohn R. Plate
Life of this patent
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Abstract
A draft control valve for use with two constant displacement pumps in an open center hydraulic system. The valve controls the implement position in response to the draft loads and manual control and normally employs pressurized fluid from a low volume pump for operating in response to draft load sensing for control the implement position and employs pressurized fluid from the high volume pump for relatively short periods of time for positioning of the implement in response by the operator and extreme draft loads.
Claims10
A draft control valve for use on a vehicle comprising, a valve housing defining a central opening interconnecting a low volume pump chamber, a high volume pump chamber, a hydraulic actuator chamber, and a sump chamber, hydraulic actuator passage means for connecting said hydraulic actuator chamber to a hydraulic actuator, a valve member received in said central opening for selectively alternately directing fluid flow from said pump chambers to said hydraulic actuator chamber and connecting said hydraulic actuator chamber to said sump chamber, a flow restrictor for restricting fluid flow from said hydraulic actuator passage means to said sump chamber, said valve member and said valve housing defining passage means and a variable orifice means connected in parallel for controlling the flow of fluid between said high volume pump chamber and sump chamber responsive to movement of said valve member, draft load control and manual control means selectively positioning said valve member for operation of said valve.
Dependencies are inferred from the claim text.