Abstract: A hydraulic valve in a load responsive pressure flow compensated system for operating a header height cylinder including a lockout check valve which is opened by an accompanying plunger experiencing pressure in an adjacent motor port. Said plunger includes a metering notch opening to drain when the plunger is actuated, said metering notch is sized larger than the flow-sensing notch on the valve spool so that while lowering the machine header, the pressure compensating means of the system does not go to full pressure compensation level but rather stands by at the low pressure level relieved across the lockout actuating plunger. The valve further includes metering notches in the control valve spool which are so shaped that a FLOW vs. TIME curve of the spool from the neutral position to an operating position has a plateau at a time interval from zero which is substantially equal to one-half of the cycle time of the natural frequency of the machine.

Abstract: A hydraulic control valve in a closed-center load responsive system having a passage with a check valve therein downstream of the inlet metering and signal passage allowing flow from the signal passage to the load prior to connecting the pressure circuit to the load circuit so as to relieve fluid from the signal circuit to the load circuit as the signal circuit attains a pressure higher than the existing load thus causing flow past the inlet metering whereby the pressure differential in the metering compensates the pump.