Abstract: An example hydraulic tool includes: a fluid reservoir; a pump; an electric motor; a cylinder; a piston; a first trigger button; a second trigger button; and a controller configured to perform operations comprising: receiving a first signal when the first trigger button is triggered, responsively, causing the electric motor to rotate in a first rotational direction, thereby: (i) causing the pump to provide fluid to the cylinder, and (ii) causing the piston to move in a first linear direction, thereafter, receiving a second signal when the second trigger button is triggered, and responsively to the second signal, causing the electric motor to rotate in a second rotational direction opposite the first rotational direction, thereby: (i) opening a fluid path from the cylinder to the fluid reservoir, and (ii) causing the piston to move in a second linear direction opposite the first linear direction.

Abstract: Embodiments of the invention provide a hydraulic tool including a hydraulic actuator cylinder, a piston, a fluid reservoir, a pump, a regeneration check valve, and a pilot-operated valve. The regeneration check valve is disposed in a regenerative extension fluid path that fluidly couples a first and second chamber of the hydraulic actuator cylinder. The pilot-operated valve is disposed in a power extension fluid path that fluidly couples the second chamber to a fluid reservoir.

Abstract: An example hydraulic tool includes: a fluid reservoir; a pump; an electric motor; a cylinder; a piston; a first trigger button; a second trigger button; and a controller configured to perform operations comprising: receiving a first signal when the first trigger button is triggered, responsively, causing the electric motor to rotate in a first rotational direction, thereby: (i) causing the pump to provide fluid to the cylinder, and (ii) causing the piston to move in a first linear direction, thereafter, receiving a second signal when the second trigger button is triggered, and responsively to the second signal, causing the electric motor to rotate in a second rotational direction opposite the first rotational direction, thereby: (i) opening a fluid path from the cylinder to the fluid reservoir, and (ii) causing the piston to move in a second linear direction opposite the first linear direction.

Abstract: A hydraulic system includes a hydraulic valve, a load-holding valve arrangement, a flow-control valve arrangement, a working pressure sensor, a differential pressure sensor, and a speed sensor. The load-holding valve arrangement includes first and second load-holding valves connected to opposite ends of the hydraulic cylinder. The flow-control valve arrangement includes a directional flow-control valve and a hydraulic pump. The differential pressure sensor measures pressure over the load-holding valve arrangement. A desired extension or retraction speed of the hydraulic cylinder is controlled by adjusting the position of the directional flow-control valve, the first load-holding valve and the second load-holding valve based on a measured working pressure in the hydraulic system and a measured speed of the hydraulic cylinder or a differential pressure over the load-holding valve arrangement.

Abstract: The present disclosure provides a heat exchanger system for a servovalve, comprising a base comprising a supply port in fluid communication with a return port, a first passage for fluid connection to a source of cooling fluid, and a second passage in fluid communication with the return port. The system further comprises one or more pipes located over a surface of the base, the one or more pipes fluidly connected between the first passage and the second passage, such that in use cooling fluid may flow from the first passage to the second passage via the network of pipes.

Abstract: A regulating device for use with a pump that has a hydraulically adjustable displacement volume, wherein the regulating device includes an inflow port, a return flow port, an actuating port, a control port, a first control slide valve, and a second control slide valve. The first control slide valve is linearly movable with respect to a center axis, the first control slide valve defining first and second orifices, which are adjustable jointly and in opposite directions. The second control slide valve is linearly movable and defines third and fourth orifices, which are adjustable jointly and in opposite directions. The second control slide valve is accommodated in a linearly movable manner within the first control slide valve.

Abstract: A valve system for use with a cylinder having an extensible rod, includes first and second valve assemblies, each including an inlet/outlet port configured to selectively be coupled with a source of pressurized gas, a check valve biased toward a closed state and having a check valve body at least partially receivable within a first port of the cylinder, a flow control valve positioned in series between the inlet/outlet port and the check valve, and an inlet pilot port connected with the check valve for opening the check valve when supplied with pressurized gas. First and second pilot lines extend to the respective inlet pilot ports from respective outlet pilot ports of the opposite ones of the first and second valve assemblies. When pressurized gas is supplied to the inlet/outlet port of a valve assembly, pressurized gas is also supplied to the opposite inlet pilot port.

Abstract: The disclosure relates to a hydraulic driving system and a driving method for barring. The driving system comprises: three or more main drive hydraulic cylinders, which are divided into two groups to provide pulling and pushing forces to a driven impeller, each main drive hydraulic cylinder including a cylinder body and a piston rod which divides the cylinder body into a rod cavity and a godless cavity, wherein an oil line for the rod cavity and an oil line for the godless cavity of each main drive hydraulic cylinder are controlled by one control valve module; and a control device, which controls the control valve module according to wind and/or load signals, to simultaneously convert flow directions of hydraulic oil in the oil line for the rod cavity and the oil line for the godless cavity of at least one of the three or more main drive hydraulic cylinders.

Abstract: The present disclosure provides a heat exchanger system for a servovalve, comprising a base comprising a supply port in fluid communication with a return port, a first passage for fluid connection to a source of cooling fluid, and a second passage in fluid communication with the return port. The system further comprises one or more pipes located over a surface of the base, the one or more pipes fluidly connected between the first passage and the second passage, such that in use cooling fluid may flow from the first passage to the second passage via the network of pipes.

Abstract: A line rupture safeguard for a hydraulic cylinder that has a connecting line between a connection for the hydraulic cylinder and a connection for a hydraulic unit, wherein a spring-biased closure unit in the connecting line is biased in a position releasing the connecting line, and at least partially closes the connecting line when a pressure differential in the connecting line is exceeded. A movable cam follower is provided that has a curved section which interacts with the spring-biased closure unit, and whose position dictates the spring bias of the closure unit and the pressure differential for at least partially closing the closure unit.

Abstract: A work vehicle includes a pin connected to a stick boom at a location remote from a hoist boom. The pin has an envelope throughout which the pin is moveable by the hoist boom and the stick boom. A controller can receive a first signal from a hoist boom sensor, receive a second signal from a stick boom sensor, and receive input from a user interface. The controller can inhibit movement of the pin to at least one portion of the envelope, thereby permitting movement throughout a movement envelope, the movement envelope being smaller than the envelope. The controller can operate in a first operation mode when the pin is spaced from a perimeter of the movement envelope and can operate in a second operation mode when the pin is proximate the perimeter of the movement envelope.

Abstract: A cooling flow circuit is provided and includes a main line having first and second sections ported to piston extend and return sides of the gas turbine engine actuator, respectively, an orifice disposed along the main line between the first and second sections, a bypass line and a bypass valve. The bypass line is fluidly coupled to the first and second sections at opposite ends thereof, respectively. The bypass valve is disposed along the bypass line between the opposite ends thereof. The bypass valve has a variable flow area which is responsive to a pressure differential between the first and second sections.

Abstract: A work machine has a connecting valve which is positioned fluidly between a hoist actuator and a stick actuator to permit fluid flow between the hoist actuator and the stick actuator when the connecting valve is open. When the connecting valve is closed, fluid flow is inhibited between the hoist actuator and the stick actuator. A controller can receive information from a hoist boom position sensor and a stick boom position sensor, the controller can receive input from a user interface, and the controller can communicate signals to the hoist actuator and the stick actuator based upon the information from the hoist boom position sensor and the stick boom position sensor, and the input from the user interface.

Abstract: A novel design of a hydraulic steering arrangement for a thruster of a marine vessel is specifically designed for thrusters intended to operate in an arctic environment where ice is present. To meet the arctic demands the steering arrangement is provided with a cross-over safety block arranged close to the hydraulic steering motor for absorbing the torque subjected to the thruster by ice for instance.

Abstract: A differential cylinder for a hydromechanical drive for actuating an electrical switch, for example a high-voltage switch, is disclosed which includes a first pressure region for applying a working pressure, a second pressure region, and a piston which is capable of moving in a movement region and which is movable depending on a pressure difference between the first and second pressure region. A damping device is provided which, in the event of a movement of the piston in the direction of the second pressure region, provides damping with respect to the movement of the piston in a section of the movement region, wherein the damping is adjustable.

Abstract: A system can include one or more valve arrangements with a working chamber to receive a working fluid at a first pressure, and a control chamber to receive fluid at a second pressure. A dynamic seal can be disposed on a land of a valve element. The valve arrangement may include a sleeve against which the dynamic seal is slidably engaged. The valve element may include a check stem. A pressure compensating system may be in communication with bores formed in with the valve element. A pressure system to monitor dynamic seal wear may be in communication with the control chamber of the valve arrangement.

Abstract: The invention relates to a proportional directional control valve for controlling a hydraulic consumer, having a housing with a pressure port, a tank port, and first and second working ports. A control element is movably mounted in the housing. A single actuator is provided for moving the control element, which, in dependence on its position relative to the housing, enables different flow paths between the ports. The control element, starting from a first switching position in which both working ports are connected to the tank port, is movable by the actuator via a second switching position that follows the first switching position, to a third switching position that follows the second switching position. It is possible, by moving the control element from the first switching position into the third switching position, to successively disconnect the two working ports from the tank port and connect them to the pressure port.

Abstract: The present invention provides a flushing circuit for a hydraulic cylinder drive circuit, by which the flushing of the circuit is conducted while protecting precision apparatuses of a control valve unit, because the flushing of a reciprocating hydraulic cylinder and its drive circuit is conducted while bypassing the control valve unit. In a hydraulic oil supply/discharge circuit connecting a tank of hydraulic oil, a hydraulic pump generating pressurized hydraulic oil, and a hydraulic cylinder with one another, a control valve unit in which at least a direction switching valve is provided in the vicinity of the hydraulic pump and the oil tank and a multifunction valve having a bypass circuit in the vicinity of the hydraulic cylinder are provided, and a bypass circuit bypassing the control valve unit is provided to branch from a hydraulic oil supply/discharge circuit between the multifunction valve and the control valve unit.

Abstract: A pump includes an outflow channel configured for discharging fluid out of the pump. The outlet area thereof is formed by a throttle. The throttle includes a spring element configured to change the size of the outlet area of the outflow channel.

Abstract: An improved double check valve for a construction machine is provided, which can greatly reduce noise and hunting phenomenon by making check valves open and close within a predetermined time difference to correspond to pressure drops that occur due to an external load when a dozer blade working device is operated.

Abstract: A device for cutting shock damping of work machines, for example, for presses and stamping or nibbling machines, and a method for cutting shock damping. Embodiments of the invention are employed in work machines that have a machine frame and a working drive for moving a working tool along a working direction, and in which the machine frame is deformed elastically by a working force exerted by the working drive for machining a workpiece. The working drive provides a control variable for determining the working force of the work machine.

Abstract: An apparatus for lifting motor vehicles includes a first lifting device which is movable in a vertical direction and which is suitable for supporting a first region of the motor vehicle to be lifted, and a second lifting device which is arranged at a distance from the first lifting device and which is suitable for supporting a second region of the motor vehicle to be lifted. A first supply line supplies an hydraulic medium to the first lifting device, and with a second supply line supplies an hydraulic medium to the second lifting device.

Abstract: A hydraulic load control valve (10) accommodated between a hand valve (H) and a hydraulic engine (D) has got at least one proportional load control valve (E), controlled by the pump pressure independent of the flow of hydraulic fluid to the engine. The flow to the engine (D) flows via a non-return valve (12), that is prestressed to open at a pump pressure above the upper limit before a given pressure interval, within which the load control valve (E) is adjusted between completely closed and completely open position of the pump pressure.

Abstract: A valve member of a pressure relief valve has a shaft portion, a pressure receiving portion, and a guide portion, wherein the valve member is axially movable in a fuel return passage. When a forward end of the shaft portion is seated on a valve seta, the fuel return passage is closed, while the shaft portion is separated from the valve seat the fuel return passage is opened. A notched portion is formed at an outer wall of the guide portion to thereby form an outer-surface passage. A fuel inlet port is formed in the valve member for communicating a fuel inlet chamber to the fuel return passage at a downstream side of the valve member.

Abstract: A hydraulic drive system realizes a jack-up operation without arrangement of a flow rate control valve and center bypass selector valve. The hydraulic drive system has first and second hydraulic pumps, first and second directional control valves for controlling boom cylinders, a third directional control valve for controlling the boom cylinders, and a third hydraulic pump for feeding pressure oil to the third directional control valve. A jack-up selector valve has a second select position where, when a pressure in bottom chambers of the boom cylinders is not higher than a predetermined pressure, feeding of pressure oil, which is delivered from the first hydraulic pump and second hydraulic pump, to rod chambers of the boom cylinders, is held permissible in association with switching of the second directional control valve and third directional control valve by a manipulation of a control device.

Abstract: A weld cylinder having a single piston arrangement is provided. The cylinder has a movable retract piston assembly with the piston arranged within the retract piston assembly. The piston supports a rod that is movable between home, intermediate, work, and advanced work positions. The rod moves rapidly from the home position to the intermediate position however, the rod moves more slowly from the intermediate position to the work position to reduce the impact force. A cushion chamber slowly exhausts through a pre-orifice and a hole in the cushion valve while an isolator is in an open position. Once the cushion valve opens in response to a retract-forward pressure on the cushion valve, the cushion chamber exhausts rapidly so that weld force increases rapidly to minimize increases in cycle time. Advance of a retract piston assembly is also cushioned. A weld-forward port is no longer provided on a cylinder barrel.

Abstract: A lock valve includes a lock valve body having a bore with a valve spool reciprocatingly received therein. There is a check valve adjacent each end of the bore. Each of the check valves has a check valve member facing the bore and resiliently biased towards a valve seat at each end of the bore. A pressure relief port communicates with the bore near the center thereof and between lands of the valve spool. A pair of spaced-apart grooves are disposed within the spool valve bore. Each groove permits fluid communication past a land of the valve spool when the valve spool is displaced towards one end of the bore by fluid pressure applied to other end of the bore so as to unseat the check valve member adjacent to the one end to the bore and allow pressurized fluid to pass from the one end of the bore, through the groove, and into the relief port.

Abstract: Provided is a hydraulic drive including a double-acting work cylinder with a piston having a first working surface effective in a retracting direction and a second working surface effective in an extending direction, wherein the first working surface delimits a first pressure chamber and the second working surface delimits a second pressure chamber, at least two different pressures being applicable to at least one of the first working surface and the second working surface for retracting or extending the piston into and out of the work cylinder, an actuator unit which optionally enables a throttled return flow of a hydraulic medium from the first pressure chamber delimited by the first working surface, and control means for triggering the actuator unit in such a way prior to a sudden acceleration of the piston due to a sudden force release.

Abstract: A device (100, 200, 200bis, 300, 300bis) for controlling a pilot pressure signal of hydraulic valves (3), for controlling the handling of gravitational loads (M), operating between two pilot lines (108, 109, 208, 209, 308, 309) between the valve (3) and a cylinder (1) adapted to sustain the load (M). The device (100, 200, 200bis, 300, 300bis) is a two-way and two-position valve for the communication between the cylinder stem-side pilot line (5) and the valve-side line (3) and is a valve which can take an open position and a partialized position, or anyway it never takes a closed position. The device (100, 200, 200bis, 300, 300bis) can take a position so that the fluid passage between the pilot lines (108, 109, 208, 209, 308, 309) is never completely closed.

Abstract: An actuation system includes a pump assembly configured to form a pump chamber, an actuator having first and second chambers and a movable member and configured to convert pressures applied to the first and second chambers into a movement of the movable member, and a valve section. The valve section has a plurality of positions set by a controller, and the plurality of positions includes a first position in which the valve section opens the first flow path and closes the second flow path, a second position in which the valve section closes the first flow path and opens the second flow path, and a neutral position in which the valve section closes the first and second flow paths.

Abstract: A valve assembly includes a check valve element in an output chamber. The check valve element opens to permit forward flow of fluid under pressure in the output chamber from an input port to an output port. The check valve element closes to block back flow of fluid under pressure in the output chamber from the output port toward the input port. The back flow of fluid under pressure exerts a closing force upon the check valve element from within the output chamber. A counter force generating element, or pilot element, communicates with the valve element, to selectively open the valve, even in the presence of back flow pressure. The counter force generating element may apply a counter force to the check valve element, which urges the valve element toward the opened condition. The counter force may be less than the closing force, so the check valve element remains closed.

Abstract: A fluid cylinder actuator assembly is provided. The assembly includes a cylinder tube and a cushion control needle assembly. The cushion control needle assembly is configured to extend into the fluid cylinder actuator assembly to control fluid that exits the cylinder tube and comprises: a threaded cushion control differential screw that selectively screws into a retainer having corresponding threads; a control needle that includes a stem selectively extendable through a bore in the retainer opposite of the cushion control differential screw; wherein the stem of the control needle is engageable with a threaded bore inside the cushion control differential screw that is complimentary to the threads formed on the stem so that rotating the threaded cushion control differential screw will selectively extend or retract the control needle back and forth; and wherein threads of the threaded cushion control differential screw is different than the threads in its threaded bore.

Abstract: A control system for a reciprocating device which includes a switching valve for directing fluid supply under pressure to one of two drive lines in an alternating manner, means for alternating the switching valve, and an exhaust circuit including and exhaust outlet, a first flow restrictor disposed between one drive line and the exhaust outlet, and a second flow restrictor disposed between the other drive line and the exhaust outlet. The system may include a selection valve for alternately connecting one of two drivelines to the exhaust outlet.

Abstract: A valve member of a pressure relief valve has a shaft portion, a pressure receiving portion, and a guide portion, wherein the valve member is axially movable in a fuel return passage. When a forward end of the shaft portion is seated on a valve seta, the fuel return passage is closed, while the shaft portion is separated from the valve seat the fuel return passage is opened. A notched portion is formed at an outer wall of the guide portion to thereby form an outer-surface passage. A fuel inlet port is formed in the valve member for communicating a fuel inlet chamber to the fuel return passage at a downstream side of the valve member.

Abstract: A line connects the tractor hydraulic power beyond supply to the pressure reduction valve that is connected to the implement cylinder ends and automatically controls implement down pressure. Fluid under pressure is supplied from a line independently of the tractor selective control valve during automatic down pressure mode operation, the selective control valve can be positioned in a float mode when the down force circuit is controlling implement down pressure. The circuit eliminates a stall signal from the selective control valve to the hydraulic pump that otherwise would cause the pump to rise to the high, heat-producing stall pressure if the selective control valve operated in an active pressure mode.

Abstract: Faster shifting operation and reduced shift shock in response to a braking operation during a lift-foot-up shifting may be achieved when an automatic transmission is controlled by a method for compensating a hydraulic pressure that includes: determining whether a lift-foot-up shifting of the automatic transmission is under control; calculating a vehicle speed of a vehicle; calculating a deceleration rate of the vehicle; calculating a compensation hydraulic pressure to be applied to a friction member of the transmission, based on the deceleration rate; calculating a on-coming pressure based on the calculated compensation hydraulic pressure; and applying the calculated on-coming pressure to the friction member.

Abstract: A valve system includes a load holding valve, a feed balancing valve, and a fast feed differential valve. The load holding valve may be in fluid communication with the load holding valve. The fast feed differential valve is configured to move between an engaged state and a disengaged state. In the engaged state the fast feed differential valve fluidly couples a ring side of a feed cylinder, the load holding valve, and a piston side of the feed cylinder to allow fluid to flow from the ring side to the piston side.

Abstract: A tool coupler assembly for a machine is disclosed. The tool coupler assembly may have a coupler frame, a first latch, a second latch, and a hydraulic actuator connected to move the second latch relative to the first latch and the coupler frame. The hydraulic actuator may have a first chamber, a second chamber, and a pressure valve with a check element movable to allow a flow of fluid into the first chamber based on a pressure of fluid in the first chamber, and a pressure regulating element movable to allow a flow of fluid out of the first chamber based on a pressure of fluid in the second chamber. The tool coupler assembly may additionally have a first pilot passage configured to communicate fluid from the second chamber with the pressure-regulating element, and a second pilot passage configured to communicate fluid from the first chamber with the pressure-regulating element.

Abstract: The invention concerns a hydraulic valve arrangement (1) having at least two working connections (A, B), a check valve (5, 6) being allocated to each working connection (A, B), and a pressure relief valve (7, 8) being allocated to each check valve (5, 6), each pressure relief valve (7, 8) being connected to a control pressure passage (17, 18). The valve arrangement shall ensure a reliable, pressure-less lowering, also in connection with single-actuated consumers, and further enable a pressure-less float position. For this purpose, the check valves (5, 6) can be opened by means of tappets (20, 21), whose sides facing away from the check valves (5, 6) are ending in a pressure chamber (22), which is connected to the control pressure passage (17, 18) of one of the pressure relief valves (7, 8).

Abstract: A solar panel carrier T is provided at a sub-structure U such that it can be rotated and tilted by means of hydrostatic rotation and tilt motors M, M?. In an electrohydraulic adjusting device for the solar panel carrier T a motor pump aggregate 8 is connected to the hydrostatic motors. Within working lines A, B of the tilt hydrostatic motor M at least one tilt control system K is provided, which comprises valve components and a pilot pressure circuit. The tilt control system K comprises pressure actuated blocking valves or load holding valves LHVA, LHVB. For automatically adjusting a protected position S of the carrier T a suction line N is provided at the side of the hydrostatic tilt motor facing to the blocking valves or load holding valves. The suction line N is surveyed by a monitoring solenoid 18 and is opened depending on initial pressure conditions in case of switching off the electric power and/or in case of an electric breakdown.

Abstract: The present invention relates to an apparatus operating a hydraulic actuator for valve, which can manually operate the hydraulic actuator for opening and closing the valve by which a flow rate is adjusted. According to the present invention, by manually operating the hydraulic actuator for opening and closing the valve, there is an advantage of manually opening and closing the valve and thus easily adjusting a flow rate of fluid flowing in a pipe, even when power is cut off. Further, according to the present invention, the hydraulic actuator for opening and closing the valve can be selectively connected with a hydraulic power pack so as to automatically open and close the valve using the hydraulic power pack according to a user's selection, or which can manually open and close the valve.

Abstract: A system and method for performing a floating function in an earthmoving implement of an earthmoving machine without physically connecting chambers within a hydraulic actuator that is adapted to raise and lower the earthmoving implement. The system includes a device for delivering a pressurized fluid to and receiving pressurized fluid from the actuator, a valve for compensating for differences in volume between chambers of the actuator, and an electronic control circuit that includes electronic sensors for sensing the pressures in the chambers of the actuator, and a controller for receiving outputs of the sensors. The controller calculates an amount of the pressurized fluid that, when delivered to or received from the actuator, achieves a substantially constant pressures in the chambers of the actuator and enables the earthmoving implement to float regardless of motion of the actuator.

Abstract: A weld cylinder having a dual piston arrangement is provided. The cylinder has a movable retract piston assembly with the piston arranged within the retract piston assembly. The piston supports a rod that is movable between home, intermediate, work, and advanced work positions. The rod moves rapidly from the home position to the intermediate position however, the rod moves more slowly from the intermediate position to the work position to reduce the impact force. A cushion chamber slowly exhausts through a hole in the cushion valve while an isolator is in an open position. Once the cushion valve opens in response to a weld-forward pressure on the cushion valve, the cushion chamber exhausts rapidly so that weld force increases rapidly to minimize increases in cycle time.

Abstract: A weld cylinder having a single piston arrangement is provided. The cylinder has a movable retract piston assembly with the piston arranged within the retract piston assembly. The piston supports a rod that is movable between home, intermediate, work, and advanced work positions. The rod moves rapidly from the home position to the intermediate position however, the rod moves more slowly from the intermediate position to the work position to reduce the impact force. A cushion chamber slowly exhausts through a hole in the cushion valve while an isolator is in an open position. Once the cushion valve opens in response to a weld-forward pressure on the cushion valve, the cushion chamber exhausts rapidly so that weld force increases rapidly to minimize increases in cycle time.

Abstract: A tube defines a cavity. Normally-open fitting (2) and normally-closed fitting (3) are respectively fitted into the tube to form ports (34),(35) having seats (40),(13). A body secured to fitting (3) defines a chamber (26) to which port (35) leads. Body (4) defines holes (27),(30) leading into chamber (26). A solenoid assembly (6) is slidable within chamber (26), includes a coil, segregates chamber (26) to chambers (7),(29) which communicate respectively with holes (27),(30) and defines a chamber (16), a seat (18), a seal (14) and an orifice (33) leading between seat (18) and seat (13). A rod-piston assembly includes a rod (37) attached to: assembly (6), sealably passing through body (4) into cavity and preventing gas communication between cavity and chamber (7); and a piston with a seal (39). A magnetic rod (15) slides within chamber (16). Spring (17) urges rod (15) towards seat (18) to seal orifice (33). Spring (12) urges assembly (6) towards seat (13) to seal port (35).

Abstract: A system operates a hydraulic actuator, such as a cylinder, in one of several modes that include powered extension and retraction, self-powering regeneration modes in which fluid exhausting from one cylinder chamber is routed into the other cylinder chamber, and cross function regeneration modes wherein the fluid exhausted from one actuator is routed in the supply conduit to power a different actuator. A controller determines which modes are viable based on existing system conditions and selects from among the viable available modes. That determination is a function of the desired velocity for the actuator, the hydraulic load on the actuator, and pressures in the supply and return hydraulic conduits. The system also can recover potential or kinetic energy through pressure intensification which recovered energy can be used to power another simultaneously active hydraulic function or to drive the prime mover via an over-center variable pump/motor.

Abstract: The invention relates to a valve 120, especially a check valve, for hydraulic plungers (3) of shield-type support frames in underground mining with a valve housing 121 and a switchable valve insert received therein, connections 126-129 for high pressure lines connected to the cylinder chamber and/or the annular space of the hydraulic cylinder 3, and at least one connection 30 for an additional unit such as a pressure relief valve, a pressure sensor, and/or a pressure display. The valve housing 121 can be mounted to the hydraulic cylinder 3, and in the mounting stage, the connections 125-129 on the valve housing 121 extend axially parallel to the axis of the hydraulic plunger 3. According to an advantageous further embodiment, the valve housing can be provided with at least one fastening means for an extension housing 40 that can be mounted in a releasable manner to at least one side wall 22B thereof for additional hydraulic functions of the shield-type support frame (see FIG. 2).

Abstract: A hydraulic metalworking machine for working a work piece has a stand having a frame, a center portion which moves along a vertical path within the frame, and at least one hydraulic cylinder unit mounted in said stand. The machine has a high speed mode, a force mode, and a retract mode. During the high speed mode fluid flows into the power cylinder and extends the rod out at a high speed. During the force mode the rod extends out at a slower speed but under higher pressure than the high speed mode. During the retract mode fluid is moved into the cylinder rod end and fluid in the cylinder base end is removed.

Abstract: The invention relates to a releasable non-return valve, in which a connection between a working chamber and a connector chamber may be closed by a non-return piston and opened by the opening movement of a release piston which may be pressurized with a release pressure. The non-return piston, discharge piston and release piston are arranged concentric to each other with the release shaft in the common valve axis. The valve has a cartridge embodiment with a non-return valve cartridge which may be inserted in the valve housing and a discharge valve cartridge independent of the non-return valve cartridge. The release shaft extends through the non-return piston with a sliding seal and engages behind the piston base by means of a stepped diameter for opening. The discharge piston is pressure compensated on both sides by pressurization with the working pressure.

Abstract: The invention concerns a hydraulic valve arrangement (1) with a control valve module (2) comprising a supply connection arrangement with a high-pressure connection (P) and a low-pressure connection (T) and a working connection arrangement with two working connections (A, B) as well as a control valve (3) between the supply connection arrangement and the working connection arrangement. It is endeavored to improve the control behavior of the valve arrangement. For this purpose. it is ensured that the control valve module (2) has a return compensation valve (15, 16) between the control valve (3) and at least one working connection (A, B).