Abstract: Embodiments of the disclosure include a redundant control system for a vehicle. The redundant control system includes first and second actuator pistons mechanically coupled to one another and disposed in respective first and second fluid chambers. The first and second actuator pistons are movable by first and second primary stages. One of the primary stages includes a bypass valve with a pilot valve actuatable in response to movement of the first actuator piston.

Abstract: An electro-hydraulic actuator includes: a motor output rotative power; an external gear pump activated by the motor; a hydraulic actuator operated by a pressurized working fluid supplied by the external gear pump; a manifold block in which a flow channel forming a working fluid circuit of the hydraulic actuator is incorporated; a first portion to store the motor; a second portion to store the external gear pump, the hydraulic actuator, and a reservoir; and a coupling portion to couple the first portion and the second portion in a liquid-tight state. The coupling portion includes a communication hole through which the first portion and the second portion communicate, a rotational shaft of the motor and a driving shaft of the external gear pump are joined to each other, and the external gear pump is attached to the coupling portion while being stored in the manifold block.

Abstract: A quick response steering system with a steering device that steers a vehicle. An electro-hydraulic steering circuit couples to the steering device. The electro-hydraulic steering circuit includes a load sensing pump that pumps hydraulic fluid to a steering cylinder. The load sensing pump increases or decreases output from the load sensing pump in response to a pressure differential between a first fluid line and a second fluid line. A precharge valve diverts hydraulic fluid from the first fluid line to the second fluid line. A controller couples to the steering device and the precharge valve. The controller opens the precharge valve in response to input from the steering device to change a first pressure of the first fluid line to increase an output of the load sensing pump.

Abstract: The present disclosure relates to the technical field of cranes, and in particular to a crane hydraulic control system and a crane. The crane hydraulic control system of the present disclosure includes a prime mover, an execution control mechanism, a hydraulic baking device, a running energy recycling device and an operation energy recycling device. By means of cooperation among the operation energy recycling device, the energy recovery device and the hydraulic energy conversion device, kinetic energy in a driving braking process of the crane and the potential energy in a load lowering process are respectively converted into hydraulic energy for recovery, storage and reuse, therefore, the present disclosure can achieve the recovery of the superstructure energy and the lower vehicle energy of the crane so as to effectively reduce the energy waste.

Abstract: Embodiments of the present disclosure disclose a drive for an electric clutch if a winch. The drive comprises a pusher block having a first end, a second end, and a transmission component arranged on a central portion of the pusher block to drive a transmission shaft; a first driving unit connected to the first end to drive the first end to reciprocate between a first position and a second position; and a second driving unit connected to the second end to drive the second end to reciprocate between a third position and a fourth position. The drive enables switching of the transmission shaft between a high speed mode, a low speed mode, and an idle mode. A winch including the drive is also disclosed.

Abstract: An apparatus for controlling a hydraulic machine, for example a turbine, pump or pump turbine, using variable-speed driven fixed displacement pumps. The apparatus includes a device for carrying out an emergency shut-off that is characterized by low energy consumption and high efficiency while guaranteeing all the operation-relevant and safety-relevant requirements of a hydraulic machine.

Abstract: A working machine includes a lower body, a turning body, a turning manipulating member which turns the turning body, a hydraulic motor which rotationally drives the turning body, a brake device which brakes the hydraulic motor, a main hydraulic source which supplies hydraulic oil to the hydraulic motor, and a direction control valve which controls a flow direction of the hydraulic oil according to the manipulated variable of the turning manipulating member, in which in a state where the hydraulic motor is braked by the brake device based on a manipulation of a brake manipulating member, when the turning manipulation is performed by the turning manipulating member, a brake applied to the hydraulic motor by the brake device is released with respect to turning in an indication direction indicated by the turning manipulation such that the turning body turns in the indication direction.

Abstract: An object of the present invention is, even if an abnormality occurs in an oil pressure circuit of an automatic transmission, to avoid traveling performance deterioration by the abnormality when gear change is performed. The present invention provides a control device of an automatic transmission and a method of controlling the automatic transmission, each of which switches from a normal state to an abnormality diagnosis state at a predetermined change gear ratio to diagnose whether there is an abnormality in an automatic transmission, the normal state being a state where an oil pressure supply portion supplies oil pressure to a predetermined friction engaging element, the abnormality diagnosis state being a state where an abnormality diagnosis oil pressure supply portion including an oil pressure supply passage different from an oil pressure supply passage of the oil pressure supply portion supplies the oil pressure to the predetermined friction engaging element.

Abstract: An integrated drive generator having a variable input speed and constant output frequency, where the integrated drive generator includes a generator disposed about a first centerline. Also included is a hydraulic trimming device disposed about a second centerline. Further included is an epicyclic differential having a ring gear and a sun gear, wherein at least one of the ring gear and the sun gear drives the generator at a constant output frequency, wherein the epicyclic differential is disposed about a third centerline, wherein the third centerline is coaxial with the second centerline.

Abstract: A system controlling pressure in a transmission including a variable displacement pump, a circuit carrying fluid from the pump to the transmission, a valve using fluid in said circuit to regulate pressure that controls displacement of the pump, a source of control pressure including an accumulator, a first spring acting with said source causing the valve to change the regulated pressure, and a second spring acting with feedback pressure from said circuit to oppose said change.

Abstract: A hydraulic valve (3, 3?) of a servo-control for feathering the blades (1) of a rotorcraft rotor. The hydraulic valve (3, 3?) comprises a main valve member (5) and an emergency valve member (6) blocked relative to a valve cylinder (4) of the hydraulic valve (3, 3?) by means of a pin (23) in sliding thrust engagement in a cavity (24) of the emergency valve member (6). Relative movement between the emergency valve member (6) and the valve cylinder (4) initiating sliding movement of the pin (23) inside the cavity (24) and causing mover means (27) for moving the pin (23) to be put into operation, thereby releasing the emergency valve member (6) to move freely.

Abstract: A hydraulic cylinder system 1 is provided with a plurality of cylinders 3a and 3b, valves 4a and 4b provided at each of the cylinders 3a and 3b for adjusting amounts of operating fluid into and out of the cylinders 3a and 3b, driving systems 5a and 5b having motors 6a and 6b provided at each of the valves 4a and 4b for driving the valves 4a and 4b, and a connecting member 8 for connecting the motors 6a and 6b of the driving systems 5a and 5b in a manner capable of interlocking with each other.

Abstract: A hydrostatic positive displacement machine (1) with a variable displacement volume includes a cradle (3) pivoted by a hydraulic positioning device (7) having a positioning piston device (8). A position-controlled control valve (10) generates a control pressure and includes axially displaceable and locked setting valve means (20) and the rotatable feedback valve means (21). Control cross sections are exposed by an axial displacement of the setting valve means (20) relative to the feedback valve means (21) and are closed by rotational movement of the feedback valve means (21) relative to the setting valve means (20).

Abstract: To provide a vehicle electronic control unit including a first microcomputer (2, 3) and a second microcomputer (3, 2) capable of transmitting and receiving signals to and from the first microcomputer. One of the first microcomputer and the second microcomputer outputs a PWM signal to the other microcomputer (3, 2). The other microcomputer detects an on-time of the PWM signal, performs a self diagnosis according to the detected on-time, and outputs a self diagnosis result to the one microcomputer. The one microcomputer diagnoses the other microcomputer based on the self diagnosis result.

Abstract: A hydraulic drive circuit is provided that can achieve high responsiveness, high precision, and high efficiency at a low cost in a hydraulic drive system popularly used in an industrial machine such as a press machine, a construction machine, and the like.

Abstract: A safety system for bypassing counter balance valves of a catwalk hydraulic cylinder from a remote location in a safe and controlled manner. Oil from a base end of the hydraulic cylinder is routed around the counter balance valves and flows through a velocity fuse to a needle valve, a check valve, and a pump outlet.

Abstract: A hydraulic circuit for controlling a component of a hydraulic machine includes an actuator having a head end chamber and a rod end chamber, the actuator having an extended position for moving the component in a first direction and a retracted position for moving the component in a second direction. The hydraulic circuit includes a regeneration valve having an open position for fluidly connecting the head end chamber to the rod end chamber, a first control valve having a first open position, a second open position for fluidly connecting the regeneration valve to the return tank and substantially fluidly disconnecting the rod end chamber from the fluid source, and a closed position, and a second control valve having a first open position, a second open position, and a closed position for substantially fluidly disconnecting the rod end chamber from the fluid source.

Abstract: A hydraulic system for actuating a transmission shifting element that comprises control and shifting valves. A first surface of a valve slide of the control valve is a differential surface between two functional surfaces of the slide that axially bound an area of the slide having a smaller diameter, by which the actuation pressure is adjusted. When the shifting valve is in a second switch position, a total force component acts upon the slide of the control valve which moves the slide such that the actuation pressure is equal to a system pressure. The total force component corresponds at least to the sum of a first force component equivalent to a pressure signal applied to a second surface of the slide of the control valve and a second force component equivalent to an actuation pressure applied to the first surface of the slide of the control valve.

Abstract: The present disclosure relates to fault detection, isolation and reconfiguration schemes, architectures and methods for use in electrohydraulic actuation systems for construction equipment. In one embodiment, a supervisory controller adapted to interface with a main controller of the construction vehicle is provided. A plurality of control nodes that interface with the supervisory controller are also disclosed, each of which includes pressure and position sensors. The nodes also include a first actuator control node for controlling operation of a first hydraulic actuator, a second actuator control node for controlling operation of a second hydraulic actuator, and a pump control node. The control system has an architecture in which faults are detected and isolated at the supervisory controller level and, where possible, within each of the control nodes at a sensor level, a component level, and a subsystem level.

Abstract: The present disclosure relates to fault detection, isolation and reconfiguration schemes, architectures and methods for use in electrohydraulic actuation systems for construction equipment. In one embodiment, a supervisory controller adapted to interface with a main controller of the construction vehicle is provided. A plurality of control nodes that interface with the supervisory controller are also disclosed, each of which includes pressure and position sensors. The nodes also include a first actuator control node for controlling operation of a first hydraulic actuator, a second actuator control node for controlling operation of a second hydraulic actuator, and a pump control node. The control system has an architecture in which faults are detected and isolated at the supervisory controller level and, where possible, within each of the control nodes at a sensor level, a component level, and a subsystem level.

Abstract: An electric motor drives a variable capacity backup hydraulic pump that can supply pressure oil to an actuator when a loss or reduction occurs in the function of an aircraft central hydraulic power source. A power source unit rectifies electric power supplied from a variable frequency supply. A driver supplies the electric power from the power source unit, and drives the electric motor so as to rotate the pump at a predetermined constant rotational speed. The constant rotational speed is set, based on the change in the efficiency of each of the pump, the electric motor, and the driver with respect to the rotational speed of the pump, such that the overall efficiency, obtained as a product of these efficiencies, has a maximum value.

Abstract: A pilot circuitry is disclosed for controlling the activation of an emergency feathering system of a wind turbine by means of a pilot pressure, wherein the pilot circuitry comprises at least two parallel control circuits for providing a pilot pressure. Additionally, a selector may be provided for selectively preventing a control circuit from providing the pilot pressure to the emergency feathering system in case of malfunction of the control circuit.

Abstract: A method of performing a pump check for a brake system comprises determining a first position of a pump with a pump position sensor upon ignition of a vehicle. A pump motor is powered based upon a preselected operating condition. A second position of the pump is determined with the pump position sensor. The first position of the pump and the second position of the pump are compared. The pump motor is confirmed as operational when the second position of the pump is different from the first position of the pump.

Abstract: The invention relates to a drive system for an infeed conveyor (22) of a harvester (10), having an adjustable hydraulic pump (66), the flow rate and flow direction of which can be adjusted by means of a first actuator (76), said hydraulic pump being connected to a hydraulic motor (68) which drives the infeed conveyor (22). A controller (70) is connected to a foreign-body detection device (108) and to a first valve (90) for controlling the actuator (76) that controls the hydraulic pump (66). The controller (70) controls the first valve (90) at least for a short time by reversing the flow direction is a foreign body appears. In addition, it is suggested that the hydraulic motor (68) has an adjustable displacement volume, and that the controller (70) increases the hydraulic motor displacement volume (68) is a foreign body appears.

Abstract: A slewing-type working machine includes: a hydraulic motor for slewing an upper slewing body; a hydraulic pump; a slewing operation device including an operation member; a control valve controlling the hydraulic motor based on an operation signal of the slewing operation device; first and second pipe-lines connecting first and second ports of the hydraulic motor to the control valve; communication switching devices switching communication and cutoff between both pipe-lines and a tank; an electric motor; an electric storage device; and a controller, which communicates an outlet-side pipe-line to the tank during slewing, makes a brake based on a regenerative action by the electric motor and the electric storage device and causes the electric storage device to store regenerative power, upon deceleration operation. Upon failure occurrence, the controller brings the communication switching devices to a communication-cutoff state and stops the regenerative action to secure slewing.

Abstract: One embodiment of the system comprises a towable machine having at least one hydraulic motor arranged on the machine and operable to drive at least one wheel arranged on the machine. At least one hydraulic propelling pump is arranged to supply hydraulic fluid flow via a hydraulic circuit to the hydraulic motor to selectively drive the wheel. The system has a non-operative configuration wherein hydraulic fluid flow is blocked between the hydraulic motor and the hydraulic pump. A pressure sensor is associated with the hydraulic circuit to detect an improper pressure load when the circuit is in a non-operative configuration, and operates to trigger an alarm element.

Abstract: A hydraulic system for aircraft wherein at least one circuit includes two hydraulic pumps, at least one of which is driven by an engine that may suffer uncontained failure that can damage hydraulic lines close to the pump, is equipped with pressure sensors for the hydraulic fluid in the lines close to the pump and a sensor for the hydraulic fluid level in a hydraulic tank of the circuit supplied by the pump. A control system for a cut-out valve installed on a suction line wherein the fluid arrives at the pump includes logic that determines the occurrence of an uncontained engine failure requiring the isolation of the pumps from line elements that may have been damaged from measurements of the fluid pressures in the lines, from measurement of the level of fluid in the tank and from information supplied late by a uncontained engine failure detection system to command the closure of the cut-out valve.

Abstract: Systems and method for shutting down a turbine, with the system including a housing defining first and second flowpaths therein, and an inlet coupled to the housing and fluidly coupled to a source of a fluid and to the first and second flowpaths. The system also includes a first outlet coupled to the housing and selectively coupled to the first and second flowpaths, and a second outlet coupled to the housing and selectively coupled to the first and second flowpaths. The system further includes first, second, and third control valves received in the housing and intersecting the first and second flowpaths. The first, second, and third control valves are each movable between a tripped position and an untripped position, such that if two out of three are in the tripped position, fluid is blocked from the first outlet and is directed to the second outlet.

Abstract: A crash barrier system is provided that generally includes a hydraulic actuator driven piston operably connected to a hydraulic circuit and the crash barrier. In general, the hydraulic circuit includes a normal-UP and normal-DOWN section, an emergency-UP section, and an overpressure relief sub-system. In order to automatically provide corrective action in the event of an overpressure condition, the overpressure relief sub-system includes an external pressure relief valve that is connected to the hydraulic circuit. Upon occurrence of condition that causes the hydraulic fluid pressure to exceed a predetermined value, hydraulic fluid is released through the pressure relief valve to maintain the pressure at or below the predetermined value.

Abstract: A hydraulic control circuit for the overcontrol of a hydraulic system which controls a drive, in particular for controlling a hydraulic motor (5) for driving a slewing gear of a crane superstructure, wherein the pressure lines (3.9, 3.10) for the hydraulic motor (5) are connected by means of a supply piston (3.2) to a hydraulic pump (2) or a tank (1), and the pressure lines (3.9, 3.10) are each assigned pilot valves (3.4, 3.3), shuttle valves (3.8, 3.7) and directional control valves (3.6, 3.5). The shuttle valves (3.7, 3.8) are connected by means of control lines (3.11, 3.12) to an activatable proportional pilot valve (6), such that the separately activatable directional control valves (3.5, 3.6) can thus be activated by means of said pressure, which is built up by the pilot valve (6).

Abstract: There is provided an abnormality determination unit that determines whether or not an output measurement unit is abnormal, in order to determine abnormality of the output measurement unit. When the output measurement unit is abnormal, the operation of an elastic actuator is controlled not in accordance with a measurement result of the output measurement unit but in accordance with an internal state model.

Abstract: Construction equipment having an electric control lever is provided, which can intercept a control signal applied to a flow control valve when trouble occurs in the electric control lever or a control unit.

Abstract: A method of operating a control valve assembly for a hydraulic system includes detecting the current operation of a first position sensor and a second position sensor to determine if at least one of the first position sensor and the second position sensor is inoperable. A pressure of the fluid at a first work port and a second work port is measured, and one of a first valve and a second valve is actuated when one of the first position sensor and the second position sensor is determined to be inoperable. The first valve is actuated based upon the fluid pressure measured at the second work port to adjust the flow of the fluid through the first work port. The second valve is actuated based upon the fluid pressure measured at the first work port to adjust the flow of the fluid through the second work port.

Abstract: A control system for transferring fluid between a fluid supply and a process. The control system includes a transfer controller, which outputs a transfer signal that corresponds to a time varying fluid transfer rate, and plural valves that are plumbed in parallel for connection between the fluid supply and the process. Each valve has a corresponding input to receive an actuation signal that enables a closed state or an open state. The system also includes plural means for limiting the rate of fluid flow corresponding to the plural valves, and a valve drive that is coupled to the corresponding inputs of the plural valves, which operates to generate a sequences of valve actuation signals that result in a combined fluid flow rate through the plural valves selected to track the time varying fluid transfer rate defined by a modulated transfer signal within a margin of error.

Abstract: A fluid circuit includes a tank for holding fluid, a hydraulic device having a predetermined load configuration, and a pump for delivering the fluid under pressure to the hydraulic device. Sensors measure at least one of a supply pressure, a tank pressure, and a position of a portion of the hydraulic device. A controller estimates or reconstructs an output value of any one sensor using the predetermined load configuration in the event of a predetermined failure of that sensor, ensuring continued operation of the hydraulic device. A method for estimating the output value includes sensing output values using the sensors, processing the output values using the controller to determine the presence of a failed sensor, and calculating an estimated output value of the failed sensor using the predetermined load configuration. Operation of the hydraulic device is maintained using the estimated output value until the failed sensor can be repaired.

Abstract: An actuator having two or more interconnected movement components, wherein the movement components are designed as linear actuators with substantially coaxial longitudinal axes or longitudinal axes that are parallel to each other and that are interconnected in longitudinal direction such that their linear movements are superimposed on one another, and such that at least one of the linear actuators can be stopped at one or several predetermined positions.

Abstract: A pressure sensor (17) is provided for detecting the discharge pressure of a hydraulic pump (11). An abnormality detection section (23) of a controller (21) detects a dry operation of the hydraulic pump (11) when the discharge pressure detected by the pressure sensor (17) becomes equal to or lower than a judgment reference pressure determined in advance according to the driving rotation speed of the hydraulic pump (11).

Abstract: A hydraulic system includes at least one hydraulic circuit with at least one pump, one or more consumer equipment units, at least one HP discharge line comprising at least one bypass, the bypass being located between the pump and the units, at least one return line including at least one bypass, the bypass being located between a tank and the units. The hydraulic system further includes at least one closure element on the at least one HP line between the bypass and the units, and at least one nonreturn valve on the at least one return line between the bypass and the units. The closure element is placed automatically in the closed position when a break of the HP line is detected downstream of the closure element of the HP line.

Abstract: A crash barrier system is provided that generally includes a hydraulic actuator driven piston operably connected to a hydraulic circuit and the crash barrier. In general, the hydraulic circuit includes a normal-UP and normal-DOWN section, an emergency-UP section, and an external pressure relief valve. In order to automatically provide corrective action in the event of an overpressure condition, the external pressure relief valve is connected to the hydraulic circuit. Upon occurrence of condition that causes the hydraulic fluid pressure to exceed a predetermined value, hydraulic fluid is released through the pressure relief valve to maintain the pressure at or below the predetermined value.

Abstract: A voting solenoid system and method is configured to selectively apply fluid pressure above and below a threshold value, to a fluid node. The voting solenoid arrangement includes first and second solenoid valve pairs, each pair including first and second solenoid valves. The valve pairs are located in parallel fluid communication with a fluid pressure source, each of the first and second solenoid valves being alternately actuatable between energized and de-energized states. The solenoid arrangement is configured so that a change of state of the first and second valves of either of the valve pairs alternately applies fluid pressure above and below the threshold value, to the fluid node.

Abstract: A crash barrier system is provided that generally includes a hydraulic actuator driven piston operably connected to a hydraulic circuit and the crash barrier. In general, the hydraulic circuit includes a normal-UP and normal-DOWN section, an emergency-UP section, and an overpressure relief sub-system. In order to automatically provide corrective action in the event of an overpressure condition, the overpressure relief sub-system includes an external pressure relief valve that is connected to the hydraulic circuit. Upon occurrence of condition that causes the hydraulic fluid pressure to exceed a predetermined value, hydraulic fluid is released through the pressure relief valve to maintain the pressure at or below the predetermined value.

Abstract: A system, apparatus and method of verifying operation of a vehicle fluid brake system shutoff valve is provided, wherein the shutoff valve is adapted to enable or inhibit the transmission of fluid pressure to at least one brake solenoid valve that controls operation of at least one brake actuator so as to effect wheel braking. In verifying operation of the system, the shutoff valve is commanded to inhibit the transmission of fluid pressure to the at least one brake solenoid valve, and the at least one brake solenoid valve is commanded to apply fluid pressure to the at least one brake actuator. An operational status of the shutoff valve is determined based on the absence or presence of wheel braking.

Abstract: A primary scotch yoke and a secondary scotch yoke are coupled in opposing arrangement and rigidly attached to a linearly reciprocating element. Each scotch yoke includes a rotary actuator with a cam follower and a yoke attached to the reciprocating element. Each yoke has a cam with an open gap through which the follower may be disengaged from the cam and stopped to an idle position. The follower of the secondary scotch yoke is kept idle in a position similarly disengaged from its cam. A controller detects a failure in the primary scotch yoke, disengages the cam follower of the primary yoke from its cam, and energizes the secondary scotch yoke, thereby causing its cam follower to engage its yoke and continue to provide uninterrupted motion to the reciprocating element, in particular the portable pneumatic pump driving an artificial heart.

Abstract: An apparatus for hydraulically adjusting the blades of an impeller of an axial-flow fan, comprising an adjustment cylinder that on both sides of a piston displaceably disposed in the cylinder has a first chamber and a second chamber respectively provided with a connection to control oil lines connected to four-way valves. Not only a feed line leading to one of the control oil lines, but also a return line connected to the other control oil line, is each divided into two parallel branch lines. Two redundant four-way valves are provided, each being disposed in one of the parallel branch lines. Disposed in each branch line of each control oil line, between the respective connection and the respective four-way valve, is a seat valve that closes by spring force.

Abstract: A control arrangement for a valve-controlled hydrostatic displacement contains a control unit for controlling the valve-controlled hydrostatic displacement machine, a sensor electronics portion for detecting sensor data of a power electronics portion and of the valve-controlled hydrostatic displacement machine, and the power electronics portion for furnishing a current necessary for operating the valve-controlled hydrostatic displacement machine. The control unit, the sensor electronics portion, and the power electronics portion are connected, as are the sensor electronics portion, the power electronics portion, and the valve-controlled hydrostatic displacement machine, which in turn are each connected to one another via bidirectional communications lines.

Abstract: A hydraulic system for aircraft wherein at least one circuit includes two hydraulic pumps, at least one of which is driven by an engine that may suffer uncontained failure that can damage hydraulic lines close to the pump, is equipped with pressure sensors for the hydraulic fluid in the lines close to the pump and a sensor for the hydraulic fluid level in a hydraulic tank of the circuit supplied by the pump. A control system for a cut-out valve installed on a suction line wherein the fluid arrives at the pump includes logic that determines the occurrence of an uncontained engine failure requiring the isolation of the pumps from line elements that may have been damaged from measurements of the fluid pressures in the lines, from measurement of the level of fluid in the tank and from information supplied late by a uncontained engine failure detection system to command the closure of the cut-out valve.

Abstract: A hydraulic actuator is configured to provide redundant boost control to an aircraft within approximately the same space required by a single hydraulic cylinder. The hydraulic actuator includes a housing and a piston assembly disposed within the housing. The piston assembly includes a ram, a first piston secured to the ram, and second and third pistons disposed on the ram such that the second and third pistons are translatable relative to the longitudinal axis of the ram. The pistons form two hydraulically separate actuator cylinders within the space required by a single cylinder which results in a reduction in the weight and size of the hydraulic actuator.

Abstract: A control device includes an arm cylinder having a cylinder body and a piston that slides inside the cylinder body and a pump that supplies working oil to the arm cylinder, and decelerates the piston when it approaches a stroke end of the arm cylinder by adjusting a supply rate of the working oil supplied from the pump to the arm cylinder and a discharge rate of the working oil discharged from the arm cylinder. The position at which the piston starts decelerating is set further from the stroke end as the moving speed of the piston becomes higher.

Abstract: A valve assembly (2) forming a bridge circuit and a hydraulic actuator comprising at least one valve assembly (2) are disclosed. The valve assembly (2) is fluidly connectable between a fluid source (3) and a fluid drain (4). The valve assembly (2) comprises a first valve (8) fluidly connected between the fluid source (3) and a first diagonal point (12) of the bridge circuit, a second valve (9) fluidly connected between the fluid source (3) and a second diagonal point (13) of the bridge circuit, a third valve (10) fluidly connected between the first diagonal point (12) and the fluid drain (4), and a fourth valve (11) fluidly connected between the second diagonal point (13) and the fluid drain (4). The valves (8, 9, 10, 11) are such that in the case of a power cut off, flows of fluid away from the diagonal points (12, 13) are prevented.

Abstract: A fluid circuit includes a tank for holding fluid, a hydraulic device having a predetermined load configuration, and a pump for delivering the fluid under pressure to the hydraulic device. Sensors measure at least one of a supply pressure, a tank pressure, and a position of a portion of the hydraulic device. A controller estimates or reconstructs an output value of any one sensor using the predetermined load configuration in the event of a predetermined failure of that sensor, ensuring continued operation of the hydraulic device. A method for estimating the output value includes sensing output values using the sensors, processing the output values using the controller to determine the presence of a failed sensor, and calculating an estimated output value of the failed sensor using the predetermined load configuration. Operation of the hydraulic device is maintained using the estimated output value until the failed sensor can be repaired.