Abstract: A lock valve switching section switches a lock valve from a locked state to a released state when a lock member is switched from a locked position to a release position. An erroneous operation monitoring section maintains the lock valve in the released state when the pilot pressure is equal to or more than a predetermined pressure when elapsed time, which is from a point in time where the lock member is switched from the locked position to the release position, is equal to or more than the predetermined time. The erroneous operation monitoring section switches the lock valve to the locked state when the pilot pressure is equal to or more than the predetermined pressure when the elapsed time is less than the predetermined time.

Abstract: First and second mechanical hydraulic valves are disposed between a pump and the cap side chamber of an actuator and the pump and the rod chamber of the pump. The first and second valves are actuated as a result of respective pressure differentials applied across the valves. A controller controls flow from a pump in response to a commanded motion to control movement of the actuator, and cause the valves to open. The valves are disposed in their no-flow positions when the pump is not operative, and when the hydraulic system of off or locked out to hold a load.

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: A hydraulic control device includes: a recovery oil passage; a regenerative motor that rotates an output shaft of an engine in response to a supply of the hydraulic fluid and is driven to rotate by rotation of the output shaft of the engine; a regenerative oil passage for guiding return oil from a boom cylinder to the regenerative motor without passing the return oil through the recovery oil passage; a coupling oil passage that couples the recovery oil passage and the regenerative oil passage to each other; and a regeneration-side check valve that is provided on the coupling oil passage, and allows the hydraulic fluid to flow from the recovery oil passage toward the regenerative motor, and moreover restricts the hydraulic fluid from flowing from the regenerative motor toward the recovery oil passage.

Abstract: A hydraulic transmission unit comprises at least one pressure regulation valve (1) and a pilot control valve (2) which is connected to the pressure regulation valve (1) by a pilot control line (35). A pre-filling valve (3, 303) sets a pre-filling pressure (p—3) to avoid draining of a clutch (20) and the lines (231, 331) connected to the clutch (20) in an operating condition in which the clutch (20) is not actuated. To avoid draining when the clutch when in the operating condition, the pilot control line (35) is also connected to at least one line (236, 238, 336, 338) which is pressurized with a second pre-filling pressure (p—3).

Abstract: A brake valve is insertable into a working line of a hydrostatic travel drive. The brake valve has a main stage with a first port connected to a variable displacement pump of the drive system and a second port connected to a motor of the drive system. The main stage has a slide piston positionable in a valve bore. In a freewheeling position, a connection is maximally open with minimal throttling between the two ports. In pressure-reducing positions, a regulable, throttled connection is open from the second to the first port to brake the motor. In pressure-limiting positions, a regulable, throttled connection is open from the first to the second port to begin to throttle a pressure medium flow from the variable displacement pump to a pressure protection mechanism. The positions lie on a center line of the main stage along which the slide piston is movable.

Abstract: A hydraulic control apparatus is disclosed that controls a hydraulic pump in a construction machine in which a hydraulic actuator is connected to the hydraulic pump via a directional control valve of a closed center type, and in which a position of the directional control valve is changed according to an operation amount of an operation member. The hydraulic control apparatus includes a virtual negative control pressure calculating part configured to calculate, based on the operation amount of the operation member and a discharge pressure of the hydraulic pump, a virtual negative control pressure when a negative control system is assumed; and a part configured to calculate a control command value for the hydraulic pump based on the virtual negative control pressure.

Abstract: A composite valve is used in a hydraulic circuit. The composite valve is interposed between a stack valve and a hydraulic power supplier and between the stack valve and a multifunction valve coupled to a hydraulic device. The composite valve includes: stop valves opening/closing communication between the hydraulic power supplier and the stack valve and stop valves opening/closing communication between the stack valve and the multifunction valve; and bypass circuits respectively including stop valves opening/closing communication between the hydraulic power supplier and the multifunction valve, the bypass circuits provided closer to the hydraulic power supplier than the stop valves. This structure makes it possible to simultaneously perform various functions: repair, checking, and/or maintenance on the stack valve; flushing; and repair, checking, maintenance, and/or a trial run of the hydraulic device. The composite valve has uniform circuit configurations, which facilitates production of the valve.

Abstract: A hydraulic control system for a machine is disclosed. The hydraulic control system may have a tank, a pump, a swing motor having a first chamber and a second chamber, and at least one control valve configured to control fluid flow between the pump, the swing motor, and the tank. The hydraulic system may also have an accumulator configured to selectively receive pressurized fluid discharged from the swing motor and selectively supply pressurized fluid to the swing motor and a controller. The hydraulic control system may further include a first valve and a second valve coupled between the accumulator and the first and the second chambers of the swing motor. One of the first or second valve moves between a first position, a second position, and a third position for selective charging and discharging of the accumulator. The second valve also moves between multiple positions to realize selective charging and discharging of the accumulator.

Abstract: There is provided a device and method for high speed hydraulic actuation. The method includes adjusting a position of an actuator using a hydraulic pressure regulator. Adjusting the position of the actuator includes increasing pressure on the hydraulic pressure regulator to open the actuator using a first solenoid, or decreasing pressure on the hydraulic pressure regulator to close the actuator using a second solenoid.

Abstract: The present invention relates to a hydraulic control system for construction machinery capable of variably adjusting a set pressure of a relief valve, which controls a set pressure of a hydraulic system, according to a value inputted by means of pressure in the hydraulic system or the manipulation of a joystick.

Abstract: A system and method for controlling fluid flow through a hydraulic valve in a work machine is disclosed. The system and method may include receiving an input command by a controller configured to control a fluid flow to an actuator, the input command generated by an input controller. The system and method may also include receiving a parameter indicative of pump flow by the controller, determining a first valve command corresponding to the input command and determining a second valve command based upon the parameter that achieves the fluid flow to the actuator corresponding to the first valve command.

Abstract: An independent metering valve (IMV) assembly is disclosed that includes a metering stem including an inlet. The IMV assembly also includes a hydro-mechanical control valve in communication with a fluid source and the inlet. The control valve also including a spool with a closed end and an open end. The control valve includes a biasing member that biases the control valve or spool towards an open position thereby establishing communication between the fluid source and the inlet. The control valve also including a load signal line providing communication between an outlet of the control valve upstream of the inlet and the closed end of the spool. Wherein high pressure in the load signal line allowing the control valve to move towards a closed position thereby overcoming bias of the biasing member and reducing flow to the inlet during a high pressure condition.

Abstract: Embodiments for a turbine-generator position in a compressor bypass flow path are presented. In one example, a method for an engine having a compressor comprises generating energy via a turbine-generator positioned in a bypass flow path of the compressor. In this way, the energy of the recirculated intake air may be recovered by the turbine-generator.

Abstract: Disclosed is an actuator damping control system for reducing shocks imparted to a hydraulic actuator caused by a change in load resulting from an abrupt manipulation of a boom or other working device.

Abstract: A pump displacement control cylinder is configured to control the displacement of a hydraulic pump according to pressure of hydraulic fluid and switches the discharge direction of the hydraulic fluid from the hydraulic pump according to the supply direction of the hydraulic fluid to the pump displacement control cylinder. A forward and backward progression switching valve is configured to switch the supply direction of the hydraulic fluid to the pump displacement control cylinder. A pressure control valve is configured to control the pressure of the hydraulic fluid supplied to the pump displacement control cylinder according to a command value input to the pressure control valve. A control section is configured to execute pump shuttle control which reduces the command value to the pressure control valve when switching between forward and backward progression using a forward and backward progression operation member.

Abstract: Provided is a hydraulic drive apparatus for working machine capable of preventing an excessive pressure reduction on a meter-in side and moving a load in a lowering direction at a stable speed requiring no counter balance valve. The apparatus includes a hydraulic pump, a hydraulic actuator for lowering the load, an operating device, a hydraulic circuit including a meter-in flow passage, a meter-out flow passage and a regeneration flow passage, a control valve, a meter-in-flow-rate controller for controlling a meter-in flow rate, a meter-out-flow-rate controller for controlling a meter-out flow rate to one not lower than the meter-in flow rate, a back pressure generator located downstream of the regeneration flow passage in the meter-out flow passage, and a meter-out-flow-rate limiter. The meter-out-flow-rate limiter minimizes a flow passage area of the meter-out orifice when a pressure in the meter-in flow passage falls to or below a permissible pressure.

Abstract: A hydraulic driving system includes a hydraulic pump, a driving source, a hydraulic cylinder, a closed circuit hydraulic path between the pump and cylinder, a pump-flow-rate control unit controlling a discharge flow rate of the pump, a flow rate control valve between the pump and the cylinder in the fluid path, a directional control unit, a target flow rate setting unit and a control device. The directional control unit allows a flow of fluid from the pump to the cylinder and prohibits a flow of fluid from the cylinder to the pump when fluid is supplied from the pump to the cylinder via the flow rate control valve. The control device controls fluid flow to the cylinder with the flow rate control valve when the target flow rate is within a prescribed range, and with the pump-flow-rate control unit when the target flow rate is greater than the prescribed range.

Abstract: An improvement to the component based hydraulic systems is an integrated electro-hydraulic actuator (EHA) that contains all components necessary to achieve power up, gravity return actuation of a lift mechanism such as the forks of a pallet truck. Further, improvements to known power-up, gravity-down component-based hydraulic circuits are described herein. The improvements provide for power up, gravity return functionality with fewer components as compared known systems. Finally, a method for controlling the EHA and/or hydraulic circuits described above is detailed herein and provides a user with maximum control of a lift mechanism during lower or “down mode,” but also provides for the least amount of energy consumption by the actuator.

Abstract: A construction machine including: a swivel motor; a working attachment having a boom, a boom cylinder, an arm and an arm cylinder; a hydraulic actuator circuit having a first circuit including the boom cylinder and a boom control valve, a second circuit including the arm cylinder and an arm control valve, and a third circuit including the swivel motor and a swivel control valve; first to third pumps for the first to third circuits; a merge valve having a first position for merge of third pump fluid into the first circuit and connection of an unload line of the third circuit to a tank, and a second position for prohibiting the merge; and a merge selecting control section which holds the merge valve at the first position either of when only a swivel operation is performed and when a boom raising operation is performed.

Abstract: A negative control type hydraulic system in which the use of a pilot pump and a load pressure generator between a hydraulic pump and a control valve is not required to prevent a power loss.

Abstract: An energy recovery system for a machine is disclosed. The energy recovery system may have a tank, a pump configured to draw fluid from the tank and pressurize the fluid, an actuator, and an actuator control valve movable to direct pressurized fluid from the pump to the actuator and from the actuator to the tank to move the actuator. The energy recovery system may also have a motor connected to selectively receive fluid discharged from the actuator and mechanically connected to the pump, and an accumulator configured to store fluid discharged from the motor and to direct stored fluid to the motor to drive the pump.

Abstract: In a electropneumatic field device, an electrical field input and a pneumatic supply input are provided. At least one field output is provided at which a field output signal is output based on a field control signal received via the electrical field input. A group comprising at least two modular components of different functionality is provided and at least one modular slot for occupation with either of said modular components from said group. The at least two modular components of the group and the at least one slot are modularly adapted to one another such that interfaces of the slot and interfaces of either of said modular components in the seat merge into one another when the slot is occupied with either of said modular components so that the modular component which is in the slot is connected to the electrical field input and to the at least one field output.

Abstract: The hybrid excavator includes: a first detection sensor for detecting an RCV-manipulated quantity; a second detection sensor for detecting the rotational speed of an electric motor; a hydraulic pump-motor connected to the electric motor; a hydraulic cylinder connected to the hydraulic pump-motor; first and second hydraulic valves installed in first and second passages, respectively, between the hydraulic pump-motor and the hydraulic cylinder; a third hydraulic valve for compensating for or bypassing a flow rate and a controller for receiving an RCV-manipulation signal from the first detection sensor and the rotational speed of the electric motor from the second detection sensor to compare the received values to data of previously stored working conditions, to output a control signal for switching the first and second hydraulic valves, and to block a working fluid from returning into the hydraulic cylinder, so as to thereby quickly stop the working device.

Abstract: A hydraulic drive device for a hydraulic excavator, includes: a first hydraulic pump; a first boom directional control valve and a second arm directional control valve which are connected in parallel to the first pump; a second hydraulic pump; and a second boom directional control valve and a first arm directional control valve which are connected in parallel to the second pump; wherein: the hydraulic drive device also includes: a third hydraulic pump; a third boom directional control valve connected to the third pump and controlling the flow of pressure oil supplied to a boom cylinder; and a third arm directional control valve connected in tandem with the third boom directional control valve and controlling the flow of pressure oil supplied to an arm cylinder.

Abstract: A power regeneration device for an operating machine has a hydraulic cylinder and a return line through which fluid returning to a tank flows when the hydraulic cylinder contracts. The return line branches into a plurality of hydraulic lines through a branching part and includes a regeneration line that which leads returning fluid to the tank via a hydraulic motor to which a generator is connected. A control valve line is connected to the branching part and leads the returning fluid to the tank via a control valve. An electricity storage device stores electric power generated by the generator, and an electric amount detector detects the electric amount of the electricity storage device. A flow rate calculator calculates the flow rate of the returning fluid flowing through the regeneration line and the flow rate of the returning fluid flowing through the control valve line depending on an electric amount signal.

Abstract: A hydraulic circuit for construction equipment is provided, which supplements hydraulic fluid of a hydraulic pump for a cooling fan and hydraulic fluid of a main hydraulic pump and uses the supplemented hydraulic fluid as a hydraulic source of a RCV in order to supply signal pressure to a control valve that controls the driving of a hydraulic actuator.

Abstract: An object of the present invention is to reduce current consumption for switching and holding an actuation position of an electromagnetic change-over valve included in a vehicle height adjusting device for a motorcycle and to surely hold the actuation position. In a rear-wheel side vehicle height adjusting device for a motorcycle, after applying a startup current to a solenoid of a change-over valve in order switch an actuation position of the change-over valve, while switching an applied current to the solenoid to a holding current which is smaller than the startup current and holding the actuation position of the change-over valve, a control section intermittently applies a large current, which is larger than the holding current, to the solenoid.

Abstract: A hydraulic manifold assembly for hydraulic equipment is provided. The hydraulic manifold assembly includes a hydraulic manifold. The hydraulic manifold includes at least four control valves substantially disposed within the hydraulic manifold, at least three check valves substantially disposed within the hydraulic manifold, at least one control module, at least one control valve fluid line, and at least one check valve line. The hydraulic manifold assembly also includes at least one hydraulic cylinder, a hydraulic tank, and at least one hydraulic pump fluidly connected to the hydraulic manifold, and also fluidly connected to the hydraulic tank.

Abstract: A hydraulic control system is disclosed. The hydraulic control system may have an input device to generate a first signal indicative of a desired swing motor movement, and a control valve configured to selectively pass fluid to the swing motor and drain from the swing motor to drive the swing motor based on the first signal. The hydraulic control system may also have a pressure sensor to generate a second signal indicative of a swing motor pressure, a speed sensor configured to a third signal indicative of a swing motor speed, and a controller configured to make a comparison of at least one of the swing motor speed and the swing motor pressure with a threshold speed and a threshold pressure, and open the control valve to drain fluid from the swing motor to the tank based on the comparison when the input device is in a neutral condition.

Abstract: A hydraulic control system for a machine is disclosed. The hydraulic control system may have a tank, a pump, and a fluid actuator. The hydraulic control system may further have an accumulator configured to selectively receive pressurized fluid discharged from the fluid actuator and selectively supply pressurized fluid to the fluid actuator. The hydraulic control system may also have a pressure sensor configured to generate a signal indicative of a pressure of the accumulator, a charge valve, a discharge valve, and a controller in communication with the control valve, the charge valve, and the discharge valve. The controller may be configured to detect stall of the fluid actuator, to make a comparison of the pressure of the accumulator with a threshold pressure, and to selectively move the charge valve to charge the accumulator or move the discharge valve to discharge the accumulator during the stall based on the comparison.

Abstract: An electro-hydraulic control system manages speed of a hydraulic fan by using a solenoid to bias a three position pool of a control valve coupled to a hydraulic pump driving the fan. In a first position, the spool releases pressure on a de-stroke actuator of the pump and allows an on-stroke actuator to increase output pressure corresponding to a speed of an engine driving the pump. In a second position, the spool isolates the de-stroke actuator and fixes the pressure output of the pump. In a third position, the spool couples the de-stroke actuator to the pump output and causes a reduction in the pressure output of the pump. The solenoid coupled to the spool sets the output pressure at which the spool is in the second position.

Abstract: A hydraulic valve device includes a first and a second engine port to a double acting hydraulic motor, a pump, a hand valve which has two open positions, wherein in the first open position the pump is fluidly connected to the first engine port and the tank is fluidly connected to the second engine port; and wherein in the second open position the pump is fluidly connected to the second engine port and the tank is fluidly connected to the first engine port, with a first nonreturn valve, arranged between the pump and second engine port. A piston which by way of the load pressure in the first engine port via a line governs the first nonreturn valve, and a second nonreturn valve arranged, as long as the hand valve is in its first open position, to connect the first engine port to the second engine port.

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

Abstract: A hydraulic circuit is provided. The hydraulic circuit includes a primary pump, a displacement actuator, a charge pump, a direction control valve, and a pressure control valve. The displacement actuator is associated with the primary pump. The charge pump is configured to generate a flow of a pilot fluid. The direction control valve is configured to control the flow of the pilot fluid to the displacement actuator to affect a movement direction of the displacement actuator. The pressure control valve is configured to control a pressure of the pilot fluid to affect a movement amount of the displacement actuator. Further, the hydraulic circuit includes a controller. The controller is configured to control the direction and the pressure control valves to adjust a displacement of the primary pump based at least on one of a sensed engine parameter or a mode of operation of the primary pump.

Abstract: The axial lengths of coupling portions of a flywheel, a rotor shaft, and a pump shaft are reduced to reduce the axial length of an entire power unit. A crankshaft and a flywheel are directly coupled to each other and the flywheel and a rotor shaft are directly coupled to each other. A coupling is directly coupled to an end face of the rotor shaft on the opposite side to the flywheel. A pump shaft is connected to the coupling. Coupling surfaces of the flywheel and the rotor shaft and coupling surfaces the rotor shaft and the coupling are arranged within a width range of a coil.

Abstract: A hydraulic system is disclosed having at least two hydraulic circuits. The disclosed system apportions flow between the two hydraulic circuits based on an assumed flow rate that is held constant in both power-limited and non-power-limited conditions.

Abstract: An oil supply device for a vehicle includes an oil pump driven by a rotation of an internal combustion engine, a hydraulic actuator to which oil is supplied from the oil pump, an engine lubricating system to which the oil is supplied from the oil pump, an oil supply adjusting valve adjusting a supply condition of the oil from the oil pump to the hydraulic actuator and the engine lubricating system, a first oil supply passage supplying the oil from the oil pump to the hydraulic actuator, and a second oil supply passage supplying the oil from the oil pump to the engine lubricating system, wherein the oil supply adjusting valve consistently distributes the oil to the first oil supply passage and the second oil supply passage.

Abstract: A hydraulic system for an access arrangement having a platform configured for movement between a deployed position and a stowed position, the hydraulic system including: at least one hydraulic power unit configured to urge hydraulic fluid through a hydraulic circuit; at least one hydraulic cylinder directly or indirectly connected to a portion of the platform and configured to urge the platform towards at least one of the stowed position and the deployed position, wherein the at least one hydraulic cylinder is in fluid communication with the hydraulic power unit; and a pressure regulating valve in a path between the at least one hydraulic power unit and the at least one hydraulic cylinder, wherein the pressure regulating valve is operable to prevent the at least one hydraulic cylinder from urging the platform to the stowed position if a load on the platform exceeds a specified threshold.

Abstract: A power machine and a power conversion system for a power machine are disclosed. In an exemplary embodiment, the power conversion system includes a pump configured to provide a source of pressurized hydraulic fluid and a control valve assembly to receive the hydraulic fluid. The control valve assembly includes a first valve element configured to direct hydraulic fluid to an actuator when the first valve element is in first and second actuated positions. The control valve assembly also includes a second valve element downstream of the first spool. The first valve element is moveable between an unactuated position and the first and second actuated positions and is configured to direct hydraulic fluid received from the actuator through the second actuated position to the second valve element and to direct hydraulic fluid received from the actuator through the first actuated position to bypass the second valve element.

Abstract: A hydraulic system is disclosed that includes a hydraulic actuator having a head end, a rod end and a piston disposed therebetween. The system also includes a pump configured to supply fluid to both ends of the actuator. The system also includes an energy conservation system that is configured to reduce flow from the pump to the head end of the actuator and to increase flow from a make-up fluid circuit to the head end of the actuator during an overrunning load condition. The energy conservation system also increases flow from the pump to the head end of the actuator and decreases flow from the make-up circuit to the head end of the actuator after the overrunning load condition has ceased.

Abstract: Provided is a hydraulic system for a work machine, which can ensure low temperature responsiveness of remote control valves that perform pilot operations of pilot operated directional control valves for controlling hydraulic actuators, respectively. In order to, with bringing an unloading valve V13 to an unloading position 29, circulate oil to a pilot pump oil passage w that supplies the pressure oil from the discharging circuit Y for a pilot pump 19 to remote control valves PV1, PV2, and PV6, a warm-up circuit H that flows the oil from the discharging circuit Y for the pilot pump 19 to a terminal of the pilot pump oil passage w is provided.

Abstract: A pressurised fluid supply system for an agricultural vehicle (100) includes a main supply circuit (MC) including a variable displacement pump (RP) providing a first source of pressurised fluid to a steering system (SS) of the vehicle and to consumers (WH) connected with the vehicle. A steering supply circuit (SC) includes a fixed displacement pump (LHP) supplying pressurised fluid to the steering system (SS). A pilot pressure circuit (PPC), connectable to supply a second source of pressurised fluid to consumers connected with the vehicle, receives pressurised fluid from the main supply circuit (MC).

Abstract: The present disclosure relates to a hybrid excavator boom actuating system and to a method for controlling the same. The boom actuating system comprises: an electric motor serving as a motor or a generator; an ultra capacitor for storing electricity generated by the electric motor; a hydraulic pump motor driven by the electric motor to supply hydraulic fluid to a boom; a boom control valve which has a closed circuit for selectively connecting or disconnecting an outlet line and an inlet line of the hydraulic pump motor to or from a head or a rod side of the boom; a main pump driven by the engine to supply hydraulic fluid to a bucket, a travel motor or an arm; a motor bypass valve connected to the outlet line and the inlet line to interconnect the outlet line and the inlet line or disconnect the outlet line from the inlet line; and a controller for controlling the electric motor, the hydraulic pump motor, the boom control valve and the motor bypass valve.

Abstract: A method and apparatus for controlling a hydraulic power system that includes a hydraulic motor and a hydraulic pump configured to supply hydraulic fluid to the hydraulic motor is provided. A relief valve is provided that is configured to release hydraulic fluid from a location between the hydraulic pump and the hydraulic motor when a pressure of the hydraulic fluid exceeds a predetermined pressure. A controller is in communication with the hydraulic motor and the hydraulic pump. The controller is configured to determine a first hydraulic fluid flow across the relief valve and determine a desired maximum flow across the relief valve. The controller also can regulate one or both of the hydraulic pump and the hydraulic motor to control the first hydraulic fluid flow based on the desired maximum flow.

Abstract: An energy-recovery generation system for a handling and carrying electric vehicle, comprising a hoisting cylinder (9), wherein an output pipeline of the hoisting cylinder (9) is provided with a pressure sensor unit (1) and a directional valve (2); the directional valve (2) is under the control of the pressure sensor unit (1); a first outlet of the directional valve (2) is connected to a tank (5) through a way of a multi-way valve (4) with an operating handle; the pressure oil, flowing out from a second outlet of the directional valve (2), passes through a pump (7) having an oil suction port capable of bearing pressure or a motor, and then passes through the multi-way valve (4), to finally flow back to the tank (5); the pump (7) having an oil suction port capable of bearing pressure or the motor drives an electric motor (16) to output electric energy; an electric energy output end of the electric motor (16) is connected to an energy storage device (20) through a converter (21).

Abstract: A steering system can include a steering control valve, primary and secondary sources of pressurized fluid, and a controller. The primary and secondary sources of pressurized fluid can be fluidly connected to the steering control valve. The primary source of pressurized fluid can be configured to sense a load pressure requirement from the steering control valve. The controller can be communicably coupled to the primary and secondary sources of pressurized fluid. The controller can monitor a margin pressure of the primary source of pressurized fluid. The controller can determine an operational status of the primary source of pressurized fluid based on the monitored margin pressure.

Abstract: A hydraulic system includes one or more hydraulic pumps, one or more hydraulic motors, a hydraulic tank, and fluid lines. The hydraulic system also includes one or more check valves fluidly connected to the hydraulic pumps and the hydraulic motors. The hydraulic system also includes one or more pilot-operated valves, operably coupled to the check valves by one or more pilot lines. The pilot-operated valves are configured to receive fluid pressure from the fluid lines, opening to allow hydraulic fluid to travel between fluid lines.

Abstract: A relief pressure control system is provided with a controller for outputting, responsive to an adjustment signal output from a dial switch, a control signal to control a relief pressure of a variable solenoid relief valve, a display unit for displaying, responsive to display signals outputted from the controller, a relationship between a circuit pressure output from a pressure sensor and a pressure required by a hydraulic cylinder, and a control device constituting a start instruction unit for instructing a start of control of the variable solenoid relief valve. Stop valves are arranged in sections of main lines, which communicate a directional control valve and the hydraulic cylinder with each other, to open or close the section. The sections are located between positions on the main lines, where the variable solenoid relief valves are connected to the main lines, respectively, and the hydraulic cylinder.

Abstract: A hydraulic control system in a continuously variable transmission (2) is provided with a pump (40) for supplying hydraulic fluid, a main line (41), a line pressure valve (V3), an auxiliary line (42) and a auxiliary pressure valve (V9). The line pressure valve (V3) being arranged to control a line pressure LP in the main line (41) by discharging a surplus of hydraulic fluid supplied by the pump (40) into the auxiliary line (42). The auxiliary pressure valve (V9) is arranged to variably control auxiliary pressure AP in the auxiliary line (41), preferably in dependence on the line pressure LP in the main line (41).