Abstract: A direction flow control valve responsive to a manual control signal for control of positive and negative loads operated by a single pilot valve stage, which automatically maintains a relatively constant pressure differential across valve spool, while controlling positive and negative loads and which permits independent adjustment in maximum flow level through the valve for positive and negative load control.

Abstract: An electro-hydraulic proportional control valve includes an electro-hydraulic pilot valve, an inlet pressure reducing valve, and a directional control valve. The electro-hydraulic pilot valve receives an electrical input signal and provides a hydraulic signal to the directional control valve in response to the electrical signal. The inlet pressure reducing valve modulates fluid flow from a pump to the directional control valve to maintain a constant pressure drop across the directional control valve under all conditions. The directional control valve includes a directional control valve spool which shifts between a neutral position, a leftward displaced position, and a rightward displaced position in response to the hydraulic signal from the electro-hydraulic pilot valve. The directional control valve spool includes a range adjustment device for adjusting and setting the flow rate through the directional control valve.

Abstract: An hydraulic system: a power assisted vehicle steering system which includes such an hydraulic system and a method of alleviating noise in an hydraulic system. The hydraulic system as applied to a vehicle steering gear (1) has an open center valve (3) which directs hydraulic fluid under pressure derived from a pump (12) and in response to a steering maneuver through a shaft (4) to a servo motor of the gear (1). Downstream of the open center valve (3) is a restrictor (8) through which hydraulic fluid from the valve (3) passes to a reservoir (11). The restriction effected by the restrictor (8) to fluid flow from the valve (3) to the reservoir is variable to provide a throttling action and a back pressure in the line (6) to alleviate noise in the valve (3).

Abstract: A regulator assembly which receives a variable reference signal to control the fluid pressure of a supply fluid supplied to a motor. The variable reference signal which represents the work performed by the motor also passes through a relief valve. When the output torque of the motor reaches a predetermined value, the relief valve opens and a portion of the fluid supplied to the motor is vented to an exhaust conduit to protect any mechanism operated by the motor from receiving excessive torque.

Abstract: A hydraulic control system comprising a hydraulic actuator having opposed openings adapted to alternately function as inlets and outlets for moving the element of the actuator in opposite directions, a pump for supplying fluid to the actuator, pilot operated meter-in valve means to which the fluid from the pump is supplied for controlling the direction of movement of the actuator, meter-out valve means associated with each opening of the actuator for controlling the flow out of said actuator, and a pilot operated check valve operable for controlling flow from the meter-in valve means to one end of the actuator and for preventing flow out the end of said actuator, the pilot operated check valve being operable at a lower pilot pressure than the meter-out valve means and including time delay means such that the valve functions to prevent flow out of the actuator after a predetermined time delay from the time when pilot pressure to said meter-out valve means is interrupted, insuring relief valve protection.

Abstract: A direction flow control valve for control of positive and negative loads equipped with a positive and negative load compensator controlled by a single pilot valve stage responsive to positive and negative load pressure signals.

Abstract: A direction flow control valve for control of positive and negative loads equipped with a positive and negative load compensator controlled by a single pilot valve stage responsive to positive and negative load pressure signals. The positive and negative load compensator is provided with two sets of negative load throttling slots, one set of negative load throttling slots for each actuator port.

Abstract: In a hydraulic apparatus, an operating oil delivered from a fixed delivery hydraulic pump is divided into two parts, one of which is discharged into an oil tank by passing through a serial circuit consisting of a normally open valve and an orifice and the other of which is supplied to a piston-cylinder means by passing through a parallel circuit consisting of a normally closed valve and a check valve. When the normally closed valve is closed and the normally open valve is gradually closed, the piston is raised while gradually increasing in velocity. On the other hand, when the normally open valve is totally opened to stop the piston and the normally closed valve is gradually opened, the piston is lowered while gradually increasing in velocity. When the valves are operated to cause the piston to move vertically, the impact applied thereto at the time when the valve opening is large is largely mitigated by using said orifice.

Abstract: A progressive pneumatic starter device delivers at its outlet an increasing pressure of low flow rate, then a working pressure at a high flow rate. The starter device is provided with a distributor member adapted to connect, in parallel with a calibrated bore, a channel of large section, when a pressure which is greater than a predetermined threshold and which is not derived from the outlet is applied to the distributor member. The starter device is advantageously placed upstream of a pneumatic switch to which it is directly associated for the purpose of shortening its channels for transfer of fluid.

Abstract: A closed center programmed valve system having a load sense fluid source for control of the raising and lowering of load means by a raise and a lower normally closed two stage valve assembly. Each of the second stages of the valve assemblies has a poppet with a parabolic contour which is dimensioned to provide substantially linear flow rate change for minimized shock when the respective valve is actuated to the valve closed state. The load sense for the load means is taken from the outlet of the raise second stage without the requirement of a separate actuated valve or land with a load sense signal being applied to the fluid source during the time the raise valve assembly is actuated to the valve open state.

Abstract: A valve is provided, particularly as a part of a block control device, made up of an elongate housing having a longitudinal bore with spaced work chambers, inlet chambers and exhaust chambers intersecting the bore and an elongate cylindrical spool slidable in said bore, having a second bore in each end of said spool, a brake piston movable in each second bore, a pair of restrictor passage means one in said spool and one in said brake piston connecting the interior of said spool with both ends of each bore in the spool on opposite ends of the piston, a pair of spaced transverse passages at each end of the spool communicating with each bore in the spool and spaced to connect a work chamber and pressure fluid chamber at one end of the spool and a work chamber and exhaust chamber at the other end of the spool in a work position, an annular groove in the brake piston capable of connecting said spaced passages within the bore in the spool whereby in said work position pressure fluid flows from a pressure fluid cham

Abstract: A direction flow control valve for control of positive and negative loads equipped with a positive and negative load compensator controlled by a single pilot valve stage responsive to positive and negative load pressure signals.

Abstract: A direction flow control valve for control of positive loads equipped with a load responsive positive load control, which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between inlet pressure and load pressure and which permits variation in the level of pressure differential in response to an external control signal, while this pressure differential is maintained constant at each controlled level.

Abstract: The telescopically extendable prop (1) has at the periphery of the intermediate prop (3) abutments (30) which cooperate with a valve (15) before the intermediate prop (3) has attained its highest extended position. The valve (15) stops the extending stroke of the intermediate prop (3) and is releasing the beginning of the extending stroke of the top prop (4). As soon as a predetermined pressure is built up in the consolidating conduit (10) of the top prop (4), the valve (27) subjected to this pressure is overacting the valve (15) cooperating with the abutments (30) of the intermediate prop (3), whereupon the consolidating stroke is completed by pressurizing the intermediate prop (3) with pressurizing fluid. (FIG.

Abstract: Fluid control circuits employed on construction vehicles to control the actuation of various work cylinders oftentimes include a system for sensing the fluid pressure in the cylinder and communicating such fluid pressure to a control device in signal form to closely control the displacement of a pump, the flow capacity of a pressure compensated flow control valve, or the like. The sensing system is normally associated with the spool of a directional control valve which must travel a substantial distance to effect extension or retraction of the cylinder and normally requires an "anti-rotation" device to insure proper alignment of the various ports and passages. Conventional high pressure systems of this type also pose potential leakage problems.

Abstract: A direction flow control valve for control of negative load equipped with a pilot operated load responsive negative load control, which automatically regulates valve outlet pressure to maintain a relatively constant pressure differential between negative load pressure and valve outlet pressure and which permits variation in the level of pressure differential in response to an external control signal, while this pressure differential is maintained constant at each controlled level.

Abstract: A pressure reducing valve between a high pressure source and a steering control valve lowers the operating pressure of fluid conducted to a piston servomotor from the source by the steering control valve. A constant pressure differential across the steering control valve is maintained by the pressure reducing valve through a feedback pressure balancing arrangement to appropriately vary regulation of the feed pressure to the steering control valve.

Abstract: A direction flow control valve for control of positive loads equipped with a pilot operated load responsive positive load control, which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between inlet pressure and load pressure and which permits variation in the level of pressure differential in response to an external control signal while this pressure differential is maintained constant at each controlled level.

Abstract: In a load responsive fluid power and control system employing plurality of control valves with positive and negative load compensation, a pressurized exhaust system supplied with make-up fluid from pump discharge circuit by a pressure reducing valve and deactivating valve of the pressure reducing valve operable when the pessurized exhaust system is completely unloaded during control of positive load.

Abstract: A direction flow control valve for control of negative load equipped with a load responsive negative load control, which automatically regulates valve outlet pressure to maintain a relatively constant pressure differential between negative load pressure and valve outlet pressure and which permits variation in the level of pressure differential in response to an external control signal, while this pressure differential is maintained constant at each controlled level.

Abstract: In a hydraulic apparatus, operating oil delivered from a fixed delivery hydraulic pump is divided into two parts, one end of which is discharged into an oil tank by passing through a serial circuit of a normally open valve and an orifice and the other end of which is supplied to a piston-cylinder mechanism by passing through a parallel circuit of a normally closed valve and a check valve. When the normally closed valve is closed and the normally open valve is gradually closed, the piston is raised while gradually increasing in velocity. On the other hand, when the normally open valve is totally opened to stop the piston and the normally closed valve is gradually opened, the piston is lowered while gradually increasing in velocity. When the valves are operated to cause the piston to move vertically, the impact applied thereto at the time when the valve opening is large is largely mitigated by using the orifice.

Abstract: A direction flow control valve for control of positive and negative loads equipped with a load responsive positive load control which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between inlet pressure and load pressure. The load responsive control of direction flow control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A control arrangement for a hydraulically operated load lifting and lowering device includes precontrolled first valve means controlling flow of fluid from a source under pressure to a return conduit leading to a tank or to a working conduit leading to the device and a closer block in the working conduit, including a piston controlling flow of pressure fluid from the working conduit into the device, respectively flow of pressure fluid out of the device into the return conduit downstream of the piston. A throttle is arranged in the return conduit to produce upstream of the throttle a pressure acting on the piston but not on the slide of the first valve means, whereby without increasing the neutral fluid circulation pressure a uniform lowering of the load independent of the magnitude thereof may be obtained.

Abstract: A direction flow control valve for control of positive and negative loads equipped with a load responsive positive load control which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between inlet pressure and load pressure. The load responsive control of direction flow control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A load responsive fluid control system in which system pump controls permit variation in the level of pressure differential in response to an external control signal and which uses direction control valves equipped with load responsive variable pressure differential positive load controls.

Abstract: A pressure operated valve restricts outflow of fluid from a servomotor to which inflow of fluid is controlled by valve elements torsionally interconnected by a torsion bar for limited relative rotation. The pressure operated valve, mounted within one of the valve elements, is displaced by operating pressure of the inflowing fluid in the direction of the outflowing fluid to partially close a return flow valve passage and is under the bias of a spring urging the valve to a position permitting unrestricted outflow through said return flow valve passage.

Abstract: PCT No. PCT/US79/01033 Sec. 371 Date Nov. 29, 1979 Sec. 102(e) Date Nov. 29, 1979 PCT Filed Nov. 29, 1979Heretofore the capability of operating a system (10), which supplies fluid to a hydraulic circuit (12), selectively at either a high or a low flow rate with only a single pressurized fluid source (14) has not existed. Such a system (10) includes a control valve structure (16) for controlling delivery of fluid from the source (14) to drive the circuit (12) and a flow control (22) for metering a portion of the fluid to the circuit (12). The capability of operating such a system (10) selectively at either a high or a low flow rate is advantageous in some modes of operation of the circuit (12). Herein, hydraulic circuitry (86) serves for controlling the magnitude of the portion in response to application of a signal thereto and a device (78) is provided for selectively applying the signal to the circuitry (86) for selectively directly controlling the magnitude of the portion.

Abstract: A control system for operating a double-acting hydraulic ram or motor, including a proportional meter-out type directional-control valve which meters the flow of fluid out of the load and, in association therewith, a combined flow and pressure-control valve in the return line from the load. The flow and pressure-control valve is responsive to the pressure drop across the meter-out orifice of the directional-control valve such that return-line flow is restricted at high pressure drops and the supply pressure to the load is increased at low pressure drops, whereby a substantially constant pressure drop across the meter-out orifice is maintained irrespective of the size or direction of the load.

Abstract: A hydraulic power brake system in which a hydraulic power brake booster has one or more back pressure control valves to produce a restriction downstream of the booster control valve after the booster has been actuated to build up some booster power pressure. This back pressure on the booster control valve is effective to control hydraulic valve noise during booster operation. There is substantially no fluid restriction in the booster when the booster is not actuated. Three back pressure control valve arrangements are disclosed.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump control responding to highest system load. Each direction flow control valve is equipped with a load responsive pressure control which automatically regulates valve inlet pressure to maintain a constant low pressure level at the motor exhaust and a load responsive negative load control to control a constant pressure differential at the motor exhaust. The load responsive control of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A control valve for actuating a double acting hydraulic jack or lift cylinder features a pressure compensator assembly for limiting the rate of retraction of the cylinder and piston relative to each other under heavy loading conditions to prevent dropping a load or letting the load get out of control. Pressure compensation is provided by a floating piston which is movably coupled in releasable engagement with a spool, wherein engagement of the piston with the spool defines a restricted flow path for limiting hydraulic flow out of the blind end of the cylinder to tank during retraction. According to a preferred embodiment, the spool is provided with a plurality of notches defining restricted flow passages which are covered and uncovered by the piston as it moves into and out of engagement with the spool. A compression spring is coupled between the piston and the spool for biasing the piston for movement away from the spool.

Abstract: A hydraulic valve of the type having a plurality of flow directing spools and valve bodies, normally disposed in a stack, or sectional control valve assembly, with registering like passageways on adjacent valve bodies in fluid communication. An open center pilot arrangement is provided to initially control the pressure of fluid supplied to an output passageway of an individual valve when its spool is moved to a position to supply fluid to a load connected thereto. A balanced flow control is disposed in each valve body between an inlet passageway and an outlet passageway and to a loop and an output passageway. The flow control is operative in response to the pressure in one of the output passageways of the valve body to control the proportionate flow of the fluid to the output passageway and the outlet passageway of the valve body. A number of individual valves may be operated in a stack in such a manner that an "upstream" valve will have "priority".

Abstract: This invention relates to a pneumatic cylinder and valve control system in which a block and two plates bolted to the block form one end of the cylinder. This block and plate combination, moreover, provides the housing for the valves and conduits that comprise the pneumatic control system for the operation of the cylinder. To produce greater force, moreover, two pistons mounted within the cylinder on the same line of action both are in fluid communication with the pneumatic control system.

Abstract: A high pressure hydraulic system, including a bidirectional fluid motor having two ports, a pair of normally closed, pilot operated poppet valves, each connected to an associated port, a fluid reservoir, a flow sensor having a flow path interconnecting each of the poppet valves and the reservoir and having an output for providing a signal representing the flow rate, along the flow path, a pair of metering valves each connected to the pilot of an associated poppet valve for controlling the flow of fluid through the associated poppet valve, control signal inputs for each of the metering valves, and flow rate signal inputs connected to the output of the flow sensor for each of the metering valves so that each poppet valve is ultimately controlled by both control signals and the flow rate through the flow sensor.

Abstract: A direction flow control valve in a load responsive system equipped with a positive load compensator, which in the presence of negative load either blocks the pump flow to the motor above a certain predetermined level of the exhaust manifold pressure, or below that predetermined pressure level acts as a pressure reducing valve throttling sufficient fluid flow from the pump circuit to pressurize the exhaust manifold.

Abstract: A control circuit comprises pressurized fluid source (11), a two-position directional control valve (14) and an actuator (13), such as the pump of a hydrostatic transmission, connected to the fluid source and the control valve to be selectively actuated thereby.

Abstract: In a fluid throttling pressure compensated valve remote control of position of valve spool in which the total force acting on the spool is directly proportional to displacement of the spool from its neutral position, irrespective of the pressure differential between the pump pressure and the load pressure or the pressure differential between the load pressure and the reservoir pressure.

Abstract: A power steering device includes a housing which journals coaxial input and output shafts. Drivingly connected to the input shaft is an eccentric which rotatably carries a gear wheel. The gear wheel is prevented from rotating in the housing so that it gyrates when the input shaft rotates. An internally toothed ring meshes with the gear wheel and is drivingly connected to the output shaft. The internally toothed ring defines a greater number of gear teeth than does the gear wheel so that gyration of the gear wheel incident to the rotation of the input shaft drives the output shaft via the internally toothed ring. A valve device is responsive to rotation of the input shaft relative to the output shaft to control fluid flow to and from a fluid motor. The fluid motor is coaxial with and drivingly connected to the output shaft so as to increase the torque derivable from the output shaft incident to rotation of the input shaft.

Abstract: A power steering gear having a piston nut fed with pressure fluid from a source through a rotary valve. The construction includes a special one-way valve assembly in the high pressure port which is formed by a plunger which seats into the end of the steel tube of the power steering hose. The plunger tube and external O-ring provides for improved sealing of the power steering gear to prevent external leaks and to provide for improved control of flow into the housing from the source and to block flow from the housing into the high pressure port so that road excited vibrations are not fed back to the vehicle handwheel.

Abstract: A load responsive direction and flow control valve for use in fluid power load responsive system. The system is powered by a single fixed or variable displacement pump. The valve maintains a selected constant flow level during control of positive loads and automatically blocks pump flow to the actuator in presence of a negative load, providing the actuator inlet flow requirement from the valve exhaust manifold. The direction and flow control valve is equipped with a load responsive control which during control of positive load maintains a constant low pressure level at the actuator outlet and retains its control characteristics in a system in which multiple positive loads are simultaneously controlled.

Abstract: A direction flow control valve for control of positive and negative loads equipped with a load responsive positive load control which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between inlet pressure and load pressure. The load responsive control of direction flow control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A flow control valve in fluid communication with a variable orifice which is utilized to control speed of a fluid motor, the valve providing a constant pressure drop across the variable orifice whereby consistent control of speed of the motor may be maintained.

Abstract: A controller for fluid pressure operated devices such as vehicle power steering systems. The controller is of the type having a primary, rotatable valve member and a follow-up valve member and including a fluid meter having a metering member coupled to the follow-up valve member. The valving defines a central reference plane perpendicular to the axis of rotation of the valving and the various ports and passages defined by the primary and follow-up valve members are generally oppositely and equally disposed about the central reference plane. This valving symmetry reduces internal leakage and steering wheel precession. The controller includes a load signal circuit, including a pair of load sensing grooves oppositely and equally disposed about the central plane.

Abstract: A fluid flow control valve assembly provides metering of the hydraulic fluid from a cylinder port at a constant desired rate for lowering a load at a corresponding constant rate which has been raised by the cylinder. The valve assembly comprises a normally closed valve having an input orifice communicating with the cylinder port and an output orifice and is selectively actuable for permitting the flow of fluid from the cylinder. A normally closed pressure compensating valve has an input orifice communicating with the normally closed valve output orifice, an output orifice, and a control input adapted for direct communication with the cylinder port for continuously sensing the fluid pressure within the cylinder. The pressure compensating valve maintains a constant fluid flow pressure differential and a constant fluid flow rate from the cylinder.

Abstract: A pressurized fluid supply for an auxiliary power steering system includes a regulator valve assembly controlling the output pressure of a fluid supply pump under the opposing influences of the pump discharge pressure and a signal feedback pressure from a fluid operated servomotor. An adjustable bias applied to the regulator valve assembly establishes a low idling discharge pressure for the pump while no steering action is being performed by the servomotor to which the pump is connected by a control valve biased to a flow blocking position.

Abstract: A device for cushioning hydraulic actuators at the end of travel including a unique valve responsive to hydraulic pressure which, one when under system return pressure ports fluid to a chamber of less volume than the actuator cylinder and then through a line restriction for reduced fluid flow and the consequential slowing of the actuator and two when system pressure is off, drains the chamber for use during the next cycle.

Abstract: A compensated work port fluid valve is provided wherein a directional control valve having an inlet chamber, an outlet chamber and a work chamber is provided with a compensator valve connected to the work chamber and having a pressure sensing compensator valve controlling the flow of fluid from the work chamber to a work port to maintain constant pressure at the work port.

Abstract: A hydraulic system including a bidirectional hydraulic motor having first and second fluid ports, a pump, a control valve for selectively connecting the pump to (a) the first port and venting the second port and (b) the second port and venting the first port, a modulating valve interposed between the pump and the control valve for varying flow from the pump to the control valve, a pilot for the modulating valve, and a resolver for selecting the lowest pressure at the motor ports and for directing a fluid signal proportional thereto to the pilot to control the modulating valve.

Abstract: A direction flow control valve for control of positive and negative loads equipped with a load responsive positive and negative load control which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between inlet pressure and load pressure and throttles load pressure to maintain a constant pressure differential between the load pressure and outlet pressure. The load responsive control of direction flow control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: An open center type control valve for a hydraulic motor, wherein pressure fluid from a source is caused to flow from the valve inlet to a motor port at a substantially uniformly metered rate despite fluctuations in the load on the governed fluid motor, due to the operation of a flow control mechanism which regulates bypass of excess fluid through the open center passage to the valve outlet in accordance with variations in the pressure differential between the inlet and outlet end portions of the open center passage.