Abstract: A hydraulic control valve has a spool slidably received in a bore of the valve body. The spool can be moved in opposite directions to control flow fluid to and from a pair of workports. A sensor assembly has a coupling attached to the spool and holds a permanent magnet. A Hall effect sensor produces an electrical signal indicating the position of the permanent magnet and thus the spool. A double acting spring assembly biases the coupling and spool with respect to the housing of the sensor when the spool moves in one direction, and biases the coupling and spool with respect to the valve body when the spool moves in the other direction.

Abstract: An improved pressure-compensated hydraulic system includes a separate valve section which feeds hydraulic fluid from a variable displacement pump to one of several hydraulic actuators. Each valve section has a main valve spool and a pressure compensating poppet. The main valve spool has a metering orifice that controls the flow of fluid to the actuator. The poppets in the valve sections collectively apply a pressure to the pump pressure control input which is a function of the greatest to a load pressure among the hydraulic actuators.

Abstract: A pilot operated control valve has a main poppet which selectively engages a valve seat to control flow of fluid between an inlet and an outlet. The flow of fluid through a pilot passage in the main poppet is controlled by a pilot poppet that has a pressure balancing stem extending into the pilot passage. The control valve incorporates a compression check valve and/or a reverse flow check valve, in addition to a transducer for sensing the pressure at the outlet.

Abstract: An improved pressure-compensated hydraulic system for feeding hydraulic fluid from a variable displacement pump to multiple hydraulic actuators. A separate valve section controls the fluid flow between the pump and a different actuator. Each valve section has a pressure compensating valve with a valve member and poppet within a bore and biased apart by a spring. The poppet acts as a check valve which prevents fluid flow from the actuator through the valve section to the pump when the back pressure from the load exceeds the pump supply pressure. A pressure differential between the load-dependent pressure and the actuator pressure determines a position of the valve member which controls the pressure applied to the pump pressure control input.

Abstract: A pilot operated control valve has a housing defining an inlet and an outlet. A main valve poppet selectively engages a valve seat to control flow of fluid between the inlet and outlet. An aperture in the main valve poppet opens into a control chamber on a side of the main poppet remote from the valve seat. A pilot passage is formed in the main valve poppet with an inlet section between the inlet and the control chamber, and an outlet section between the aperture and the control chamber. A pilot poppet has a body that selectively seals communication between the control chamber and the aperture, and a pressure balancing stem attached to the body extends into the aperture. The pressure balancing stem having a recess which is acted upon by pressure in the outlet section and having an end which is acted upon by pressure in the inlet section. The pilot operated control valve also incorporates a compression check valve and/or a reverse flow check valve.

Abstract: An improved pressure-compensated hydraulic system for feeding hydraulic fluid to one or more hydraulic actuators. A remotely located, variable displacement pump provides an output pressure equal to a control input pressure plus a constant margin. A pressure compensation system requires that a load-dependent pressure be provided to the pump input through a load sense circuit. An isolator transmits the load-dependent pressure to the pump control input, while preventing fluid from leaving the load sense circuit and flowing to the remotely located pump. A valve section, which controls the fluid flow between the pump and actuator, has a pressure compensating valve with a piston and spool controlling a pressure differential across a main control valve orifice by moving within a bore in response to a pressure differential between a pump supply pressure and the load sense pressure.

Abstract: An improved pressure-compensated hydraulic system for feeding hydraulic fluid to one or more hydraulic actuators. A remotely located, variable displacement pump provides an output pressure equal to input pressure plus a constant margin. A pressure compensation systems requires that a load-dependent pressure be provided to the pump input through a load sense circuit. A reciprocally spooled, multi-ported isolator transmits the load-dependent pressure to the pump input but prevents fluid in the load sense circuit from leaving the load sense circuit and flowing through a relatively long conduit leading to the remotely located pump. In a multi-valve array, at least one valve section has a backflow-preventing shuttle valve which prevents backflow through the pressure compensation system if a main relief valve is operative.

Abstract: A control valve (10) is provided for mobile or stationary hydraulic equipment for automatically increasing or decreasing speed of a prime mover in response to operation of a hand lever to extend a hydraulic cylinder. A prime mover speed control valve (42) is integrated with a spool (12) in a single housing (10) for the purpose of simultaneously controlling the supply of fluid to a hydraulic cylinder (16) and to a cylinder (61) controlling prime mover speed. When the spool (12) is in the "CYLINDER EXTEND" or "NEUTRAL" position for the implement cylinder, a hydraulic control signal is provided from port (55) to the prime mover control cylinder (61) to signal increased prime mover speed and increased output from a hydraulic pump (17). When the spool (12) is in the "CYLINDER RETRACT" position for the implement cylinder (16), the spool (12) blocks the signal from port (55) while allowing fluid to drain from the implement cylinder (16) to a reservoir (29).

Abstract: A semi-active vehicle suspension system employing a shock absorber whose damping characteristics are variable under the control of a signal representing one or more conditions of the vehicle. The system employs a coaxially arranged valve pair to provide one or two fluid flow paths between a chamber of the shock absorber and a reservoir. Two of such coaxial valve pairs may be used in tandem to control both chambers of the shock absorber in an inverse relationship. Both of the tandem pairs may be controlled by a single spool which is controlled by a single control signal.

Abstract: An improved pressure-compensated hydraulic system for feeding hydraulic fluid to one or more hydraulic actuators. A remotely located, variable displacement pump provides an output pressure equal to input pressure plus a constant margin. A pressure compensation systems requires that a load-dependent pressure be provided to the pump input through a load sense circuit. A reciprocally spooled, multiported isolator transmits the load-dependent pressure to the pump input but prevents fluid in the load sense circuit from leaving the load sense circuit and flowing through a relatively long conduit leading to the remotely located pump. In a multi-valve array, at least one valve section has a backflow-preventing shuttle valve which prevents backflow through the pressure compensation system if a main relief valve is operative.

Abstract: A hydraulic fluid-loss control valve for preventing uncontrolled load movement in the event of a fluid loss such as from the bursting of a hose and further for allowing an operator to move the load in a controlled way despite the fluid loss. The control valve is situated between a conventional main spool valve and a piston/cylinder hydraulic actuator which powers the load. The control valve has a spool sliding reciprocally in a bore. Grooves and lands on the spool combine with passages in the control valve body to provide alternate fluid paths between a pump and the actuator and between the actuator and a reservoir. Fluid can flow from a controlled chamber of the actuator only when the spool is in a position which provides a fluid path. A passage within the spool provides fluid communication between an input fluid flow and a chamber at one end of the spool. A second passage within the spool provides fluid communication between an actuator chamber and a chamber at the other end of the spool.

Abstract: A pressure compensated hydraulic valve (2) is provided with a housing (4) having a reciprocal spool (6) for communicating hydraulic fluid to work ports (8,10). Pressure compensating means (58) is provided in the same housing with the valve and senses work port pressure by hydraulic fluid flow through the spool from the work port and creates a substantially fixed differential pressure across the spool by controlling the pressure after the flow has passed through the spool.

Abstract: A manual override handle assembly for the operation of a hydraulic control valve of the type having a movable spool includes a housing forming a hollow chamber in which a spool extension is slidably mounted. A handle assembly extends outwardly from the housing and is mounted for pivotal movement within the chamber. The handle is movable to an inoperable position wherein the handle is disassociated from the spool extension so that movement of the spool extension will not result in movement of the handle. The handle is further movable to an operable position wherein the handle engages the spool extension so that movement of the handle results in movement of the spool extension.

Abstract: A cross line relief valve mechanism includes a pair of opposed relief valves contained in a bore connecting the service passages of a control valve. A high pressure condition in one of the service passages acts directly on the main poppet of one of the relief valves causing it to become unseated and communicating the high pressure condition to a zone in the bore between the two relief valves. The high pressure condition in this zone acts on the pilot poppet of the other relief valve causing it to open which results in the unseating of the main poppet in that relief valve. The high pressure condition in one of the service passages thus results in the opening of both valves so as to allow high pressure fluid to flow from one service passage to the other in order to obtain a balanced condition.

Abstract: A hydraulic sectional control valve includes separate pump pressure and function control spools. The spools may be actuated independently and sequentially to provide raising, holding and power down functions for earthmoving and construction vehicles. Additional function control spools may be added in the valve structure to provide multiple function control.

Abstract: A control valve having a pair of service passages for connection with the opposite sides of a reversible fluid motor, wherein a flow control valve for each service passage restricts exhaust flow therethrough to prevent the pressure thereof from exceeding a predetermined value, but in no way influences flow to a fluid motor of supply pressure fluid from its service passage. Flow coordinating means limits flow of supply fluid to each service passage substantially in correspondence with restricted flow of motor exhaust fluid in the other service passage.

Abstract: The present invention pertains to detent mechanisms for use with valve spools wherein the detent mechanisms are operable to releaseably secure the valve spool in various predetermined axial positions and to apply various biasing forces on the valve spool depending upon its axial position thereby permitting the valve operator to sense or feel the position of the valve spool. The detent mechanism of the invention includes a generally cylindrical housing which supports a pair of spaced magnets and which receives a shaft coaxial with and connected to the valve spool. The shaft is received through bores in the magnets and is slideable with respect to the magnets. The shaft also supports a pair of contact rings which are comprised of magnetically attractable material and which are received in the space between the magnets. Upon axial movement of the valve spool, the contact rings are brought into contact with one of the magnets.

Abstract: A control valve having a pair of service passages for connection with the opposite sides of a reversible fluid motor, wherein a flow control valve for each service passage restricts exhaust flow therethrough to prevent the pressure thereof from exceeding a predetermined value, but in no way influences flow to a fluid motor of supply pressure fluid from its service passage. Flow coordinating means limits flow of supply fluid to each service passage substantially in correspondence with restricted flow of motor exhaust fluid in the other service passage.