Abstract: A hydraulic valve assembly includes a connection section, a first valve section and a pressure line. The first valve section has a first spool piston, a first spool diverter, at least one first consumer port and at least one second consumer port. The first spool diverter can be switched at least into a first spool diverter switching position and a second spool diverter switching position. A shut-off valve is disposed in the pressure line and blocks the pressure line in a blocking position and can be switched from the blocking position into a first release switching position and a second release switching position. The shut-off valve switches into the first release switching position when the first spool diverter is in the first spool diverter switching position and into the second release switching position when the first spool diverter is in the second spool diverter switching position.

Abstract: A refuse vehicle includes a chassis and a vehicle body. A variable displacement pump is positioned within the vehicle body and is configured to pump hydraulic fluid from a hydraulic fluid reservoir into a high pressure line of a hydraulic circuit. A lifting system on the vehicle includes at least one actuator in fluid communication with the variable displacement pump, which delivers pressurized hydraulic fluid from the hydraulic fluid reservoir to the actuator through the high pressure line to adjust a position of the actuator. A valve is positioned downstream of the variable displacement pump. In a first valve position, the valve restricts flow outward from the high pressure line. In a second valve position, the valve directs fluid from the high pressure line into a lower pressure line to reduce a hydraulic pressure within the high pressure line and adjust an output parameter of the variable displacement pump.

Abstract: A working machine includes a first traveling fluid passage connected to a first pressure-receiving portion, a second traveling fluid passage connected to a second pressure-receiving portion, a third traveling fluid passage connected to a third pressure-receiving portion, a fourth traveling fluid passage fluidly connected to a fourth pressure-receiving portion, and a connection fluid passage connecting at least two of the first, second, third and fourth pressure-receiving portions to each other. When a traveling operation member is operated, operation fluid flows to the first pressure receiving portion through the first traveling fluid passage, to the second pressure receiving portion through the second traveling fluid passage, to the third pressure receiving portion through the third traveling fluid passage, and to the fourth pressure receiving portion through the fourth traveling fluid passage.

Abstract: A redundant steering system comprises a primary power source; a secondary power source; first and second pumps operatively coupled to the primary and secondary power sources, respectively, to output first and second supplies of hydraulic fluid to a steering cylinder based on operation of the primary and secondary power source, respectively; first and second pairs of selector valves respectively coupled to the first and second pumps; and a charge circuit coupled to respective control inputs of the first and second pairs of selector valves to selectively supply hydraulic fluid to the control inputs of the first and second pairs of selector valves to stop hydraulic fluid from only one of the first pump and the second pump from being provided to the steering cylinder and to provide hydraulic fluid to the steering cylinder from only one of the other of the first pump and the second pump.

Abstract: A control system for an aircraft includes a hydraulic pump, first hydraulic line, second hydraulic line, a first actuator coupled with a first control surface, a second actuator coupled with a second control surface, and a third actuator coupled with a third control surface. The first control surface and the second control surface are at a distance to each other and symmetrically relative to a symmetry axis. The third control surface is substantially on the symmetry axis, and the first hydraulic line and the second hydraulic line are connected to the hydraulic pump. The first actuator is connected to the first hydraulic line, and the second actuator is connected to the second hydraulic line. The third actuator is connected to the first hydraulic line downstream of the first actuator at a junction point, and the first hydraulic line at least partially includes a larger diameter than the second hydraulic line.

Abstract: To improve operability and work efficiency while achieving reduction of the number of parts and simplification of circuit structure, in a hydraulic control system equipped with hydraulic actuators whose hydraulic power sources are both the first, second hydraulic pumps.

Abstract: A refuse vehicle includes a chassis and a vehicle body. A variable displacement pump is positioned within the vehicle body and is configured to pump hydraulic fluid from a hydraulic fluid reservoir into a high pressure line of a hydraulic circuit. A lifting system on the vehicle includes at least one actuator in fluid communication with the variable displacement pump, which delivers pressurized hydraulic fluid from the hydraulic fluid reservoir to the actuator through the high pressure line to adjust a position of the actuator. A valve is positioned downstream of the variable displacement pump. In a first valve position, the valve restricts flow outward from the high pressure line. In a second valve position, the valve directs fluid from the high pressure line into a lower pressure line to reduce a hydraulic pressure within the high pressure line and adjust an output parameter of the variable displacement pump.

Abstract: Systems and methods corresponding with improved wellfield management are provided. In some examples, the system may initiate a step drawdown test of well efficiency to determine a cause of a decreased discharge rate of the wellfield site. The system may alter pumping of the wellfield site based on the step drawdown test, wherein a command signal is transmitted via a SCADA system to the wellfield site.

Abstract: An electrically powered hydraulic system for a working machine includes: an electric motor to power a working hydraulic pump. A flow of hydraulic fluid generated by the hydraulic pump is controlled by the operation rotational speed of the electric motor. An electronic control unit is configured to: when an operator input device is in a first operating range, maintain the electric motor at a constant rotational speed, and control a variation in flow of hydraulic fluid to the hydraulic function with an electronically controlled control valve, and when the operator input device is in a second operating range, control a variation in flow of hydraulic fluid by varying the electric motor rotational speed and by controlling the control valve, according to displacement of the operator input device.

Abstract: A hydraulic system for a work vehicle includes a first pump providing a first flow in a first circuit having a first pressure. A first load sense circuit connected to a first load sensing compensator of the first pump. The first load sense circuit having a first load sense pressure. A supplemental pump provides a supplemental flow to a supplemental circuit having a supplemental pressure. A supplemental load sense circuit connected to a supplemental load sensing compensator of the supplemental pump. A first supplemental valve selectively enables flow from the first load sense circuit to the supplemental load circuit based in part on a first pressure differential between the first pressure and the first load sense pressure. A first valve selectively enables flow from the supplemental circuit to the first circuit when the supplemental pressure is equal to or greater than the first pressure.

Abstract: A hydraulic system for a work vehicle includes a first pump providing a first flow to a first circuit. A first pressure sensor measures a first pressure in the first circuit. A first swashplate angle sensor measures a first angle of a first swashplate of the first pump. A supplemental pump provides a supplemental flow to a supplemental circuit. A supplemental pressure sensor measures a supplemental pressure in the supplemental circuit. A supplemental valve adjusts the load sense signal provided to a supplemental load sensing compensator of the supplemental pump. A first valve selectively enables flow from the supplemental circuit to the first circuit when the supplemental pressure is equal to or greater than the first pressure. A controller determines to operate the supplemental pump in one of a standby condition and a use condition based in part on the first angle of the first swashplate.

Abstract: An example valve includes a first port fluidly coupled to a source of fluid, a second port fluidly coupled to an actuator, a third port fluidly coupled to a reservoir, and a fourth port configured to export a load-sense (LS) fluid signal. The valve can operate in: a neutral state, wherein fluid is allowed to flow from the second port to the third port, while the first port and the fourth port are blocked; a first actuated state, wherein fluid flow is throttled from the second port to the third port, while the first port and the fourth port remain blocked; or a second actuated state, wherein fluid flow from the second port to the third port is blocked, while fluid flow is allowed from the first port to the second port and from the second port to the fourth port.

Abstract: An auxiliary power unit system for mobile service vehicles is provided that can provide DC power to DC-powered equipment. The system attaches to the power take-off port of the transmission and can provide power to the DC-powered equipment without idling the engine of the mobile service vehicle, thereby reducing fossil fuel consumption and engine exhaust emissions.

Abstract: A large manipulator includes a chassis, a turntable arranged on the chassis and rotatable around a vertical axis via a rotary drive, and an articulated mast including two or more mast segments pivotably-movably connected, via articulated joints, with the respectively adjacent turntable or mast segment via a respective drive. The large manipulator further includes a mast sensor system configured to detect position of at least one point of the articulated mast or a pivot angle of at least one articulated joint and configured to generate sensor output signals. The large manipulator further includes a control device configured to actuate the drive in a normal operation for mast movement and to limit speed of movement of the articulated mast depending upon the sensor output signals. The drive is manually controllable in an emergency operation. The large manipulator further includes at least one limiting means, which, in the emergency operation, limit speed of the drive to a pre-specified maximum value.

Abstract: A liquid metal-cooled nuclear reactor includes, within a reactor pressure vessel, a primary electromagnetic pump (EMP) circulating liquid metal coolant through the reactor core and a backflow EMP. The nuclear reactor may be configured to at least partially mitigate liquid metal coolant backflow in response to a primary EMP failure. The backflow EMP is coupled in series with the primary EMP within the reactor pressure vessel. The backflow EMP may be selectively activated in response to failure of the primary EMP to mitigate liquid metal backflow through the primary EMP. The primary EMP and backflow EMP may receive power from separate power sources. Multiple backflow EMPs may be coupled in parallel to the primary EMP via parallel liquid metal coolant lines. A nuclear reactor may include multiple primary EMPs and multiple sets of backflow EMPs, where each separate set of backflow EMPs is coupled to a separate primary EMP.

Abstract: Provided is a slewing-type hydraulic work machine including a boom raising working pressure detection unit that detects boom raising working pressure, and a capacity control device that controls a slewing motor capacity during a slewing and boom-raising operation and performs detecting an actual slewing distribution factor correspondence value corresponding to a ratio of energy distributed to a slewing motor to energy of discharged hydraulic oil, setting a boundary value of the actual slewing distribution factor correspondence value to limit the ratio more with increase in boom raising working pressure, and a capacity operation of making the slewing motor capacity higher than a limit capacity within a slewing priority allowable period until the actual slewing distribution factor correspondence value reaches the boundary value during the slewing and boom-raising operation and limiting the slewing motor capacity to the limit capacity or less after the slewing priority allowable period.

Abstract: A hydraulic valve assembly includes a first spool valve and a first selector valve for actuating a first hydraulic consumer port or a second hydraulic consumer port, and a second spool valve and a second selector valve for actuating a third hydraulic consumer port or a fourth hydraulic consumer port. A shut-off valve is arranged in a common pressure channel. A branch channel with first and second pressure branch channels branches off the pressure channel upstream of the shut-off valve. The first selector valve connects the first pressure branch channel to a first connection line in a first switching position and connects the second pressure branch channel to a second connection line in a second switching position. The second selector valve, in a first switching position, connects the first connection line to the control channel and, in a second switching position, connects the second connection line to the control channel.

Abstract: To enable maintenance of a control valve in a narrow space, on a slewing frame an engine is disposed at a rear portion, a swivel joint is disposed between a pair of vertical plates, a slewing motor is disposed diagonally behind the swivel joint between the paired vertical plates, and a control valve is disposed diagonally behind the swivel joint between the paired vertical plates and forward of the engine. A detachment direction A of a plurality of spools of the control valve extends obliquely in such a way as to get closer to a right vertical plate as it goes rearward.

Abstract: A pump device includes a variable capacity first pump, a tilt actuator that controls a tilt angle of a swash plate of the first pump in accordance with the control pressure, a regulator that regulates the control pressure in accordance with a front-rear differential pressure of a control valve, a fixed capacity second pump driven by the same drive source as the first pump, the control actuator that operates in accordance with the front-rear differential pressure a resistor so as to drive the regulator to reduce the control pressure in response to an increase in the front-rear differential pressure of the resistor, an auxiliary passage that leads an auxiliary pressure to the control actuator, the auxiliary pressure acting on the control actuator against a upstream pressure of the resistor, and a switch valve that switches between connecting and shutoff the auxiliary passage.

Abstract: A method for forming hydraulic oil passages for hydraulic actuators according to an aspect of the present invention includes: forming a valve block mount surface including first and second regions on an outer surface of a housing; collecting valves for hydraulic actuators belonging to a main function group to a main function valve block that is mountable directly or indirectly on the first region; collecting valves for hydraulic actuators belonging to an additional function group to an additional function valve block that is mountable directly or indirectly on the second region; and mounting the valve blocks on corresponding regions of the valve block mount surface, and thereby, the hydraulic actuators to be mounted are fluidly connected to each other so that the hydraulic actuators are operable by using hydraulic oil from a common oil source.

Abstract: A construction machine that can easily regulate a set maximum flow rate at a time of replacement of an attachment and that can improve an energy conservation performance is provided. A controller selects a corresponding map in response to an attachment designation signal from among maps each of which sets a relationship between an operation signal per type of the attachment and a flow rate of a hydraulic fluid supplied to an actuator, generates a control signal by causing the selected map to refer to the operation signal, and controls a flow control valve of an attachment flow rate regulation valve device in such a manner that a position of the flow control valve is switched over from a neutral position on the basis of the control signal. An unloading valve that maintains a differential pressure across the flow control valve is disposed in the attachment flow rate regulation valve device.

Abstract: A hydraulic system for a work vehicle has a high pressure circuit for providing high pressure hydraulic fluid, a medium pressure circuit for providing medium pressure hydraulic fluid, and a low pressure hydraulic circuit for providing low pressure hydraulic fluid. The high pressure circuit has a variable displacement charge pump that provides pressurized hydraulic fluid only to a high pressure variable displacement pump according to demand, which provides the further pressurized hydraulic fluid to a priority valve according to demand. The medium pressure circuit has a medium pressure variable displacement pump that provides pressurized hydraulic fluid according to demand. The low pressure circuit has at least one low pressure variable displacement pump that provides pressurized hydraulic fluid by way of an oil cooler and/or an oil cooler bypass controlled by a proportional valve.

Abstract: A hydraulic system for a work machine includes a first control valve including a first direction switch to switch a direction in which the operation fluid is to flow through a first hydraulic actuator and a pressure compensator to maintain a differential pressure to a constant pressure, the differential pressure being a difference between a pressure of the operation fluid to be inputted to the pressure compensator and a pressure of the operation fluid to be outputted from the pressure compensator. And, the hydraulic system includes a second control valve including a second direction switch to switch a direction in which the operation fluid is to flow through a second hydraulic actuator and a flow rate prioritizer to prioritize a flow rate of the operation fluid to be outputted to the second hydraulic actuator.

Abstract: A hydraulic control system includes a variable displacement hydraulic pump, the pump having an inlet for receiving fluid, an outlet for discharging fluid under pressure, and a pump displacement input, a hydraulic motor having an inlet and an outlet a fluid circuit including a supply conduit for conducting fluid discharged by the pump to the motor and a return conduit for returning fluid discharged by the motor to the pump, a pump displacement control cooperating with the pump displacement input in order to vary a displacement of the pump, a control circuit in communication with the pump displacement control for controlling the pump output such that the motor is driven at a constant rotational speed and at least two valves controlling a rotational speed of the motor, wherein one of the valves provides coarser flow control resolution and another of the valves provides finer flow control resolution.

Abstract: A system and method for determining an orientation of a vehicle are provided. The system and method determine (with a sensor assembly disposed onboard a first vehicle) a direction in which a fluid flows within the first vehicle. The first vehicle is included in a vehicle consist with a second vehicle. The orientation of the first vehicle relative to the second vehicle is determined based at least in part on the direction in which the fluid flows within the first vehicle. The fluid may be air in an air brake pipe of the vehicle consist.

Abstract: A snow groomer having a frame; an attachment connected movably to the frame; a hydraulic assembly having an actuator configured to position the attachment, and a valve configured to control the actuator; a variable-flow pump configured to supply the hydraulic assembly; and a control system configured to calculate the total flow rate demand of the hydraulic assembly, and configured to control the variable-flow pump as a function of the total flow rate demand, so delivery by the variable-flow pump equals the total flow rate demand.

Abstract: A rotatory energy recycling control device for a hydraulic excavator, comprising: an oil line selector valve (1), a direction selector valve (2), a sequencing valve (3), a one-way valve (4) and an overflow valve (5); two oil inlets of the oil line selector valve (1) are respectively connected to an opening A and an opening B of a rotary motor; an oil outlet of the oil line selector valve (1) is connected to an inlet of the direction selector valve (2); an outlet of the direction selector valve (2) is connected to an net of the sequencing valve (3); a drainage port of the sequencing valve (3) is connected to an oil tank; an outlet of the sequencing valve (3) and an net of the one-way valve (4) communicate with the overflow valve (5): the outlet of the one-way valve (4) is connected to an energy storage and utilization device; and an outlet of the overflow valve (5) is connected to the oil tank.

Abstract: The present application relates to a switching valve, a switching hydraulic system, and a crane, in which the switching valve having an oil inlet and an oil outlet comprises at least two pairs of valve oil ports, a pair of cartridge valves provided between each pair of valve oil ports, and the oil inlet and the oil outlet are controlled such that the oil inlet and the oil outlet are capable of shifting between communications with the at least two pairs of valve oil ports. The switching valve switches on and off communication between the oil inlet and the oil outlet and the at least two pairs of valve oil ports by controlling opening or closing of the cartridge valves.

Abstract: A hydraulic driving system includes first to third liquid-pressure pumps and control valves. The first boom control valve is connected to the first hydraulic pump, and the second arm control valve and the first bucket control valve are connected to the second liquid-pressure pump. Further, the turning control valve and the second bucket control valve are connected to the third hydraulic pump. When a pilot pressure XAk0 is output from a bucket operating device while a turning operation is performed, a command switching device outputs a pilot pressure XAk1 to the first bucket control valve. When the pilot pressure XAk0 is output from the bucket operating device while the turning operation is performed, the command switching device outputs a pilot pressure XAk2 to a second bucket control valve.

Abstract: A pump discharge amount is divided in accordance with switch amounts of respective switch valves by leading load pressures of actuators to which compensator valves are connected to respective first pressure chambers of the compensator valves, leading a maximum load pressure selected by a selection unit to respective second pressure chambers of the compensator valves, and controlling respective openings of the compensator valves in accordance with respective pressure actions between the respective pressure chambers. A drain passage is provided to connect the first pressure chamber of the compensator valve to a tank, and a flow dividing ratio modification valve is provided to control a pressure in the first pressure chamber.

Abstract: An industrial vehicle includes a hydraulic mechanism, an operation lever, and a pump, a hydraulic control valve unit, a lever operation detector, an internal combustion engine controller, and a valve controller that controls the hydraulic control valve unit. When the lever operation detector detects the operation of the operation lever under a situation in which a speed of the internal combustion engine is less than or equal to a predetermined speed, the valve controller operates the hydraulic control valve unit to discharge the hydraulic oil without supplying the hydraulic oil to the hydraulic mechanism and instructs the internal combustion engine controller to increase the speed of the internal combustion engine, and subsequently operates the hydraulic control valve unit to supply the hydraulic mechanism with the hydraulic oil.

Abstract: A shovel may be provided with a swing hydraulic motor, a relief valve provided on the swing hydraulic motor, and an accumulator part that supplies to the swing hydraulic motor a working oil having a pressure lower than a relief pressure of the relief valve. The accumulator part may accumulate the working oil on a braking side of the swing hydraulic motor. The accumulator part may discharge the working oil to an upstream of a main pump.

Abstract: Provided is a slewing drive apparatus for a construction machine capable of satisfactory pump-flow-rate control regardless of change in engine speed, including a variable displacement hydraulic pump, a slewing motor, a slewing operation device, a control valve, a relief valve, and a pump-flow-rate control device that performs a relief cut control and includes: a section for detecting an engine revolution number Ne and a slewing speed of a slewing body; a section for determining a target pump flow rate Qo that is a sum of a slewing-speed correspondence flow rate Q1 and a minimum required relief flow rate Qmin; a section for determining a target pump-tilt-angle qtg obtained by dividing the target pump flow rate Qo by the detected engine revolution number Ne; and a section for adjusting an actual pump-tilt-angle of the hydraulic pump so as to bring the actual pump-tilt-angle to the target pump-tilt-angle qtg.

Abstract: A hydraulic arrangement for supplying a consumer or actuator includes a first supply device that has at least one pump with an adjustable delivery volume. The hydraulic arrangement further includes a second supply device that is connected in parallel to the first supply device. The second supply device includes a loadable accumulator and a digitally regulated switching valve arrangement.

Abstract: An engine fuel control system includes a fuel metering valve that controls the flow of fuel between supply and delivery lines which delivers fuel to engine burners. The fuel control system includes a fixed displacement main pump which receives fuel from a low pressure source and delivers the fuel at a first high pressure to the supply line, an augmenter pump which receives fuel from the low pressure source and delivers the fuel at a second high pressure to one or more fuel-pressure operated auxiliary engine devices, and a start valve which is actuated at low engine speeds to open a flow path which diverts fuel delivered by the augmenter pump away from the auxiliary engine devices to the supply line to augment the fuel delivered thereto by the main pump, the start valve being actuated at higher engine speeds to shut the flow path.

Abstract: A construction machine includes: a swing structure (20); hydraulic and electric motors (25) mechanically coupled to each other; a hydraulic pump (41) that supplies hydraulic fluid to the hydraulic motor; swing control lever (72) that instructs the swing structure to make a swing motion; and a control device (80) that controls at least either a delivery flow rate of the hydraulic pump or an output torque of the electric motor in such a manner that meter-out and meter-in pressures of the hydraulic motor that is run together with the electric motor approach each other when the demanded torque necessary for the swing motion of the swing structure instructed by the swing control lever can be produced by the electric motor alone.

Abstract: In open-circuit hydraulic systems (1), the cross-sections of the supply lines (6) and input valves of the hydraulic pump (3) have to be large, so that sufficient flow flux can be provided. This hinders a reduction of the size of the pump and the whole hydraulic system. It is suggested that the supply flow (7) of a hydraulic pump (3) is charged by a second, charging pump (2), to a mid-pressure level (7). The cross-sections of the supply flow areas can thus be decreased.

Abstract: A hydraulic control device for a work vehicle includes: a hydraulic pump that supplies pressure oil; an arm drive actuator that drives, with pressure oil supplied from the hydraulic pump, an arm attached to the work vehicle so as to swing the arm; a bucket drive actuator that drives, with pressure oil supplied from the hydraulic pump, a bucket attached to a front end of the arm, so as to swing the bucket; an arm drive pressure oil control valve that controls drive of the arm drive actuator by controlling pressure oil supplied from the hydraulic pump to the arm drive actuator; a bucket drive pressure oil control valve that controls drive of the bucket drive actuator by controlling pressure oil supplied from the hydraulic pump to the bucket drive actuator; an arm operation unit that controls the arm drive pressure oil control valve; a bucket operation unit that controls the bucket drive pressure oil control valve; an operating state detection unit that detects operating states of the arm drive actuator and the

Abstract: A hydraulic additional drive includes a hydraulic or having working ports configured to be connected to a pump via a high pressure branch and a low pressure branch. The hydraulic motor further includes a purging port to which a feed pressure is configured to be applied to set a “free-wheel mode” while the working ports are connected to a tank. The pressure at the purging port is limited to a comparatively low value between the feed pressure and the tank pressure by a pre-charging valve integrated into the hydraulic motor. The pre-charging valve is arranged in a free-wheel duct which hydraulically connects the purging port to one of the working ports.

Abstract: A method is provided for controlling a hydraulic system having at least an implement pump, a fan-steering-braking (FSB) pump, a valve assembly, a fan drive system and one or more accumulators. The method may determine an operational state of a power source associated with the hydraulic system, actuate one or more valves of the valve assembly such that the FSB pump charges the accumulators and operates at least the fan drive system if the power source is operating at less than maximum power, and actuate one or more valves of the valve assembly such that the accumulators operate at least the fan drive system and such that the FSB pump supplements the implement pump as needed if the power source is operating at maximum power.

Abstract: A hydraulic pump control system provided in a construction machine such as an excavator is provided. According to the hydraulic pump control system, a loss of a flow rate is reduced by initially supplying hydraulic fluid as much as necessary from a hydraulic pump to a hydraulic motor in order to accelerate a swing movement of an upper frame against a lower traveling structure or to make an upper swing structure swing.

Abstract: A hybrid-type construction machine comprises an engine 11; an electric power accumulator 19B; first and second pumps 28, 14; a motor generator 27 for driving the first pump 28; and plural actuators 1A, 1B, 7, 8 and 9 which are driven by the first and second pumps 28, 14, wherein the first and second pumps 28, 14 are arranged such that the first pump 28 controls at least one of the actuators 1A, 1B, 7, 8 and 9 independently from the second pump 14 and the second pump 14 controls at least another one of the actuators 1A, 1B, 7, 8 and 9 independently from the first pump 28, the first pump 28 is electrically driven by the motor generator 27 with electric power from the electric power accumulator 19B, and the second pump 14 is directly coupled to the engine 11.

Abstract: A method for controlling the operation of at least one hydraulic component of a work vehicle may generally include storing, with a computing device, a first electro-hydraulic setting and a second electro-hydraulic setting for the hydraulic component. The first electro-hydraulic setting may be associated with at least one of a pre-defined speed setting or a pre-defined sensitivity setting. The second electro-hydraulic setting may be associated with at least one of an operator-defined speed setting or an operator-defined sensitivity setting. In addition, the method includes receiving an input associated with an operator's selection of the first electro-hydraulic setting or the second hydraulic setting, and controlling the operation of the hydraulic component in accordance with the first electro-hydraulic setting or the second electro-hydraulic setting based on the operator's selection.

Abstract: According to the present disclosure, a hydraulic control apparatus for construction machinery comprises: hydraulic pumps; first and second control valve units which control the flow directions of working oil discharged from the hydraulic pumps to supply the working oil to first and second work machines, respectively, and which control the degree of opening of flow channels which interconnect the first and second work machines and the hydraulic pumps, respectively; and a control unit which controls the first and second control valve units in accordance with operating signals inputted from first and second operating units.

Abstract: A hydraulic system includes a variable-displacement first pump, an over-center variable-displacement first travel motor selectively connected to receive fluid pressurized by the first pump in a closed loop manner, and an over-center variable-displacement second travel motor selectively connected to receive fluid pressurized by the first pump in parallel with the first travel motor in a closed loop manner. The hydraulic system also includes a linear actuator selectively connected to receive fluid pressurized by the first pump in parallel with the first and second travel motors in a closed loop manner.

Abstract: A hydraulic control system is provided in which hydraulic oil discharged from a variable displacement hydraulic pump is controlled and supplied to a hydraulic actuator by a closed center control valve activated based on operation input from an operation device, thereby controlling activation of the hydraulic actuator. With the pump displacement detected by pump displacement detecting means and the pump output pressure detected by pump output pressure detecting means being used as feedback input and the characteristic value determined by the operation input and the feedback input being used as a target value of a control loop, variable displacement control is performed by a controller provided with a horsepower control loop, a pressure control loop, a flow rate control loop, and a minimum pressure holding loop that feed back a calculated value based on the feedback input or the feedback input itself.

Abstract: A flexible response secured mechanical balancing device (D) for multiple hydraulic control actuators (1-2) with a common output member (5a-b). The balancing device (D) provides flexible/continuous fluid-pressure force fight compensation. Balance valves (17-20) are commanded to balance fluid-pressure from a first fluid-pressure network (52a) of a second actuator (2). Each fluid-pressure commanded balance valve (17-20) is arranged to allow relief of differential pressure, directly into a dedicated first (52a) or second fluid-pressure network (52b). A fluid-pressure controlled locking device (21-22) is allowing inhibiting the corresponding pairs of balance valves (17-20) e.g. in case of loss of fluid-pressure. The invention typically applies to vehicles (A) including: aircrafts, rotorcrafts, drones.

Abstract: A hydraulic system for a machine is disclosed. The hydraulic system may have a tank configured to hold a supply of fluid, a pump configured to draw fluid from the tank and pressurize the fluid, a first cylinder operatively connected between a first side of a work tool and an undercarriage of the machine, and a second cylinder operatively connected between a second side of the work tool and the undercarriage of the machine. The hydraulic system may also have a first electro-hydraulic valve associated with the first cylinder and configured to selectively regulate a flow of pressurized fluid to the first cylinder independently of the second cylinder, and a second electro-hydraulic valve associated with the second cylinder and configured to selectively regulate a flow of pressurized fluid to the second cylinder independently of the first cylinder.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a unidirectional variable displacement first pump, a first actuator connected to the first pump via a closed-loop first circuit, and a first switching valve disposed between the first actuator and the first pump. The first switching valve may be configured to control a fluid flow direction through the first actuator. The hydraulic system may also have a second actuator connected to the first pump in parallel with the first actuator via the first circuit, and a second switching valve disposed between the second actuator and the first pump. The second switching valve may be configured to control a fluid flow direction through the second actuator. The hydraulic system may further have a modulation valve associated with the first circuit and configured to selectively modulate a pressure of the first circuit during actuation of the first or second switching valves.

Abstract: A hydraulic system for a construction machine having a pressure compensation valve is disclosed, which improves operability when a combined operation of a swing device and an attachment is performed.