Abstract: A hydraulic power drive unit (PDU) for a transmission system includes a hydraulic motor for converting hydraulic pressure into torque and rotation; a hydraulic brake system for applying a braking force to the hydraulic motor to prevent rotation of the hydraulic motor, wherein the hydraulic brake system is biased to apply the braking force to the hydraulic motor to prevent rotation of the hydraulic motor, and configured to remove the braking force in response to a supply of hydraulic fluid; and a hydraulic circuit for supplying a flow of hydraulic fluid to the hydraulic motor to pressurise and thereby operate the hydraulic motor and for supplying hydraulic fluid to the hydraulic brake system to pressurise the hydraulic brake system and thereby remove the braking force; wherein the hydraulic circuit comprises a brake supply line for supplying the hydraulic fluid to the hydraulic brake system.

Abstract: An arrangement includes a field device with an on/off valve, a pneumatic actuator that moves the on/off valve, when applied with compressed air, into one on/off position and when ventilated into the other on/off position, a magnetic valve that applies compressed air to the actuator during electric actuation and ventilates the actuator during non-actuation and a function monitoring device that detects at least one parameter that refers to the movement of the on/off valve, where the function monitoring device includes a magnetic field sensor detecting changes to a magnetic field, where the magnetic field sensor is arranged in the region of the magnetic valve and generates a signal awakening the function monitoring device to detect the at least one parameter.

Abstract: Disclosed embodiments include travel motor hydraulic circuits for controlling the provision of hydraulic fluid to a travel motor. The travel motor hydraulic circuits include a counterbalance valve configured to block the flow of hydraulic fluid when in a neutral position to prevent unintended movement of a power machine, and an anti-cavitation valve configured to direct flow of hydraulic fluid back to the travel motor to prevent cavitation.

Abstract: A device for choking a fluid flow includes a pot-like base body, in the base of which a first passage opening is arranged, and a closing body guided axially moveably in the pot-like base body against a spring force of a spring element and having a second passage opening that forms a static choke point with a predefined fixed opening cross section. The closing body in combination with the spring element and the first passage opening forms a dynamic choke point with a dynamic opening cross section that is variably adjustable depending on a pressure difference.

Abstract: A fluid pressure control device includes a load holding mechanism that is configured to hold the load pressure of the load side pressure chamber. The load holding mechanism includes a switching valve having a communication passage configured to be blocked from the third pressure chamber by the second land section in a case where the spool is closed, and providing communicate between the second supply port and the discharge port in accordance with the movement of the spool in the valve opening direction. In a case where the spool is moved in the valve opening direction, at the same time when or after the second supply port communicates with the discharge port via the communication passage, the first land section is brought into sliding contact with the annular projecting section and the first supply port and the discharge port are blocked from each other.

Abstract: In conventional load-sense systems, there is a delay between a hydraulic function being impeded by an external force and further motion of the function. This is typically due to cavitation on the low pressure side of the pump. Electro-hydraulic systems, however, typically respond very quickly because the low pressure side of the pump may be pressurized because the low-pressure side of the actuator may feed directly to the pump rather than going to tank. Thus, an operator cannot as easily rely on feedback for when a function has encountered an external load. This may result in loss of vehicle traction or other drawbacks. Therefore, provided is a system and method for mimicking a load-sense system's responsiveness using an electro-hydrostatic system via an induced passive or active time-delay.

Abstract: A fluid pressure control device includes a switching valve that operates in conjunction with a control valve by a pilot pressure to switch an operation of an operated check valve. The switching valve includes a spool that moves according to the pilot pressure of a pilot chamber, and a piston that is accommodated in the pilot chamber and imparts a thrust force to the spool upon receiving the pilot pressure. The piston includes a first piston that is slidingly accommodated in the pilot chamber and is acted upon by the pilot pressure, and a second piston whose distal end faces the spool and is inserted into an accommodating hole formed in the first piston. A spherical protrusion is provided on a center of either one of a bottom surface of the accommodating hole of the first piston and a back surface of the second piston.

Abstract: An assembly of valve sections includes an inlet section, an outlet section, a working section, and a working section. The working section is a conventional pressure compensated working section. The working section includes a directional control valve, a pressure compensator valve, and a pressure limiter valve. The valves are of integral construction, such that each is an essential part to complete the other. The pressure compensator valve includes a pressure compensator spool movable between an opened position and a closed position in response to a pressure differential across the spool. The pressure limiter valve includes a pressure limiter spool that moves to an open position to change the pressure differential and close the pressure compensator valve when a selected limit pressure is reached.

Abstract: A valve arrangement is provided for selectively connecting a source of fluid pressure to a consumer in order to actuate the consumer in a predetermined direction. The valve arrangement utilizes a valve cone arranged in the valve body which connects the valve ports with each other when the valve cone is in its open position, and is actuated by a holding force which is greater than the force acting on the pressurized fluid side of the valve cone and dependent on the medium pressure in the input port.

Abstract: Disclosed is a boom cylinder control circuit for a construction machine including a boom cylinder having an ascending-side chamber and a descending-side chamber. The boom cylinder control circuit includes: a first floating chamber with first and second input ports connected to the descending-side chamber and the ascending-side chamber, respectively, at one side, and first and second output ports connected with the drain tank, at the other side, and is switched to selectively connect the first and second input ports to the first and second output ports in accordance with an operational signal of the floating selection operation part; and a second floating valve of which one side is connected to the first output port and the other side is connected to the drain tank to selectively connect the first output port with the drain tank in accordance with the operational signal.

Abstract: Disclosed is a slow-acting ON/OFF valve which includes a valve-opening pressure chamber that makes an actuating member (which actuates a valve body that comes into contact with and moves away from a valve seat to close and open a flow passage) move in a valve-opening direction against a spring biasing force in a valve-closing direction, and supplies air to the valve-opening pressure chamber, in minute increments, via a flow rate regulation valve. In this slow-acting ON/OFF valve, the dead time from the receipt of a valve-opening signal to the commencement of a valve-opening operation is short. A manifold is provided independently of the valve-opening pressure chamber.

Abstract: A fluid control valve wherein a main valve body includes: a high-pressure passage providing communication between a suction port and a sleeve in which a spool is fitted; a tank passage providing communication between a discharge port and the sleeve; a lift lock poppet located between the sleeve and a cylinder port and assuming an open position for providing communication between the sleeve and the cylinder port; a hydraulic fluid discharge passage providing communication between a back-pressure chamber provided within the lift lock poppet and the sleeve; a hydraulic fluid delivery passage located between the sleeve and the lift lock poppet; a cylinder passage located between the lift lock poppet and the cylinder port that communicates with the hydraulic fluid delivery passage when the lift lock poppet is in the open position, and a communication passage providing communication between the hydraulic fluid discharge passage and the hydraulic fluid delivery passage.

Abstract: A pair of supply/drain pipes continuous with an actuator are respectively communicable with a pair of oil sumps respectively through an intermediation of a pair of extended paths. The pair of oil sumps is formed in a switch-spool insertion hole and enter a neutral state or a state of being selectively communicated with any one of respective pressure-oil paths and respective oil-return paths. A non-leak valve is provided over respective connection portions and between the pair of supply/drain pipes and the pair of extended paths. The non-leak valve is opened when an operation of a pump is started, is maintained to be opened during the operation of the pump, and is closed when the pump is out of operation.

Abstract: A hydraulic soft-start system includes a first flow valve in fluid communication with a pressure source and an inlet of a motor. A first restricting orifice is disposed between the first valve and the inlet. A second flow valve is in fluid communication with the first valve and the inlet. A pilot for actuating the second valve is in fluid communication with the inlet. A second restricting orifice is disposed between the pilot and the inlet. Upon actuation of the first valve, a first flow is passed from the pressure source via the first orifice to the inlet, placing the motor in a partially-actuated state. The second valve being actuated after a threshold pressure of the pilot is reached allowing a second flow to pass from the pressure source to the inlet. The second flow being higher than the first flow, thereby placing the motor in a fully-actuated state.

Abstract: A load sense connection is provided between the implement rockshaft cylinders and the load-sensed power source. However, to avoid tractor starting difficulty, a valve structure is provided in the power beyond fluid line to keep the fluid line closed when starting the tractor. This valve structure provides a hydraulic latching function that allows the load-sensed power source to be activated and deactivated depending on the SCV function. The load-sensed power source is activated when the rockshaft cylinder(s) is fully extended and remains activated or latched when the SCV is returned to neutral. The load-sensed power source is deactivated or unlatched when the rockshaft cylinder is retracted.

Abstract: The invention concerns a hydraulic valve arrangement (1) with a supply connection arrangement comprising a high-pressure connection (P) and a low-pressure connection (T), a working connection arrangement comprising two working connections (A, B), which can be connected to a motor (4), a directional valve arrangement (5) located between the supply connection arrangement (P, T) and the working connection arrangement (A, B), and a compensation valve (15) acted upon in a first activation direction by a pressure in a first pressure chamber (33), which is connected to a load-sensing pipe (LS), and, if required, by a spring (32), and in a second activation direction opposite to the first activation direction by a pressure downstream of the directional valve arrangement (5), said pressure acting in a second pressure chamber (34), the compensation valve (15) having an inlet (14) and an outlet (19).

Abstract: A hydraulic system has several valve sections, each having a directional valve that controls fluid flow from a pump to a hydraulic actuator. A mechanism senses a greatest pressure among the hydraulic actuators to provide a load sense pressure. One valve sections has a pressure compensation apparatus includes a pressure compensation valve that reduces fluid flow between a given directional valve and an associated hydraulic actuator in response to pressure at a control port, and a pressure regulating valve that responds to the load sense pressure and pressure in the associated hydraulic actuator by selectively applying output pressure from the pump and the load sense pressure to the control port.

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: The invention relates to the field of load sensing, flow sharing directional control valves for controlling an operating machine, such as an excavator. The directional control valve of the present invention is particularly characterized by the addition of at least one element (E4) wherein the provision of a bore (16) and the replacement of components (30), (50), (M1) with a compensator (9), having a spring (14) operating on one side thereof (9a), and a piston/load sensing signal selector (8) impart to this single element (E4) the feature of non participating in flow-rate reduction under saturation conditions, while preserving the feature of maintaining a constant flow-rate to the user, irrespective of the variation of the load.

Abstract: A holding control valve of the present invention is configured such that: a spool is configured to perform strokes by a piston configured to operate by introduction of pilot pressure and have a larger diameter than the spool; the piston is divided into a pilot piston configured to receive the pilot pressure and a relief operation piston disposed adjacent to the spool to receive pressure of relief oil discharged when a relief valve operates; and the relief oil is introduced to between the pilot piston and the relief operation piston.

Abstract: A hydraulic motor 11 is switched to a high-speed mode when pressure oil is supplied to a pressure chamber 23 of a tilt piston 17 based on the transmission of a speed signal to a high-low speed switching valve 18, and the hydraulic motor 11 is switched to a low-speed mode when pressure oil is discharged from the pressure chamber 23 of the tilt piston 17. A first braking purpose speed changing mechanism 13 operates so as to discharge pressure oil from the pressure chamber 23 of the tilt piston 17 when the pressure of pressure oil between a counterbalance valve 15 and a direction changeover valve 103 becomes equal to a tank pressure. Therefore, it is possible to provide a variable hydraulic motor driving device which is capable of preventing braking operation from being excessively long and also capable of preventing a large shock from occurring at a time of stoppage due to a large braking force generated from an early stage of braking operation.

Abstract: A hydraulic control apparatus 1 includes a switch valve 11, a valve support chamber 35, a flow control valve 12 movable within the valve support chamber 35, an on-off valve 13 movable within the communication path chamber 12a, and a valve control device 14. The flow control valve 12 has a communication path chamber 12a and a back pressure chamber 12d. The on-off valve 13 is capable of opening and shutting off a communication path X between a cylinder line 32 and a switch valve line 33. A restrictor is formed between the flow control valve 12 and a wall defining the valve support chamber 35. The restrictor connects the cylinder line 32 and the communication path chamber 12a to each other. The opening degree of the restrictor is changed in correspondence with movement of the flow control valve 12.

Abstract: A hydraulic circuit for an actuator that has a piston and piston rod that will move a load in a first direction, and which can be externally loaded in an opposite direction, includes a flow compensated valve between the actuator and a control valve. When the piston in the actuator is moved in the second opposite direction under the external load and the rate of flow of fluid out of the actuator through the flow compensated valve exceeds a selected rate, an orifice is introduced in the flow path to restrict flow from the actuator.

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: A hydraulic control apparatus 1 includes a switch valve 11, an adjustment valve 12, and a valve control device 13. The adjustment valve 12 has a fluid chamber 15, a valve body 14, and a back pressure chamber 17. A restrictor is formed between the valve body 14 and a wall defining the fluid chamber 15 and connects the cylinder line 32 to the switch valve line 33. The opening degree of the restrictor changes in correspondence with movement of the valve body 14. When the switch valve 11 is located at a neutral position or a supply position, the valve control device 13 applies the fluid pressure in the cylinder line 32 to the back pressure chamber 17. When the switch valve 11 is located at a drainage position, the valve control device 13 applies a pilot pressure lower than the fluid pressure in the cylinder line 32 to the back pressure chamber 17.

Abstract: A double check valve having a floating function is disclosed, which can prevent construction equipment from overturning through intercepting of a floating function even if a signal pressure is fed to the double check valve to perform the floating function in a state that an excavator is supported by a working device (e.g. a dozer blade), i.e. in a jack-up state, on a sloping site and so on.

Abstract: The invention concerns a hydraulic valve arrangement (1) with a supply connection arrangement comprising a high-pressure connection (P) and a low-pressure connection (T), a working connection arrangement comprising two working connections (A, B), which can be connected to a motor (4), a directional valve arrangement (5) located between the supply connection arrangement (P, T) and the working connection arrangement (A, B), and a compensation valve (15) acted upon in a first activation direction by a pressure in a first pressure chamber (33), which is connected to a load-sensing pipe (LS), and, if required, by a spring (32), and in a second activation direction opposite to the first activation direction by a pressure downstream of the directional valve arrangement (5), said pressure acting in a second pressure chamber (34), the compensation valve (15) having an inlet (14) and an outlet (19).

Abstract: In an actuator control device that controls an expansion/contraction operation of a hydraulic cylinder, when a main spool 52 is switched to a discharge position for discharging working fluid in the hydraulic cylinder, a back pressure chamber 7 communicates with a tank passage 13 via a first port 14, thereby opening an operate check valve 51, and as a result, the working fluid in the hydraulic cylinder flows into a return passage 4 from an actuator port 1 and into a pilot chamber 20 through a second port 15. A pilot spool 53 is maintained in a balanced position by the pressure of the pilot chamber 20, which is caused to act by a front-rear differential pressure of a control throttle 25, and the biasing force of a spring 22 housed in a spring chamber 21, and therefore the opening area of the first port 14 is controlled to and maintained at a fixed level.

Abstract: An arrangement for controlling a swash plate of a pump includes an actuator having a piston adapted to be coupled to the swash plate wherein the separates an actuator internal chamber into first and second subchambers to which first and second valve assemblies are fluidly coupled, respectively. Each valve assembly includes a housing defining an inlet port, an outlet port, and a control port fluidly connected to one of the subchambers. A valve member slidably disposed within an interior chamber selectively moves between at least two positions to direct internal flow between the ports.

Abstract: A control valve device (1) for the control of a consumer (2), in particular of a dual-action consumer, includes a control valve (3) that controls the connection of an admission side of the consumer (2) with a pump and a return side of the consumer (2) with a reservoir. The control valve device (1) has a regeneration function by means of which the return side of the consumer (2) can be connected with the admission side of the consumer (2). The regeneration function has a short circuit device (10) located between the consumer (2) and the control valve (3) and provides a connection of the return side of the consumer (2) with the admission side of the consumer (2). For the regeneration function, the connection of the return side of the consumer (2) with the reservoir can be shut off by the control valve (3).

Abstract: A damper valve includes first and second chambers separated by a partition wall, hydraulic oil flowing from the first chamber to the second chamber via a supply path, and returning to the first chamber from the second chamber via a return path. A valve plate that is elastically deformable is urged toward a valve seat formed in the return path. The valve plate produces an elasticity restoring force so as to establish a balance between an urging force provided by an urging member and a reaction force provided by the valve plate, and is in line-contact with the valve seat when keeping the balance. The valve seat or the valve plate is formed into a conical tapered shape centered around the predetermined axis so that when the valve plate is abutted against the valve seat, an annular oil chamber is formed between the valve seat and the valve plate.

Abstract: An antagonistic fluid control system, wherein the system may comprise multiple antagonistic pressure control valves operable with a single actuator, or multiple pressure control valves operable with respective antagonistic actuators. The pressure control valves are configured to provide functional and efficiency advantages, and operate together to provide several operating or valving states. A first valving state comprises an active valving state configured to actively control the movement of the load. A second valving state comprises an inactive actuation state, wherein either the return and pressure ports of one pressure control valve are closed, or only the return ports of one pressure control valve are opened, to allow the other pressure control valve to operate in an active valving state. A third valving state comprises a passive valving state, wherein the pressure control valves are operated in a slosh mode configured to allow the load to freely move or dangle.

Abstract: A check valve system controls the flow of fluid between a spool valve and a hydraulic actuator and includes a pilot operated check valve that is controlled by a lock-out valve. The check valve has a poppet that engages and disengages a first valve seat in response to a pressure in a control chamber. The lock-out valve has an inlet connected to the control chamber, an outlet connected to an opening in the bore of the spool valve, and an second valve seat between the inlet and the outlet. A valve member that selectively engages and disengages the second valve seat and spool of the spool valve applies force to the valve member which responds by moving into engagement with the second valve seat. Thus in one position, the spool valve maintains the lock-out valve closed which traps pressure in the control chamber which tend to keep the check valve closed.

Abstract: A hydraulic control arrangement is disclosed for the control of a consumer, comprising at least one mechanically operated continuously adjustable distribution valve with a subsequent LUDV pressure compensator down the line. In order to lock the consumer the control arrangement is provided with a spring holding the pressure compensator piston in a closed position. Furthermore, the LS line carrying the highest load pressure of all consumers is connected to a reservoir by means of a flow regulator, wherein the pump control may also be relieved by the flow regulator in the sense of a reduction of the pumped volume. According to the invention, the LUDV pressure compensator is pressure-compensated by means of a nozzle through which a connection between the LS line and a portion of the pressure medium flow path downstream of the pump and upstream of the outlet of the pressure compensator is generated. Said nozzle is preferably integrated in the pressure compensator piston.

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).

Abstract: A hydraulic control apparatus is provided to prevent failure that can occur due to hunting, to elevate performance of a hydraulic control valve, and to improve operation efficiency by effectively conducting bleed off. The hydraulic control apparatus can include a first change over valve group that can include a change over valve connected with a first delivery line associated with the variable capacity pump, and arranged to have load sensing function. A second change over valve group can also be provided, and can include at least one change over valve connected with a second delivery line associated with the variable capacity pump. An open and close motion valve and a compensation valve can be configured to constitute a pressure compensation flow control means connected through the second delivery line and the second change over valve group.

Abstract: A hydraulic system for a work machine is disclosed. The hydraulic system has a reservoir configured to hold a supply of fluid and a source configured to pressurize the fluid. The hydraulic system also has a fluid actuator, a first valve, and a second valve. The first valve is configured to selectively fluidly communicate the source with the fluid actuator to facilitate movement of the fluid actuator in a first direction. The second valve is configured to selectively fluidly communicate the fluid actuator with the reservoir to facilitate movement of the fluid actuator in the first direction. The hydraulic system further has a proportional pressure compensating valve configured to control a pressure of a fluid directed between the fluid actuator and the reservoir.

Abstract: To simplify a circuit structure and a path structure in a hydraulic circuit having a pilot check valve and an overload relief valve and to reduce the size of a gear. The hydraulic circuit includes a pump port; a tank port; a first actuator port; a second actuator port; a first supply and discharge port; a second supply and discharge port; a direction changing valve; a first pilot check valve; a second pilot check valve; a first pilot path; and a first overload relief valve. The direction changing valve has a neutral position to communicate the first supply and discharge port with the tank port. The first overload relief valve is arranged in parallel with the first pilot check valve and is arranged between the first supply and discharge port and the first actuator port.

Abstract: A hydraulic control arrangement is disclosed for the load pressure independent control of a consumer, comprising a distribution valve forming an inlet metering orifice, a corresponding individual pressure compensator, a stop valve provided for each consumer connection which may be released by means of a pilot valve and an anti-cavitation valve by means of which pressure medium can be drawn from a reservoir to avoid cavitation. According to the invention, the distribution valve and the stop valves are arranged along two parallel axes, while the axes of the two pilot valves are arranged perpendicularly to these two axes. The anti-cavitation valves in turn extend perpendicularly to the axes of the distribution valves, the stop valves and the anti-cavitation valves.

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: Disclosed is a hydraulic control valve having a holding valve with improved response characteristics.

Abstract: An integrated three function valve (ITFV) that combines the functions of a bypass valve (e.g. 183a, 185a, 161a) into a single assembly is disclosed. The ITFV allows continued operation after any two failures.

Abstract: A pressure holding apparatus incorporates a hydraulic pressure system having an engine-driven pressure source, a pressure holding valve, and a torque-transmitting mechanism. The torque-transmitting mechanism is selectively engaged and disengaged by fluid pressure from the engine-driven pressure source during normal powertrain operation. The torque-transmitting mechanism apply chamber is pressurized with the oil by the pressure holding valve when the engine operation is discontinued.

Abstract: In an excavating/slewing work truck, the boom falls freely at the time of lowering operation without requiring any power but the flow rate of a pump increases excessively when the speed is balanced with other acutuators and power loss is inevitable for enhancing the operability. In order to eliminate this inconvenience, a first oil path (41) connecting a bottom side cylinder port (CB) and a tank port (T2), a second oil path (42) connecting a pump port (P2) and a rod side cylinder port (CR), and a third oil path (43) connecting a pump port (P1) and a tank port (T1) are provided, respectively, with first, second and third restrictors (61), (62) and (63) at the boom down position of a change-over valve (51) for the boom cylinder of an excavating/slewing work truck, wherein the first restrictor (61) restricts by such an amount as the work machine lowers gravitationally an the second restrictor (62) restricts by such an amount as the pressure on the boom side is not exceeded.

Abstract: A hydraulic control system (1) has a hydraulic motor (10), which is connected with a control valve (2) via two working lines (8, 9), the control valve (2) being connected with a low-pressure connection (T) and, via a compensation valve (4), with a high-pressure connection (P), to ensure that a return compensation valve (14, 15) is arranged in each working line, each return compensation valve (14, 15) having a nominal flow line (29), which extends unintersectedly in relation to the nominal flow line (28) of the compensation valve (4).

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: 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 fluid system includes first and second control valves that control fluid communication with first and second actuators. The first control valve may combine fluid flow from a second end port of the first actuator with fluid flow from a pressurized fluid source when providing a supply of fluid to a first end port of the first actuator. The first and second control valves include first and second signal ports in fluid communication with the supply of fluid to the first and second actuators. A resolver outputs a resolved signal pressure equal to the greater of a first signal pressure output by the first signal port and a second signal pressure output by the second signal port. A compensator in fluid communication with the first control valve and the first actuator controls fluid flow from the first control valve to the first actuator based on the resolved signal pressure.

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: An actuator is prevented from an abrupt descent by supplying a high-pressure hydraulic fluid drained upon the descent of the actuator to a path on a supply side of the actuator, provided is a main spool mounted in a path between a hydraulic pump and the actuator and controlling the drive of the actuator, a poppet mounted in a path between the main spool and the actuator and preventing the actuator from the descent, a spool mounted between a back-pressure and a feedback path of the poppet and communicating the back-pressure chamber with a path at an outlet of the main spool upon switching, and a fluid flow-reducing path communicating the back-pressure with the feedback path upon the switching of the spool and reducing hydraulic fluid drained from the actuator.