Abstract: The invention relates to hydraulic control in a hydraulic system for the operation of a machine tool such as a press for processing material of a certain type, especially for the operation of the scrap cutters. Said control allows for impact attenuation and combined rapid motion switching with load compensation and transfer of a hydraulic medium of a hydraulic cylinder for the movement of the other. According to the invention, said control comprises hydraulic media of a hydraulic cylinder for pre-control of a first main valve element (2.4.0), a second main valve element (2.7.0) and a third main valve element (3.7.0) which are functionally combined and a fourth valve (2.5).

Abstract: A hydraulic actuating device for moving a retractable hard-top of a convertible car. The actuating device comprises a double-acting hydraulic actuator, the first connection of the actuator being in communication with an associated throttling assembly which is designed to provide either an optionally controllable throttling or a clear passage opening, which is larger than the throttling opening, as a function of a switching parameter. The throttling assembly has a pressure-detection means for detecting the hydraulic pressure in the second working chamber, which pressure-detection means has associated with it a predetermined switching pressure. The throttling assembly is designed such that—when pressurized hydraulic fluid is supplied to the second working chamber—the clear passage opening is active if the detected pressure in the second working chamber is above the switching pressure and that the throttling is active if the detected second working chamber hydraulic pressure is below the switching pressure.

Abstract: A crowd control mechanism for a power shovel includes an extendible dipper handle having an extended position and a retracted position. A double acting hydraulic cylinder having a an extendible ram has one of the cylinder and the ram fixed to the dipper handle and the other of the cylinder and the ram is stationary relative to the dipper handle. At least one of the cylinder and the ram have at least one of a blind end port and a rod end port, and at least one of the cylinder and the ram have the other of the blind end port and the rod end port, wherein hydraulic fluid flowing into the cylinder through the blind end port urges the ram toward an extended position to extend the dipper handle, and hydraulic fluid flowing into the rod end port urges the ram toward a retracted position to retract the dipper handle. Hydraulic fluid flowing into and out of the cylinder is controlled by one or more pilot operated poppet valves.

Abstract: A fluid powered vehicle seat adjustment system comprising a fluid actuator a source of pressurized hydraulic fluid and a controller. The fluid actuator including first and second inlet/outlet conduits, and the controller selectively controlling and directing pressurized fluid selectively to either the first or second inlet/outlets of the actuator. The actuator further comprising actuator isolation valves associated with each of the first and second inlet/outlets of the actuator. Each actuator isolation valve allowing a flow of fluid from the actuator only when pressurized fluid is supplied to the actuator and other isolation valve in order to prevent movement of the actuator except when pressurized fluid is supplied to the actuator.

Abstract: An attachment control system includes an electrical control system and hydraulic control system. The electrical control system interfaces with the hydraulic control system to ensure that attachment decoupling in response to operator electrical control can occur only when at least two different hydraulic threshold conditions are satisfied. In one example, decoupling is prevented unless the attachment is safely positioned (e.g., full curl) in response to operator manipulation of a joystick or other attachment positioning device. This can be detected, for example, when the hydraulic system has an overall operating pressure at or above a first threshold and a joystick pilot pressure at or above a second threshold.

Abstract: A regeneration manifold for a hydraulic system used with a tool attachment on construction and demolition equipment redirects fluid from a reservoir back to the extension chamber to extend the cylinder at a much higher rate when the tool attachment is under little or no load.

Abstract: A hydraulic valve system (1) has a supply connection arrangement, having a high-pressure connection (P) and a low-pressure connection, with a working connection arrangement, having two working connections (A, B), with a control valve (3), which is arranged between the supply connection arrangement and the working connection arrangement, and with a non-return valve (24, 28) for each working connection (A, B). The valve being arranged between the control valve (3) and the working connection arrangement. A tappet (36) mechanically opening the valve element (25, 29) of said non-return valve.

Abstract: A valve arrangement including a release valve. The valve arrangement controls a cylinder assembly including a first port and a second port, and a cylinder slideably housing a piston for movement between an extended position and a retracted position. The valve arrangement includes a valve assembly in fluid communication with the source of fluid pressure and with the first port and the second port to control fluid flow between the source and the first port and second port, and a release valve fluidly connected to the first port and to the second port, the release valve being operable to control flow of fluid from the first port and from the second port. The release valve is movable between a closed position and an open position. Fluid flows from both the first port and the second port simultaneously when the release valve member is in the open position.

Abstract: A suspension for the boom of a loading vehicle includes a hydraulic cylinder for raising and lowering, or for extending and retracting (in the case of a telescopic cylinder), a boom. A direction control valve is provided for selectively routing hydraulic oil to and from at least a head-end chamber of the cylinder. A position sensor senses the position of the hydraulic piston rod, at the start of operation, and sends a sends a target signal representing this beginning position to a control unit which determines the difference between the target signal and a signal representing a current position of the piston rod. When this difference equals a preset difference threshold, a pressure-limiting unit, in the form of a valve or choke, is activated so as to control fluid flow to and from the head-end chamber so as to return the piston rod to its initial position which generated the target signal.

Abstract: An oil pressure operated pump for marine steering gears includes a multiple piston oil pressure operated pump controlled by a steering wheel, a valve housing mounted under the pump, a bottom cover closing the valve, the valve housing and the cover each including channels, threaded holes for reciprocal fastening thereof, non-threaded bores for oil pressure connections, a valve set lodged in the valve housing for non-return and adjustment of oil flow, the valve set including a generally parallelepiped shaped tubular shell having a generally external square shape, a central tubular through-hole, and lathe-turned ducts, a double acting oil pressure cylinder including a shaft movable in the central tubular through-hole for controlling a direction of an engine or rudder of a boat, and valves for controlling fluid flow and thereby movement of the shaft.

Abstract: An electronic control for damping oscillation of a swinging backhoe assembly includes a crossover valve that connects the hydraulic lines that supply hydraulic fluid to the boom swing cylinders to each other whenever an electronic controller senses incipient oscillation or swinging of the backhoe assembly. The electronic controller senses such parameters as pressure in the conduits and the position of the operator controls or the position of the boom swing control valve that the operator controls to determine incipient oscillation when the backhoe assembly is stopped. The crossover valve may remain open for a predetermined period of time.

Abstract: A first control valve selectively connects a first port of a double acting actuator to either a pump supply line or a tank return line, and a second control valve selectively connects a second port of the actuator to either a pump supply line or a tank return line. A first pilot operated check valve restricts fluid flow to a direction only from the first control valve to the first workport unless a pilot pressure from the second port is sufficient to open the valve for the opposite flow direction. A second pilot operated check valve restricts fluid flow to a direction only from the first control valve to the second workport unless a pilot pressure from the first port is sufficient to open the valve for the opposite flow direction. A load sense circuit is incorporated to produce signal indicating the greater pressure at the actuator ports.

Abstract: A control valve is provided which may be incorporated within a fluid operating system. The valve has an internally-mounted check element which allows the valve to provide a fail-safe mode for a downstream device in fluid communication with the control valve. The invention includes the control valve, the valve in combination with a downstream device, and a method whereby the flow of pressurized fluid is controlled by operation of the control valve.

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 first control valve selectively connects a first port of a double acting actuator to either a pump supply line or a tank return line, and a second control valve selectively connects a second port of the actuator to either a pump supply line or a tank return line. A first pilot operated check valve restricts fluid flow to a direction only from the first control valve to the first workport unless a pilot pressure from the second port is sufficient to open the valve for the opposite flow direction. A second pilot operated check valve restricts fluid flow to a direction only from the first control valve to the second workport unless a pilot pressure from the first port is sufficient to open the valve for the opposite flow direction. A load sense circuit is incorporated to produce signal indicating the greater pressure at the actuator ports.

Abstract: A hydraulic valve system (1) has a supply connection arrangement, having a high-pressure connection (P) and a low-pressure connection (T), a working connection arrangement, having two working connections (A, B), which can be connected with a hydraulic motor (2), and a directional valve (4) between the supply connection arrangement (P, T) and the working connection arrangement (A, B), which is connected with the working connection arrangement (A, B) via working lines (17, 18), in which are arranged check valves (21, 22), which can be opened by means of pressure.

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 sleeve carries a check ball valve assembly to form a valve cartridge. The cartridge is insertable into a manifold to communicate with a control valve to extend or retract a piston cylinder in response to pneumatic or hydraulic pressure. The manifold may be contained within a piston end block. The cartridge is selectively removable from the manifold.

Abstract: A valve unit having an overridable check valve. On a valve housing a first and a second power connection are provided, which are connected by way of a power duct, on which an overridable check valve is placed, which may be overridden by a fluid control signal, such control signal being able to be supplied to a signal input connection on the valve housing. The valve housing is additionally fitted with a signal output connection communicating with the power duct.

Abstract: A fluid operated actuator includes a shaft and a housing. The shaft is at least partially mounted in the housing for relative rotation between the shaft and the housing. The shaft includes a substantially central bore in which a first piston is mounted. The shaft also includes a fluid inlet that is connectable to supply of pressurised fluid and a fluid outlet. A conduit is provided for the flow of fluid between the inlet and the outlet. One end of the housing includes a chamber in which there is mounted a valve assembly comprising a second piston and a valve arranged to selectively open or close an inlet to the chamber. Fluid exiting the outlet opens the valve and exerts a force on the second piston, causing movement thereof in a first direction.

Abstract: At a step of pressurizing a workpiece after reducing a speed of a piston rod at an end of a forward stroke of the piston rod by restrictively allowing compressed air to flow out of an exhaust-side pressure chamber, operation of a rapid exhaust valve is triggered by reduction of internal pressure of the exhaust-side pressure chamber to lower pressure than internal pressure of a pressurizing-side pressure chamber to thereby directly open the exhaust-side pressure chamber into the atmosphere through the rapid exhaust valve and rapidly reduce back pressure of a main piston remaining in the exhaust-side pressure chamber.

Abstract: A control valve is provided which may be incorporated within a fluid operating system. The valve has an internally-mounted check element which allows the valve to provide a fail-safe mode for a downstream device in fluid communication with the control valve. The invention includes the control valve, the valve in combination with a downstream device, and a method whereby the flow of pressurized fluid is controlled by operation of the control valve.

Abstract: A cylinder has a rotating member, a cap, a piston, a collar, two control valves and two check valves. The piston is moveably mounted between the rotating member and the cap. The piston has a flange dividing the inner space between the rotating member and the cap into two chambers. The control valves are attached to the rotating member, respectively communicate with the chambers and respectively communicate with two I/O channels in the collar. The check valves are attached to the rotating member, respectively communicate with the chambers and respectively communicate with the I/O channels in the collar. Accordingly, the thickness of the flange of the piston can be decreased so as to reduce the weight of the cylinder, and the torsion for rotating the cylinder and the load to the axle of the machine are also reduced.

Abstract: A method for retrofitting a swing damping circuit to a work vehicle such as a backhoe includes disconnecting a boom swing valve from a boom swing cylinder, and coupling the swing damping circuit to the boom swing valve. Alternatively, it may include replacing a boom swing valve with a combined boom swing valve and swing damping circuit that form a unitary valve body.

Abstract: An insert or cartridge that fits into a cavity in a valve body provides a check valve function and an anti-cavitation function and a pressure relief function. This insert is substantially circular and has an internal cavity with a valve assembly that has two pairs of valve seats, one pair of valve seats providing the anti-cavitation function and the other pair of valve seats providing the pressure relief function. The outside of the insert itself engages with a sealing surface in the cavity in the valve body to provide the check valve function.

Abstract: A rotary cylinder assembly for a machine tool is provided that includes a lock check system that locks the work piece to the machine tool chuck and prevents extension and retraction of the work piece in the event of loss of hydraulic or pneumatic pressure. The rotary cylinder assembly includes a shaft end cover coupled between a fluid shaft housing and a cylinder body. The shaft end cover houses the lock check system and includes a number of flow paths that provide for extension and retraction of a piston rod connector housed in the cylinder body in response to fluid pressure supplied from the fluid shaft housing. The shaft end cover and lock check system are configured to allow small diameter cylinder bodies to be coupled thereto while providing the safety and functional features associated with the lock check system.

Abstract: A hydraulic boom control system has two valves controlling linear hydraulic actuators, one for pivoting a hoist boom relative to a machine and one for pivoting a stick boom relative to the hoist boom. The bore sides of the actuators are hydraulically connected and the rod side of the hoist actuator is connected to the first port of the first valve and to the second port of the second valve. Operating the first valve moves the boom end generally horizontally and operating the second valve moves it generally vertically.

Abstract: A drive device comprising a closed hydraulic circuit which has a hydraulic drive adapted to be actuated by hydraulic medium and has a hydraulic pump responsible for the supply and removal of the hydraulic medium to and from the hydraulic drive. For the operation of the hydraulic pump an electric motor is provided. The activation of the hydraulic drive is controlled by the operational state of the hydraulic pump.

Abstract: A hydraulic cylinder in which the cylinder head contains the main control valve for the cylinder. In one fluid path from the main control valve to an area located on one side of the cylinder's piston, fluid is directed through a transfer tube that extends through the center of the piston and terminates within a hollow ported section of the piston rod. The cylinder head can additionally include two electrically-actuated pilot valves and two pilot-operated check valves. The pilot-operated check valves are located in different passages that extend to areas located on opposite sides of the piston. The pilot-operated check valves include structure that, in combination with passages in the cylinder head, cause both pilot-operated check valves to open when pressurized fluid is being directed to one of the pilot-operated check valves by the main control valve. In the preferred embodiment, electrical wiring to the cylinder head travels through one of the fluid hoses connected to the cylinder.

Abstract: A control device for a hydraulic control motor includes at least one valve controlled actively by an actuating force and at least one passive valve which is operatively connected to the actively controlled valve and which is co-controlled via a line.

Abstract: A hydraulic valve arrangement includes a control valve (3), which, in a first operating position (5), connects a motor connection (21) with a pump connection, in a second operating position (6), connects a motor connection with a tank connection, and, in a locking position (4), disconnects the motor connection (21) from the pump and tank connection. A locking valve (19) is coupled between the control valve (3) and the motor connection (21), dividing the motor line (22) into a first section (23) allocated to the control valve (3) and a second section (24) allocated to the motor connection (21). For the locking valve (19), a pressure release valve (20) in the shape of a seated valve is provided that is fixed to the housing thereby improving control accuracy.

Abstract: In an hydraulic operating arrangement the working chambers (3, 4) of a double-acting working cylinder (1) are connected respectively by way of one reciprocally unlockable check valve (8, 9) with respectively one side of a reversible pressure medium source (11). The respective working chamber (3, 4) under pressure is connected with a joint, controllable proportional pressure regulating valve (15) for pressure control. On its exit side the proportional pressure regulating valve is connected with the pressure medium lines (6, 7) by way of respectively one check valve (18, 19) that opens in the direction of the pressure medium lines (6, 7), in particular between the corresponding unlockable check valves (8, 9) and the respectively belonging working chamber (3, 4) of the working cylinder (1).

Abstract: A double acting actuator is used for operating a pair of latches, and is controlled through a manifold that will permit a base end of the actuator to remain under pressure, and accommodate valve and piston leakage by connecting the rod end of the actuator to drain through a small orifice. The manifold additionally has relief valves for providing different pressures for the rod and base ends of the actuator, and a flow divider that provides a low flow to the actuator while the main flow from a pump is used for other hydraulic components.

Abstract: A hydraulic cylinder in which the cylinder head contains the main control valve for the cylinder. In one fluid path from the main control valve to an area located on one side of the cylinder's piston, fluid is directed through a transfer tube that extends through the center of the piston and terminates within a hollow ported section of the piston rod. The cylinder head can additionally include two electrically-actuated pilot valves and two pilot-operated check valves. The pilot-operated check valves are located in different passages that extend to areas located on opposite sides of the piston. The pilot-operated check valves include structure that, in combination with passages in the cylinder head, cause both pilot-operated check valves to open when pressurized fluid is being directed to one of the pilot-operated check valves by the main control valve. In the preferred embodiment, electrical wiring to the cylinder head travels through one of the fluid hoses connected to the cylinder.

Abstract: A speed controller has a pilot check valve having a first body which has a first fluid inlet/outlet port defined in an end thereof and a pilot port defined in an opposite end thereof. A flow control valve has a second body integral with the first body. A pipe joint has a third body which has a second fluid inlet/outlet port defined in an end thereof and, the third body being integral with the second body. A flow adjustment screw is disposed in the flow control valve and extends into a fluid passage which interconnects the first fluid inlet/outlet port and the second fluid inlet/outlet port, for adjusting a rate of flow of a fluid under pressure in the fluid passage. A valve body is disposed in the pilot check valve for opening a fluid passage which interconnects the first fluid inlet/outlet port and the second fluid inlet/outlet port in response to a pilot fluid pressure supplied from the pilot port.

Abstract: A speed controller has a pilot check valve having a first body which has a first fluid inlet/outlet port defined in an end thereof and a pilot port defined in an opposite end thereof. A flow control valve has a second body integral with the first body. A pipe joint has a third body which has a second fluid inlet/outlet port defined in an end thereof and, the third body being integral with the second body. A flow adjustment screw is disposed in the flow control valve and extends into a fluid passage which interconnects the first fluid inlet/outlet port and the second fluid inlet/outlet port, for adjusting a rate of flow of a fluid under pressure in the fluid passage. A valve body is disposed in the pilot check valve for opening a fluid passage which interconnects the first fluid inlet/outlet port and the second fluid inlet/outlet port in response to a pilot fluid pressure supplied from the pilot port.

Abstract: A drive device comprising a closed hydraulic circuit which has a hydraulic drive adapted to be actuated by hydraulic medium and has a hydraulic pump responsible for the supply and removal of the hydraulic medium to and from the hydraulic drive. For the operation of the hydraulic pump an electric motor is provided. The activation of the hydraulic drive is controlled by the operational state of the hydraulic pump.

Abstract: A working cylinder (A) having at least one working chamber (6, 7) defined by the cylinder barrel (1), at least one of the end sections (2, 3) and a piston (4), at least one supply port (9a, 9b) and a exhaust port (12a, 12b) for the working medium. The exhaust port (12a, 12b) has a valve (13a, 13b) that may be regulated by the pressure of the working medium, which is applied at the supply port (9a, 9b) in order to obtain a smaller dimension of at least the valve and to better utilize the already existing space, specifically within the cylinder, and to better and more efficiently adjust the output capacity of the individual elements. A valve (V), particularly a switch valve (W) of a rocker valve design has therefore at least one inlet (16) and at least one outlet (17a, 17b) for the working medium, as wells as at least one control port (18).

Abstract: Earthmoving machines are often provided with quick coupling devices that allow them to change work implements in a relatively rapid fashion when compared to changing conventionally mounted implements. A locking system between the machine linkage and the implement is positioned between the components and includes a hydraulic system which continually applies pressurized fluid to the locking system.

Abstract: In a power steering device, a pump supplies a pressure fluid. A power cylinder has left and right chambers and is driven in accordance with a pressure difference between a pressure fluid supplied to the left chamber and that to the right chamber. A flow channel selector valve selectively switches a supply direction of the pressure fluid from the pump to the chambers of the power cylinder in response to steering operation of a steering wheel. Fluid paths connect the flow channel selector valve and the corresponding chambers of the power cylinder to each other. Variable restrictors are disposed in the fluid paths, respectively, to control flow rate of the pressure fluid from the power cylinder to the flow channel selector valve. Check valves are respectively connected to the fluid paths in parallel to the corresponding variable restrictors to prevent a flow of the pressure fluid from the power cylinder to the flow channel selector valve.

Abstract: A control apparatus for an industrial vehicle is disclosed. The vehicle has a rear axle that is swingable during straight travel of the vehicle and can be fixed during turning of the vehicle. A damper looks or unlocks the rear axle. A controller has a memory that stores a first value and a second value of an angular velocity rate that represents an angular velocity per unit time. The controller activates or deactivates the damper. The controller activates the damper to lock the rear axle when the angular velocity rate is greater than the first value. The controller deactivates the damper to unlock the rear axle when the angular velocity rate is kept smaller than the second value for a predetermined time period after the angular velocity rate has become smaller than the second value.

Abstract: A valve arrangement using at least two piston slide valves flanged in series with their valve housings. The number of required line holes are reduced as are the number of sealing sites.

Abstract: A hydraulic valve arrangement with locking and floating function, with a control valve (9), which, for two operating positions (11, 12) connects one motor connection (A) with a pump connection and a second motor connection (B) with a tank connection and vice versa, in a floating position (13) connects both motor connections (A, B) with the tank connection and in a locking position (10) separates both motor connections (A, B) from the pump and tank connections. Further, there are two closing valves (16, 17), each being connected between the control valve (9) and a motor connection (A, B) and each having a piston loaded by a spring and limiting a spring chamber, the spring chambers being pressure releasable. Characteristic of this valve arrangement is that lifting valves (18, 19) are provided for the pressure release, which valves are operated by a control pressure depending on the position of the control valve (9). This improves the operating reliability.

Abstract: The present invention provides a hydraulic controller comprising: a plurality of switching spools; a plurality of cylinder ports of a switching valve; a compressed oil passage common to the switching valves having an intermediate chambers, at least a check valve in correspondence with at least a part of said switching spools, and said check valve being positioned between said intermediate chambers and said cylinder ports, so that said switching spools being positioned in a neutral position to close said passage and also being movable to adjust opening degree of said passage, wherein auxiliary ports are provided between the cylinder ports and a tank line; flow rate adjusters are also provided between the auxiliary ports and the tank line for adjusting an opening degree of the passage; pressure detectors are provided in the switching valves for detecting pressures of oils in the intermediate chambers; a maximum pressure selector operatively linked to said pressure detectors for selecting a maximum pressure from

Abstract: In a hydraulic control device for the direction control of at least one highest hydraulic pressure hydro-motor with working pressures above about 400 bar from a pressure source the hydro-motor is connectable via at least one consumer line and two leakage-free black/white directional seated valves selectively with said pressure source or a return line, within in said consumer line a load holding blocking valve is provided in leakage-free seated valve design and where in-between said pressure source and said return line a 2/2 idling or shunting directional seated valve having a hydraulic actuation is provided which in its blocking position is leakage-free from the pressure source towards said return line and in each switching position is leakage-free between said hydraulic actuation and said return line, and wherein said hydraulic actuation of said idling directional seated valve between said load holding blocking valve and one of said directional seated valves is connected with said consumer line.

Abstract: Thick matter and solids are conveyed together and substantially continuously through a conveyor pipeline. The thick matter is forced by a conveyor piston driven by a piston pump from a feed container into a conveyer cylinder. A forward face of the piston has a cutting crown with a cutting edge cooperating with an annular cutting ring to cut off solids projecting beyond an inlet in the conveyer pipeline.

Abstract: A speed controller has a pilot check valve having a first body which has a first fluid inlet/outlet port defined in an end thereof and a pilot port defined in an opposite end thereof. A flow control valve has a second body integral with the first body. A pipe joint has a third body which has a second fluid inlet/outlet port defined in an end thereof and, the third body being integral with the second body. A flow adjustment screw is disposed in the flow control valve and extends into a fluid passage which interconnects the first fluid inlet/outlet port and the second fluid inlet/outlet port, for adjusting a rate of flow of a fluid under pressure in the fluid passage. A valve body is disposed in the pilot check valve for opening a fluid passage which interconnects the first fluid inlet/outlet port and the second fluid inlet/outlet port in response to a pilot fluid pressure supplied from the pilot port.

Abstract: A solenoid-actuated zero-leakage fail-safe three-position poppet-style four-way hydraulic directional control valve includes an arrangement whereby the inlet pressure P is connected to the inlet ports of first and second normally closed 2-way poppet solenoid valves. The outlets of first and second poppet solenoid valves are connected to the A and B load ports, respectively. The A and B ports are respectively connected to the checked port of first and second pilot-operated check valves (POCVs) whose outlets are connected to the tank port T. The pilot ports of the POCVs are cross connected from A to B and from B to A. When the solenoid for the first poppet solenoid valve is energized, the first poppet solenoid valve opens, admitting pressure to port A. Pressure is blocked to the tank port by the first POCV. Simultaneously, the pilot pressure from the A-line opens the second POCV, thereby connecting the B port to tank. If power fails, pressure is maintained in the A-line and the B-line remains connected to tank.

Abstract: A pneumatic piston-cylinder apparatus of single acting type which performs a working stroke in one working direction, and is returned to its initial position without any external supply of compressed air comprising a cylinder part with cylinder jacket (1), a front end (2), a rear end (3), and a piston (5) which is reciprocatable in the cylinder. Connected to the rear end (3) is a supply of compressed air and within the cylinder is a return channel (10) used for draining the air on the unloading side of the piston.

Abstract: The hydraulic control system disclosed herein employs a pair of combination poppet/spool valves to control the operation of a hydraulic cylinder driven from a bidirectional pump. Flow introduced through the source port of one valve lifts the poppet of the other valve on its way to one side of the cylinder which in turn opens a throttling port to modulate return flow from the other side of the cylinder.