Abstract: A main flow path that introduces high-pressure air to an air cylinder, or discharges exhaust air therefrom, includes a sub flow path provided alongside the main flow path; an exhaust flow rate adjustment unit that suppresses the operation speed of the air cylinder by adjusting the flow rate of the exhaust air flowing through the sub flow path; and a switching valve that is connected between the air cylinder, the main flow path and the sub flow path, and that connects the main flow path and the sub flow path to the air cylinder in a switching manner. The switching valve is constituted by a spool valve.

Abstract: The invention relates to a hydraulic cylinder, for example for use in a hydraulic tool, comprising at least one piston/cylinder combination composed of a cylinder body and a piston accommodated in said cylinder body and provided with a piston rod that projects from said cylinder body, wherein the cylinder body and the piston body define a first cylinder chamber while the cylinder body, the piston body and the piston rod define a second cylinder chamber, and wherein during operation the piston performs alternating forward and return operational cycles under the influence of a fluidum under pressure that is conducted to the first and the second cylinder chamber through a first and a second line, respectively, and a control valve which regulates the supply of a fluid under pressure through the first or the second line to the piston/cylinder combination.

Abstract: A valve apparatus for setting and monitoring the clamping pressure of a clamping device (9) for workpieces to be clamped, in particular in lathes, has at least one pressure control valve (1A, 1B) for setting the clamping pressure, and has at least one pressure sensor (6A, 6B) detecting the clamping pressure. The clamping pressure is adjusted in relation to a predefinable setpoint clamping pressure. The valve apparatus can set the clamping pressure for safety and monitor it to maintain or reduce it during the machining.

Abstract: A method is provided for, when necessary, automatically limiting a pressure in a hydraulic system during operation. A system is arranged to deliver pressurized hydraulic fluid to at least one fluid actuated device arranged to perform a work function, where the procedure includes sensing a pressure in at least one position of the system, comparing the detected pressure value, or an associated value, with a first predefined pressure limit, and opening a communication of fluid between the fluid actuated device and a reservoir through a first conduit if the sensed pressure value, or an associated value, exceeds the predefined limit.

Abstract: An apparatus comprising: a series of units, each being capable of producing a volume flow; a first channel for supplying hydraulic fluid into the apparatus; a second channel for supplying hydraulic fluid from the apparatus; a first series of valves comprising at least one controlled valve for each unit; a third channel for supplying hydraulic fluid from the apparatus; and several controlled auxiliary valves, each being provided for one unit. The control circuit also comprises: at least one actuator for converting hydraulic energy to mechanical energy, wherein said actuator is at least connected to either the second channel or the third channel; and a control device configured to synchronize the operation of the valves of the first series of valves and said auxiliary valves with the operation of said units, and to control the actuator by means of pressure and volume flow.

Abstract: A method of driving a hydraulic actuator provided with a pressure-controlled proportioning solenoid valve; the method includes the steps of: determining a first open-loop contribution according to a pressurized oil flow rate which crosses the proportioning solenoid valve and according to the desired load pressure inside the actuation chamber; determining a second open-loop contribution according to the desired position of the spool of the proportioning solenoid valve; determining a third closed-loop contribution according to the difference between a desired value of the position of the mobile piston and a real value of the position of the mobile piston; and calculating a desired electric driving current value of the proportioning solenoid valve by means of an algebraic sum of the three contributions.

Abstract: A three-way two-position poppet valve (10) comprising a housing (12) with a generally cylindrical valve chamber (14), a first (20) and a second (16) port with coaxial 1 valve seats (26, 28) at the ends of the chamber, and a third lateral working port (18). A poppet body (36) is disposed reciprocably in the valve chamber so that in a first position of the poppet body the first valve seat (26) is sealed and the second port communicates with the working port, and in a second position the second valve seat (28) is sealed and the first port communicates with the working port. The valve is characterized in that the housing has two coaxial cylindrical passages (24, 30) adjacent the respective valve seats, while the poppet body has two coaxial cylinder parts (44, 48) slidingly and sealingly fitting the cylindrical passages, so that the poppet body is always supported in at least one of the cylindrical passages and fluid communication between the first and the second port is always prevented.

Abstract: The invention concerns a hydraulic valve arrangement (1) with a working connection arrangement having a first working connection (A) and a second working connection (B), both working connections (A, B) being connectable with a hydraulic consumer (2), a supply connection arrangement having a pressure connection (P) and a tank connection (T), a first valve arrangement with a first valve (12), closing the pressure connection (P) or connecting it in a controlled manner with the first working connection (A) or the second working connection (B), a second valve arrangement with a second valve (16), closing the tank connection (T) or connecting it in a controlled manner with the first working connection (A) or the second working connection (B), and a control arrangement controlling the first valve arrangement and the second valve arrangement. In such a valve arrangement, it is endeavoured to achieve improved operation behaviour.

Abstract: An adsorbent fractionator directional flow control valve assembly includes two inlet valves, two exhaust valves, and a valve body. The valve assembly controls the directional flow of an influent gas mixture into one of two vertical desiccant tanks of an adsorbent fractionator, or desiccant dryer, and an effluent gas flowing in reverse through the opposite desiccant tank. The valve body is a single unitary piece, which may be a casting, and couples the inlet valves and the exhaust valves, which may be four identical valve subassemblies, providing flow communication between these and an inlet port, two exit ports, and an exhaust port.

Abstract: The invention relates to a hydraulic actuating device for a movable component of a vehicle, in particular a closure element for closing an opening in a vehicle body, such as for example a movable roof, such as a folding roof or a retractable hard top.

Abstract: An actuating valve has two relay valves connected to a compressed air source and a pneumatic cylinder with two pressure chambers. When one relay valve is actuated, one pressure chamber is pressure-loaded and the other is relieved. Two 3/2 port directional control valves are arranged upstream of the pneumatic cylinder. Two check valves are positioned in branch lines connecting the relay valves and the directional control valves. A control line connects the branch line to the other directional control valve, respectively. The directional control valves are moveable between a first position allowing compressed air to pass and a pressure relief position. When the relay valves are inactive, the directional control valves are in the first position and the relay valves are in a venting position for the branch lines. When one relay valve is actuated, it assumes a position allowing passage of air to the branch line connected to it.

Abstract: A position control system is used for controlling a fluid operated cylinder having at least one fluid chamber defined by a piston located within a housing for movement between first and second end limits of travel. The system includes at least two electrically actuated proportional flow control valves connected to each port of the cylinder for selectively and proportionally controlling fluid flow into and out of the at least one chamber. At least one pressure sensor is provided for measuring fluid pressure with respect to each chamber. At least one discreet position sensor is located adjacent a midpoint of the cylinder for sensing a discreet centered position of the piston. A controller includes a program and is operably connected for controlling actuation of the at least two valves in response to pressure measured by the at least one pressure sensor and location measured by the at least one position sensor.

Abstract: A hydraulic actuating device for moving an object, for example for a retractable hard-top of a convertible car.

Abstract: The invention proceeds from a drive device which is used, in particular, for the closing unit, the injection unit or the ejectors of a plastic injection molding machine and which has a drive element movable axially by means of an electric motor and a hydraulic unit movable as a result of the movement of the drive element in the same direction as the latter. In drive devices for the applications mentioned, it is important first to execute a rapid adjusting movement and then to exert high forces. In a known drive device having the features mentioned, the hydraulic unit is a hydraulic cylinder which, during the adjusting movement, is adjusted by the electric motor via a lifting spindle and to which pressure medium is supplied via a valve for the purpose of exerting a high force. In this known drive device, high reaction forces act on the lifting spindle.

Abstract: A position control system is used for controlling a fluid operated cylinder having at least one fluid chamber defined by a piston located within a housing for movement between first and second end limits of travel. The system includes at least two electrically actuated proportional flow control valves connected to each port of the cylinder for selectively and proportionally controlling fluid flow into and out of the at least one chamber. At least one pressure sensor is provided for measuring fluid pressure with respect to each chamber. At least one discreet position sensor is located adjacent a midpoint of the cylinder for sensing a discreet centered position of the piston. A controller includes a program and is operably connected for controlling actuation of the at least two valves in response to pressure measured by the at least one pressure sensor and location measured by the at least one position sensor.

Abstract: A bobbin creel is supported on a holder so as to be pivotable by a four-bar linkage arranged on the machine frame of a textile machine. The holder forms the stationary member of the four-bar linkage. The bobbin creel is pivotable from a lower loading position into an upper operating position by a pneumatic cylinder connected with one end on the holder and with the other end to one of the movable four-bar linkage members. For pivoting the bobbin creel from the upper operating position into the lower loading position, the pneumatic cylinder is a bidirectional pneumatic cylinder loadable at both ends with compressed air and a correlated actuating valve.

Abstract: A multiway valve for controlling a flow of fluid under pressure, includes a valve housing having fluid ports and a plurality of bores in side-by-side parallel disposition substantially at a same level. Each bore is configured for accommodation of a valve spools which are sealed in the bores against the valve housing. The spools have opposite first and second end faces, and include portions of greater diameter and portions of smaller diameter. Acting on the first end face of the spools is an actuation unit for moving the spools in a longitudinal direction to thereby direct a flow of fluid under pressure between the ports, whereas a mechanical coupling mechanism, which is secured to the valve housing, interacts with the second end faces of the spools.

Abstract: The circuit comprises first and second power lines connected to a port of a first actuator chamber and to the port of a second actuator chamber, respectively; a supply line and a discharge line connected to a supply source and to a discharge reservoir; a first sliding member valve capable of connecting the first power line to the supply and discharge lines under the control of pilot pressures transmitted to the first sliding member valve by a first pair of pilot lines; and a second sliding member valve capable of connecting the second power line with the supply and discharge lines under the control of pilot pressures transmitted to the second sliding member valve by a second pair of pilot lines.

Abstract: In a machine tool by pulse drive of a hydraulic system, a piston of a hydraulic cylinder is connected with a table, and an outflow valve and an inflow valve, which form a pair, are respectively connected with a right and a left hydraulic chamber. When the feed table is moved to the right, for example, control is conducted so that the valve-opening period of one valve can be a portion in the middle of the valve-opening period of the other valve. Since a portion of pressure in the hydraulic chamber is canceled, an effective pressure, the pulse width of which is narrow, remains. Accordingly, even in the case where a common inexpensive electromagnetic valve is used, it is possible to accomplish a smooth feed motion.

Abstract: A valve and position control system integrable with a clamp having at least one clamp arm moveable between a clamped position and a released position in response to movement of an actuator between first and second end limits of travel controlled by differential fluid pressure in first and second chambers located on opposite sides of the actuator. The system allows selective setting of at least one of the clamped position and the released position at an actuator position between the first and second end limits of travel of the actuator. The system selectively controls the speed of actuator movement as the actuator moves between the first and second end limits of travel. Preferably, the system also selectively controls the speed of actuator movement as the actuator approaches at least one of the first and second end limits of travel to provide a soft touch clamp action. The system selectively adjusts pressurized fluid within the first and second chambers independent of one another.

Abstract: Main piston servo-actuation system, with hydromechanic self-contained failure detection device, working with hydraulic fluid supplied by a pump, including two servovalves (1 and 2) which are identical in design, controlling a piston (3) mechanically linked to a position transducer (4) according to the electrical demand (6, 7) supplied by the feedback position control loops (8 and 9) for the servovalves (1 and 2) to the torque motors (12 and 13) of the servovalves. These loops (8 and 9) receive the same piston position request, and they are given feedback at the same time with the same position signal fed by the position transducer (4). The system is furthermore compensated by two pressure selection valves (14 and 15) and by its own interconnection servo lines.

Abstract: In a machine tool by pulse drive of a hydraulic system, a piston of a hydraulic cylinder is connected with a table, and an outflow valve and an inflow valve, which form a pair, are respectively connected with a right and a left hydraulic chamber. When the feed table is moved to the right, for example, control is conducted so that the valve-opening period of one valve can be a portion in the middle of the valve-opening period of the other valve. Since a portion of pressure in the hydraulic chamber is canceled, an effective pressure, the pulse width of which is narrow, remains. Accordingly, even in the case where a common inexpensive electromagnetic valve is used, it is possible to accomplish a smooth feed motion.

Abstract: A weld gun cylinder and piston assembly includes a common center end wall interposed between two cylinders. The common center end wall functions as a manifold with bores extending therethrough. The manifold houses two spool valves. The spool valves control the passage of pneumatic pressure through passages of the manifold to and from the cylinders to extend and retract two piston rods for controlling jaws and a weld tip on a robotic arm.

Abstract: A riding lawn mower is provided that has an engine, a device that requires control and a vacuum actuated control mechanism for controlling the device. The vacuum actuated control mechanism includes a vacuum actuator having first and second chambers separated by a movable membrane, first connecting means for operatively connecting the vacuum actuator to the device, vacuum means for providing a vacuum to the vacuum actuator, activating means for selectively activating the vacuum actuator and securing means for securing the vacuum actuator in place. The securing means also secures the device in place.

Abstract: An electro-hydraulic control device (10, 60) for a hydraulic servo motor for controlling a volume flow is proposed, which is embodied as a 4/2 valve module. A blocking valve in accordance with seat valve technology between a motor connection (B) and a return flow (R) form a lowering element (11), while the associated unblocking member (44) is designed as a longitudinal slide (45), which controls the connection between an inflow connection (P) and a motor connection (A) and is actuated by a proportional magnet (16). After unblocking the blocking valve, its seat valve body (23) is mechanically taken along by the longitudinal slide (45), and the two volume flows are proportionally controlled via the lowering element (11) and the lifting element (12), so that a large switching capacity is achieved along with a construction with few leaks.

Abstract: A fluid controlled switching unit includes a valve block; a guide bore provided in the valve block; first and second work chambers provided in the valve block and spaced from one another; first and second cylinder bores provided in the valve body; and a plunger rod guided in the guide bore for reciprocating motion therein along a displacement path. The plunger rod has first and second piston faces situated in the first and second work chambers, respectively, and exposed to fluid pressure prevailing therein. The first and second piston faces move in the first and second cylinder bores, respectively. A valve body is attached to the plunger rod for forming a unitary structure therewith. The valve body has opposite pressure faces as well as first and second opposite end positions determining opposite ends of the displacement path. The valve body, when situated in one of the end positions, is exposed solely unilaterally to fluid pressure at one of the pressure faces thereof.

Abstract: A dual piston pilot valve includes a housing forming first and second cylinders. A first spool is moveable in the first cylinder for engaging the a piston to effect movement of the first piston and a second spool is moveable in the second cylinder for engaging a second piston to effect movement of the second piston. The valve further includes a single pressurized fluid supply port communicating with both the first and second cylinders, a first output port communicating with the first cylinder, a second output port communicating with the second cylinder, a single exhaust port communicating with both the first and second cylinders, and a diaphragm engaging the housing and both the first and second pistons. The diaphragm is positioned between both the first and second spools and both the first and second seal regions of the first and second pistons to effect a seal between the single exhaust port and the first and second spools.

Abstract: The present invention relates generally to agricultural machinery and, more particularly, to a device for controlling a double-acting steering cylinder of a steering system, having two working connections of the steering cylinder, wherein the working connections are each connected by means of an input pipe or an output pipe to a valve unit, which comprises two switching valves that can be moved alternately into a first switching position and into a second switching position and the steering cylinder in the first switching position of the first switching valve admits a fluid at the first working connection and the steering cylinder in the second switching position of the second switching valve admits the fluid at the second working connection.

Abstract: An electro-pneumatic control system pneumatically connected to a pressure source and electrically connected to an electrical signal source includes a selector switch having an electrical input connected to the electrical signal source, and having a first electrical output and a second electrical output. The system further includes a body having a movable member positioned therein, wherein the body has a first port and a second port; a first regulator valve having a bidirectional port connected to the first port of the body, having an input port connected to the pressure source, having an exhaust port, and having an electrical actuator connected to the first electrical output of the selector switch; and a second regulator valve having a bidirectional port connected to the second port of the body, having an input port connected to the pressure source, having an exhaust port, and having an electrical actuator connected to the second electrical output of the selector switch.

Abstract: In a hydraulic control system including a valve device B for controlling a hydraulic fluid supplied from a hydraulic pump A to a hydraulic cylinder C, the valve device comprises a spool 16 slidably fitted into a valve body 1, and a non-leak valve 27 for controlling communication of an actuator passage 19. The non-leak valve comprises a main valve section 40 including a seat valve 41 provided in the valve body, and a pilot control section 60 including a pilot poppet valve 61 provided in an end cover 31. The seat valve is controlled in proportion to an opening of the pilot poppet valve, and a relief valve 55 for preventing the hydraulic cylinder from being subject to an overload is built in the seat valve. The non-leak valve thus fulfills a load holding function and an overload relief function. By arranging the non-leak valve and the spool in two lines, the valve device can be made more compact.

Abstract: A valve device (1) for fluid flow control includes two independent valves comprising two movable valve bodies (4, 5) within two valve spaces (V1, V2), wherein each valve body is controllable against the force of a return spring (7, 8) acting thereon. The invention is distinguished inthat the valve spaces (V1, V2) are located axially with respect to each other in one common housing (2, 3),that the housing between the two valve spaces is provided with an essentially fixed separating means (6) against which the two return springs are resting,that the housing comprises a common discharge channel (11) which communicates with the two valve spaces, andthat the device comprises a double one-way valve function (9, 10) in the area of the discharge channel in order to prevent unintentional flow actuation resulting from overflow between the valve spaces.

Abstract: A fluid-controlled actuator assembly for a gearbox of a vehicle. The actuator is provided with a four-position mobile element, with a first and a second chamber separated in a sealed manner from the mobile element, and with auxiliary positioning elements suitable for determining a stop position of the mobile element. Also included are first and second solenoid valves suitable for supplying pressurized fluid respectively to the first and to the second chamber and for discharging it from them, such that when the fluid is supplied into both the chambers, the mobile element is maintained by the auxiliary positioning elements in the stop position. When the fluid is supplied into one of the chambers and is discharged from the other, the mobile element adopts one of two lateral positions with respect to the stop position.

Abstract: A hydraulic pilot valve has a joystick which is normally maintained in a neutral position by coil springs acting on plungers which engage corresponding first cam surfaces of a cam fixed to the joystick. The plungers are each connected to respective valve members which are stroked to open the pilot valve when the plungers are depressed. When the joystick is pivoted to depress one of the plungers by engaging the head of the plunger so as to stroke one of the valve members, that valve member is held stroked by an magnetic detent. The joystick may then be released and the valve member will remain in its stroked position. When the joystick is moved back towards a neutral position, a second cam surface on the joystick engages an outer end portion of the depressed plunger and applies an axial force to the plunger. This disengages an armature component of the magnetic detent from an electromagnetic component.

Abstract: Method for controlling a pressurized fluid-actuated double acting cylinder in an assembly such as a hydraulic tightening spanner (1) with a control unit therefor, wherein a piston (5) may be reciprocated repeatedly, firstly with an active stroke providing a desired maximum force, and then with an opposed passive stroke returning the piston (5) to its starting point to enable repetition, and wherein said method comprises selecting a set fluid pressure corresponding to the desired maximum force (Fr) and measuring the time elapsed (Te) between the beginning and the end of the passive return stroke to determine that the force has been achieved. A device for implementing the force is also disclosed.

Abstract: A control system is provided for use in a hydraulic system to provide a simple arrangement with a limited number of elements that bypasses the system flow in the event of an electrical malfunction in the system and further allows other hydraulic circuits to operate even if one or more of the hydraulic circuits have experienced an electrical malfunction. The subject arrangement uses an electro-hydraulic fluid flow control valve mechanism in conjunction with directional valve mechanisms that have at least three functional positions and are controlled by associated electrically controlled displacement control mechanisms in response to receipt of electrical signals from an electrical controller.

Abstract: A servo valve arrangement with a high-pressure, low-pressure and motor connection and with a pressure control valve arranged between the high-pressure connection and motor connection and a return control valve arranged between the motor connection and low-pressure connection is provided. The pressure control valve normally is closed and the return control valve normally is open. The pressure control valve can be opened by a common actuating member whilst closing the return control valve. The valve arrangement is suitable, in particular, for hydraulic power steering systems of motor vehicles with a so-called closed center.

Abstract: A hydraulic pilot valve has a joystick which is normally maintained in a neutral position by coil springs acting on plungers which engage corresponding first cam surfaces of a cam fixed to the joystick. The plungers are each connected to respective valve members which are stroked to open the pilot valve when the plungers are depressed. When the joystick is pivoted to depress one of the plungers so as to stroke one of the valve members, that valve member is held stroked by an magnetic detent. The joystick may then be released and the valve member will remain in its stroked position. When the joystick is moved back towards a neutral position, a second cam surface on the joystick engages an outer end portion of the depressed plunger and applies an axial force to the plunger. This disengages an armature component of the magnetic detent from an electromagnetic component. A spring then pushes the plunger to its neutral position where the plunger holds the valve member operated thereby closed.

Abstract: Disclosed is a stiffness enhanced electrohydrostatic actuator for aircraft flight controls which eliminates the requirement for a central hydraulic system. The actuator replicates the blocked port condition of the central hydraulic system to provide static and dynamic stiffness by the use of valves having a first sleeve and spool and a second sleeve and spool disposed on either side of a valve seat with the first spool biased towards the valve seat.

Abstract: A control arrangement for at least one hydraulic consumer in which the consumer can be controlled with respect to direction and speed via a directional control valve device, in which two consumer lines lead from the directional control valve device to the consumer, each of which consumer lines can be connected to a pump and a tank respectively via a directional control valve piston and a metering restrictor and in which a throttle valve having a servo-piston is associated with each consumer line. The consumer is to be held free of leakage oil in a given position.

Abstract: A two stage valve assembly responsive to signals from a control system for supplying pressurized fluid to two load lines. The first stage includes a motor that directs pressurized fluid from a jet pipe toward a receiver assembly having two receiver ports and a bleedoff area disposed between and separating the receiver ports. The second stage assembly includes two spool/sleeve assemblies that control the flow of pressurized fluid to and from the two load lines. A drain line from the receiver assembly includes a pressure relief valve, which insures that both spool/sleeve assemblies will be servo-controlled at all times. Cartridges may be inserted in the spool/sleeve assemblies to linearize the relationship between input current from the control system and the output force of an unequal area actuator connected to the load lines.

Abstract: A reciprocating piston fluid powered motor which has a fluid inlet and a fluid outlet. Reciprocation of the piston is controlled by a reciprocable valve spool which communicates with the fluid inlet and fluid outlet. The valve spool cooperates with a valve slide which is shiftable on said valve spool to control spool reciprocation. Fluid flow through the fluid inlet and outlet is controlled by electrically actuated solenoid valves connected in flow communication to the fluid inlet and a park port. An electric pulse width modulating switch is connected to each solenoid valve and has a plurality of positions to enable the piston to reciprocate at continuous low and high speed as well as in an intermittent mode. The switch may also be connected to an air powered washer fluid pump to deliver cleaning fluid on command.

Abstract: An external air valve for a reciprocating air motor is provided with a the ability to transfer heat from incoming compressed air into the valve cups to prevent icing and a low friction mechanism for the valve slide to enhance reliability. The design has a housing which forms an air chamber, and located in the air chamber is a slide member containing two cups which alternately cover ports leading to the upper and lower chambers of the air motor piston. The slide has slotted rollers to reduce pneumatic loading and decrease friction during sliding. The shift rod is provided with a central valve spring located in an aperture in the slide, along with spring retaining plates to provide and assist in shifting the valve in conjunction with a detent to assure that the valve is positioned in one of two operating positions. The pressurized chamber, in conjunction with fins, apertures and other heat transfer apparatus in the slide assures that heat is applied to the cups of the slide in order to prevent icing.

Abstract: A valve control system for controlling the operation of a pressure fluid-activated device such as a hydraulic cylinder includes a valve housing having an internal, sealed valve chamber therein. A valve spool is slidably disposed for lengthwise movement within the valve chamber, the valve spool having a valve member for selectively admitting a pressure fluid through passages in the vale housing. A movable handle for manual operation of the valve is connected to the valve spool by a connecting mechanism, whereby movement of the handle causes lengthwise movement of the valve spool relative to the valve housing. A neutral-centering tactile feedback mechanism applies a return force to the handle when the handle is in an operative position. The return force varies in proportion to the pressure of the pressure fluid within the valve, which pressure actuates the device. The feedback mechanism ceases to apply the return force when the handle returns to a neutral position.

Abstract: An external air valve for a reciprocating air motor is provided with a the ability to transfer heat from incoming compressed air into the valve cups to prevent icing and a low friction mechanism for the valve slide to enhance reliability. The design has a housing which forms an air chamber, and located in the air chamber is a slide member containing two cups which alternately cover ports leading to the upper and lower chambers of the air motor piston. The slide has slotted rollers to reduce pneumatic loading and decrease friction during sliding. The shift rod is provided with a central valve spring located in an aperture in the slide, along with spring retaining plates to provide and assist in shifting the valve in conjuction with a detent to assure that the valve is positioned in one of two operating positions. The pressurized chamber, in conjunction with fins, apertures and other heat transfer apparatus in the slide assures that heat is applied to the cups of the slide in order to prevent icing.

Abstract: An axial piston-type servomotor uses control connections on the working cylinder and corresponding control edges on the working piston, together with selector valve apparatus for controlling the working piston into a central stroke position.

Abstract: A control force input system for a balance beam pneumatic valve positioner which does not allow the controlled apparatus to make a full travel motion when the overall control signal is removed. The control force is transmitted to the balance beam or other force summing bar using a linear solenoid coupled to a control spring coupled to the balance beam. When the motive power control signal is removed from the linear solenoid, the balance beam establishes an equilibrium position based on the existing position of the linear solenoid. The solenoid shaft extends into a captive cylinder. A piston connected to the solenoid shaft is located in the captive cylinder and forms two chambers in the cylinder. A solenoid valve connects a port in each chamber. When the solenoid valve is activated, the piston is free to travel. When the solenoid valve is deactivated, as when the control signal is removed, the piston is held in position, locking the solenoid shaft in position.

Abstract: A control force input system for a balance beam pneumatic valve positioner which does not allow the controlled apparatus to make a full travel motion when the overall control signal is removed. The control force is transmitted to the balance beam or other force summing bar using a linear solenoid coupled to a control spring coupled to the balance beam. When the motive power control signal is removed from the linear solenoid, the balance beam establishes an equilibrium position based on the existing position of the linear solenoid. Split wedges are repelled from the linear solenoid when a control signal is applied, releasing the solenoid shaft for movement. Alternatively, split slides are repelled from each other when a control signal is applied, releasing the solenoid shaft bias spring. When the control signal is removed, the split wedges or split slides are biased and attracted to the solenoid, locking the solenoid shaft in position. A variation for use with a current to pressure transducer is detailed.

Abstract: Hydraulic control of reversible hydraulic motors typically requires several different valves to provide for the various operating parameters. The subject hydraulic control circuit has only a pair of electrohydraulic control valves to provide all the typical operating parameters. Operation of the control valves is controlled by a microprocessor in response to receiving command signals from a manually controlled command signal outputting device which establishes a desired fluid flow rate and direction of flow through the control valves.

Abstract: A directional control valve for a pneumatic cylinder in which a piston of the cylinder can be lowered and elevated in a high speed with a minimum air consumption and the lowering/rising speed of the piston can be controlled before it reaches the upper/lower end portions to prevent bounding of the piston.

Abstract: An industrial truck has a hydraulic fluid supply and at least one double-acting hydraulic cylinder assembly for moving a movable element of the vehicle. The cylinder assembly includes a cylinder having a fluid chamber therein, and a piston movable axially in the cylinder. An actuator rod extends from the piston for connection to the movable element. The piston divides the fluid chamber into a rod end chamber and a piston end chamber each having hydraulic fluid therein. A pair of two-way two-position poppet valves are selectively actuatable between a first joint state in which both of the valves are in a normally closed position in which the piston does not move; a second joint state in which a first one of the valves is closed and a second one of the valves is open to move the piston in a first direction; and a third joint state in which the first one of the valves is open and the second one of the valves is closed to move the piston in a second direction opposite to the first direction.