The Cessna Aircraft Company

Alan D Jackson

Homer R Graber

Frank N Alexander

Dennis J Stucky

Robert D Krehbiel

Kenneth E Day

A metering lockout check valve which lowers gravity loads without chatter. The poppet has a conical concave face which surrounds an annular seat and is shaped so that as the poppet opens, the effective closing force increases requiring higher pressures in the opposite motor port to open the poppet. Conversely an overrun condition is prevented since when the pressure drops in the pump pressure side of the circuit, the poppet will reduce its opening and provide a metering function.

Metered lockout valve

A meter-out load sensing hydraulic system controlling one or more motors, supplied by a variable displacement pump through a directional control valve. The compensating means of the pump senses pressure and flow on the discharge or return side of the motor to determine the pump cam plate position. The signal line connecting this discharge side of the motor to the compensating means is also supplied with a low pressure signal flow which causes the pump to standby at a low pressure level in a neutral valve position or when metering down a gravity load.

Outlet metering load-sensing circuit

A relief valve with a low hysteresis closing curve with a fixed seat and a spring-biased poppet which is guided for longitudinal movement by an axial guide sleeve and aligns with its seat by pivoting about a fixed point through a small angle of rotation.

Reseat relief valve

The invention is an improved pressure compensating flow limiting valve which maintains an optimum performance curve at differing flow rates. The invention is the specific placing of a vent passage in the valve spool immediately downstream of the fluid jet passing across the spool in a metering mode with the vent passage connected to one of the servo chambers which positions the spool. The effect of the exiting fluid jet draws some fluid from the vent passage thereby dropping the pressure level in that servo chamber sufficiently to offset certain dynamic forces on the spool and balance the spring forces on the spool with these forces regardless of the flow rate through the valve.

Flow limiting valve

A removable plug used for setting land timming of a control valve spool or spring loading in relief valves. The plug has deflectable contact points which deform in its plastic range against the harder surface of the valve body as the plug is screwed into the valve body to position the spool for precise and repeatable land timming.

Deformable plug

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.

Header height valve

This invention is a specific method for shaping the shank of a hydraulic control valve spool to alter the momentum exchange from high pressure fluid flowing across the spool so as to balance the various dynamic forces acting on the spool. The shank is shaped to turn the high velocity stream away from the spool at a lesser angle than the entry angle of the stream while utilizing conventional square-edge lands.

Momentum balance spool

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.

Growing community of inventors

Hutchinson, KS, United States of America

Alan D Jackson