Abstract: Parasitic hydraulic loading on an engine is significantly reduced during cold starts by using an unloader valve to divert the flow of hydraulic fluid from a hydraulic pump to a hydraulic actuator, i.e., load source, recirculating the hydraulic fluid between the hydraulic pump and the unloader valve.

Abstract: A hydraulic system for a work vehicle is disclosed. A preferential flow-dividing valve supplies a fixed amount of oil discharged from a variable displacement pump preferentially to a preferential hydraulic oil section and a surplus oil flow from the pump to a non-preferential hydraulic oil section. A plurality of electromagnetic proportional control valves are provided in the non-preferential hydraulic oil section for controlling oil flows relative to a plurality of hydraulically operated devices provided in the non-preferential hydraulic oil section. A necessary flow rate calculating module calculates a necessary oil flow rate in each of the preferential hydraulic oil section and the non-preferential hydraulic oil section based on a preferential oil flow rate of the preferential flow-dividing valve supplied to the preferential hydraulic oil section and an amount of current distributed to each of the plurality of electromagnetic proportional control valves in the non-preferential hydraulic oil section.

Abstract: A solenoid pump and associated hydraulic circuitry are intended for use in automatic transmissions capable of engine start stop (ESS) operation. In a first embodiment, a solenoid pump provides pressurized hydraulic fluid to respective inputs of two way check valves. The other inputs are provided with controlled hydraulic fluid from a transmission valve body. The outputs of the check valves are provided to those hydraulically operated torque transmitting devices associated with first gear. The solenoid pump is activated when the transmission is in gear and the engine is stopped to maintain hydraulic pressure in those actuators associated with first gear in order that a first gear vehicle launch may be quickly and smoothly achieved when the engine is restarted. A second, similar embodiment provides hydraulic fluid to actuators associated with reverse gear.

Abstract: The present invention provides a construction machine where overheating of mounted electric devices can be prevented properly with a simple structure and a method of controlling the construction machine. For this purpose, a pump target discharge flow rate of a hydraulic pump is calculated based on an operated amount of an operating unit, a temperature of an electric device mounted on the construction machine is detected, an engine minimum speed, which is a minimum possible speed of an engine in carrying out low-speed matching for matching output of the engine and pump absorbing horsepower of the hydraulic pump to each other in a low-speed region where speed of the engine is lower than set speed, is calculated by using the detected temperature of the electric device, and a maximum value out of a corresponding speed of the pump target discharge flow rate and the engine minimum speed is generated as a candidate for an engine target speed.

Abstract: A hydraulic implement system for a machine is disclosed. The hydraulic implement system may have a boom member, a boom actuator, and a boom operator control device movable to indicate a related operator desired boom member velocity. The hydraulic implement system may also have an implement pivotally connected to the boom member, an implement actuator, and an implement operator control device movable to indicated a related operator desired implement velocity. The range of the implement operator control device may be divided into a first portion and a second portion. The hydraulic implement system may also have a controller configured to selectively limit a velocity of the implement during manipulation of the implement operator control device within the first portion such that a lift velocity of the boom member of at least 65% of the desired boom member velocity is always possible.

Abstract: A combination of a piston and a chamber, wherein the chamber defines an elongate chamber having a longitudinal axis, the chamber having, at a first longitudinal position thereof, a first cross-sectional area thereof and, at a second longitudinal position thereof, a second cross-sectional area, the second cross-sectional area being 95% or less of the first cross-sectional area, the change in cross-section of the chamber being at least substantially continuous between the first and second longitudinal positions, the piston being adapted to adapt itself to the cross-section of the chamber when moving from the first to the second longitudinal position of the chamber. The piston may comprise an umbrella-like support structure or a fiber enforced deformable container comprising a foam or a fluid. The combination may be used in a pump, a linear actuator, a motor, or a shock absorber.

Abstract: A variable pressure control system for varying pressures in the fluid circuits of a dual acting actuator over a range of pressures. The variable pressure control system includes a controller that cooperates with pressure regulators for regulating the desired pressure in the fluid circuits.

Abstract: The invention relates to a hydraulic apparatus comprising a hydraulic pump (30) which is connectable to a hydraulic fluid tank, an electric motor (2) as a drive means for the hydraulic pump (30), which electric motor comprises a motor shaft and a motor housing cover (4), and a control valve assembly (12) connected to the pump (30) to control at least one hydraulic consumer which is connectable to the pump (30) and is to be supplied by the pump (30) with hydraulic fluid from the hydraulic fluid tank, wherein the pump (30) is fixed on the motor housing cover (4) and the motor housing cover (4) comprises a holding adapter (10) on which the control valve assembly (12) is fixed.

Abstract: A hybrid working machine includes an engine, an assist motor configured to assist the engine, a hydraulic pump driven by the engine, an electric power accumulating unit configured to feed the assist motor with electric power, an electric-discharge electric motor configured to perform power running with electric power of an electric power accumulator of the electric power accumulating unit, an electric-discharge hydraulic motor connected to the electric-discharge electric motor, and a hydraulic circuit configured to control driving of the electric-discharge hydraulic motor. The hydraulic circuit includes a circulation circuit configured to be connected to a hydraulic feed port and a hydraulic discharge port of the electric-discharge hydraulic motor and a selector valve configured to perform such switching as to connect the electric-discharge hydraulic motor to the circulation circuit at a time of performing an electric discharge operation.

Abstract: A power transmission device that transmits power from a motor to a wheel via a hydraulically driven friction engagement element and that includes a mechanical pump driven by the motor to produce a hydraulic pressure that is regulated by a pressure regulating valve; an electric pump that produces a hydraulic pressure; a switching mechanism that either switches an output pressure of the regulating valve or an output pressure of the electric pump to a servo of the engagement element based upon a signal pressure, and a drain valve that opens to drain oil when a hydraulic pressure of a preset pressure or more is applied, and the switching mechanism connects to the drain valve to allow communication between the electric pump and the drain valve in the first state, and shut off communication between the electric pump and the drain valve.

Abstract: In a work machine including a hydraulic pump (1), a swing motor (2), and swing relief valves (3a and 3b), the amount of the swing operation (P1) related to the swing motion of the swing motor (2) is detected, and the hydraulic pressure (P2) supplied from the hydraulic pump (1) to the swing motor is also detected. Additionally, the required flow rate (FR) of hydraulic oil required for the swing motor (1) is set based on the amount of the swing operation (P1). In addition, the volume of relief (FE) is estimated from the hydraulic pressure (P2) based on the override characteristics of the swing relief valves (3a and 3b). The discharge flow rate of the hydraulic pump (1) is controlled based on the value obtained by subtracting the volume of relief (FE) from the required flow rate (FR).

Abstract: A hydraulic circuit is provided having a hydraulic actuator and a flow control valve. The flow control valve has a pressure adjusting element fluidly coupled to the hydraulic actuator and situated to affect a pressure of fluid being directed to the hydraulic actuator. The flow control valve also has an energy directing element operatively coupled to the pressure adjusting element and situated to be driven by the pressure adjusting element when the pressure adjusting element is selectively throttling fluid being directed to the hydraulic actuator.

Abstract: A hydraulic fan circuit is disclosed. The hydraulic fan circuit may have a primary pump, a motor, a fan connected to and driven by the motor, and a flywheel connected to and driven by one of the motor and the fan. The hydraulic fan circuit may also have a supply passage extending from the primary pump to the motor, a return passage extending from the motor to the primary pump, and a diverter valve configured to selectively connect the supply passage to a low-pressure sump.

Abstract: An actuator in which overshooting has been reduced is provided. A cylinder is divided by a piston to provide first and second chambers, and first and second control valves 41, 43, which adjust fluid pressure supply to respective chambers in a non-step manner, and first and second discharge valves 42, 44, which control outflow of fluid from the first and second chambers, are provided. A first control device carries out feedback control of pressure to be supplied to the first or second chamber such that a difference between a target position of the piston and a detected position of the piston becomes smaller. A second control device carries out differential-preceding PD control to bias pressure to be commonly supplied to the first and second chambers such that the difference between the target position of the piston and the detected position of the piston becomes smaller.

Abstract: A hydraulic system, especially in a high-pressure application, comprises a pressurized-fluid tank, a pressurized-fluid pump driven by a drive unit, at least one hydraulic load that can be pressurized thereby and a control and/or distribution unit connected fluidically between the pressurized-fluid pump and the load. This unit is provided with a housing and a core received therein and connected rigidly with the housing, which core bears with part of its surface in the region of a common, closed, especially cylindrical joint face with the housing on a corresponding inside face of a housing opening. Surface groove-like flow ducts are provided on the core and/or the housing in the region of the joint face, and the pressurized-fluid pump is directly built onto the control and/or distribution unit in the region of a free end face of the core.

Abstract: A three-dimensional measuring machine (industrial machine) includes an air supplier supplying air; a drive mechanism driven by the air supplied from the air supplier; an electromagnetic valve provided inside an air regulator set to open and close an air supply passage inside the air regulator set, the air regulator set introducing the air from the air supplier to the drive mechanism; and a motion controller controlling the electromagnetic valve to block the air supply passage when a time since the drive mechanism stopped operation reaches a preset time.

Abstract: A method of detecting a fluid leak in a hydraulic fluid circuit includes preventing fluid from entering the circuit when an actual outlet flow rate from a pump is positive while a requested outlet flow rate to a hydraulic machine is zero. An outlet port of a variable displacement port can be selectively blocked, while in a fixed displacement pump (FDP) fluid can be diverted from the outlet port to a secondary fluid circuit. The actual outlet flow rate can be measured using a flow sensor or a swash plate angle depending on the pump design. A hydraulic fluid circuit includes a hydraulic machine, a pump, a valve at an outlet port of the pump, and a controller. The controller determines the requested flow rate, and actuates the valve to prevent fluid from entering the circuit whenever the actual outlet flow rate is positive during zero requested flow rate.

Abstract: A hydraulic control circuit includes an oil pump for generating a hydraulic pressure by being rotated by power of a driving force source, a line pressure oil passage in which at least a line pressure generated by adjusting the hydraulic pressure generated by the oil pump is supplied, a driving force source stopping unit that stops the rotation of the driving force source, and a hydraulic pressure reduction suppressing unit that is provided in the line pressure oil passage and suppresses a reduction of the line pressure accompanying reverse rotation of the driving force source when the rotation of the driving force source is stopped by the driving force source stopping unit.

Abstract: A hydroelectric turbine generator and control system is provided that optimizes the maximum possible power output at all times by strictly monitoring power output from the generator unit and modulating the wicket gate angle and the runner blade pitch independently of one another. The hydroelectric turbine generator includes a means for separately controlling wicket gate angle and runner blade pitch. The wicket gate angle control mechanism controls the flow into the system, pre conditions flow for maximum power and maintains reservoir level. The runner blade pitch control mechanism continuously monitors the system power output based on actual power produced, and adjusts system parameters in order to achieve maximum power output.

Abstract: A hydraulic pump driven by an engine, a hydraulic actuator, and a negative control circuit are provided on an open center hydraulic circuit, for guiding the hydraulic pressure in the center bypass to the hydraulic pump, as a negative control pressure. A negative control pressure control device controls the negative control pressure to an arbitrary value is also provided. The pump characteristic of the hydraulic pump is set such that the discharge flow rate is minimized when the negative control pressure in the negative control circuit is equal to or greater than a first predetermined pressure. Furthermore, an idling detection device that detects whether the hydraulic actuator is in a non-operated state or not is provided. The negative control pressure is forcefully controlled to the first predetermined pressure or higher when the non-operating state is detected.

Abstract: An axial bearing between a first part and a second part that presses with an axial load against the first part and can rotate around a rotation axis relative to the first part comprising a circular or arc-shaped ridge on the first part centered around the rotation axis, a pressure source for providing pressurized hydraulic fluid on a first side of the circular or arc-shaped ridge, an adjustable gap between the circular or arc shaped ridge and a bearing surface on the second part, wherein the pressurized hydraulic fluid flows through the adjustable gap to a second side of the circular or arc-shaped ridge. In accordance with the invention the circular or arc-shaped ridge or the bearing surface include a ridge chamber for locally creating a larger adjustable gap between the circular or arc-shaped ridge and the bearing surface.

Abstract: A fluid working machine comprises a working chamber of cyclically varying volume, a high pressure manifold, and an actuated high pressure valve for regulating the flow of fluid between the working chamber and the high pressure manifold. The actuated high pressure valve comprises a moveable valve member, operable between a closed position and at least one open position. A controllable opening mechanism provides an active urging force to urge the moveable valve member from the said closed position towards at least one said open position, the volume of the working chamber varying between a maximum volume and a minimum volume. The controllable opening mechanism provides the active urging force more than once while the volume of the working chamber is intermediate the maximum of chamber volume and the minimum of chamber volume.

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

Abstract: A hydraulic device includes a switch-over valve 1140 provided at a section of a sub-passage 1105 located downstream of a location where a first bypass passage 1117 is connected and located upstream of a primary regulator 1110. The switch-over valve 1140 is switched between a blocked state, where supply of hydraulic oil to a section of the sub-passage 1105 located downstream of the switch-over valve 1140 is blocked, and a communication state, where supply of hydraulic oil to the section of the sub-passage 1105 located downstream of the switch-over valve 1140 is permitted. In the hydraulic device, when the switch-over valve 1140 is switched to the communication state, as a discharge performance of a main pump 1102 increases, a first check valve 1118 closes. Supply paths for hydraulic oil discharged from the sub-pump 1103 are automatically switched in accordance with the discharge performance of the main pump 1102.

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

Abstract: An electro-hydraulic actuator (EHA) includes a hydraulic circuit having a plurality of pressure compensated flow control valves for allowing a maximum flow rate through the fluid conduits regardless of the loads imparted on the actuator. In one embodiment of the EHA, a plurality of combination manual override/thermal expansion valves that simplify the manufacture of the EHA.

Abstract: A vehicle comprises a chassis and a tilt cab which is mounted to said chassis and is tiltable with respect to the chassis. The vehicle furthermore comprises a tilting system for tilting said tilt cab relative to the chassis between a lowered position and a raised position. The tilting system comprises a reservoir for hydraulic fluid, a pump and at least one double-acting hydraulic tilt cylinder having a push chamber and a pull chamber. The cylinder has a movable piston and piston rod assembly, wherein the piston separates the push chamber and the pull chamber. The cylinder is connected to the chassis and to the cab, such that when hydraulic fluid is supplied to the push chamber the cab moves to the raised position and when hydraulic fluid is supplied to the pull chamber the cab moves to the lowered position.

Abstract: An embodiment in accordance with the present invention provides a hydraulic pump including a first motor running at a fixed speed, a reservoir for fluid and a first pump operatively coupled to the motor such that the pump runs at the same speed as the motor and generates a flow of fluid from the reservoir. The hydraulic pump further includes a second motor, a speed control valve operatively coupled to the to the first pump and operatively coupled to the second motor such that a portion of the flow is directed to the second motor and the remainder of the flow is diverted to the reservoir, and a second pump operatively coupled to the second motor such that the second pump is driven by the second motor.

Abstract: Actuator for emergency opening of an openable element (Co) of an aircraft, having: a thrustor (1) arranged to be connected, at one (3) of its ends, to said openable element and, at its other end (4), to a reference element (Re) of the aircraft to which said openable element is linked, a pressurised-gas reservoir (2), said gas reservoir (2) having a membrane (6) capable of being perforated in order to actuate said thrustor for the purpose of emergency opening of the openable element by release of the gas from the reservoir, a movable perforator (7) arranged to perforate said membrane of said reservoir in order to release the gas contained in the latter into the thrustor via a first fluid circuit (8), means (9) for venting, away from the thrustor, the gas contained in the reservoir, in the event of accidental rupture of said membrane, via a second fluid circuit (10) which does not actuate said thrustor.

Abstract: A hydraulic hitch system for a vehicle includes a hydraulic source, a hydraulic reservoir, a hydraulic cylinder, an operator-controlled actuating means for generating a command signal, a hydraulic control valve for controlling the hydraulic cylinder, and an electronic control unit for controlling the control valve. To make it easier for the operator to set the hydraulic functions when working with different attachments, a pressure sensor generates a pressure signal and is connected to the hydraulic cylinder, and a control device is used to select a pressure control program for the hydraulic cylinder. The control valve is activated by a control signal which is generated by the control unit as a function of the selected pressure control program, the pressure signal and a command signal generated by the control device.

Abstract: A swing motor control method in an open center type hydraulic system for a hydraulic excavator is provided, which can adjust the speed of a swing motor so that a swing device and a working device harmonize with each other according to a discharge pressure of a hydraulic pump during a multifunctional work of the working device and the swing device.

Abstract: A method for actuating a bypass control valve assembly of a fluid system includes receiving a first input signal at an electronic control unit. The first input signal is related to an active position of a direction control valve that is in fluid communication with a fluid pump and a fluid actuation device. The directional control valve includes a neutral position that provides fluid communication between a fluid inlet port of the directional control valve and a fluid outlet port of the directional control valve. A second input signal is received at the electronic control unit. The second input signal is related to the rotational speed of the fluid pump. The second input signal is compared to a limit. A drain valve of a bypass valve assembly is actuated so that fluid communication between the fluid pump and a fluid reservoir through the bypass valve assembly is blocked.

Abstract: The disclosure describes, in one aspect, a control system for charging an electro-hydraulic charging system. The control system including at least one sensor operatively coupled to an engine for sensing at least one engine parameter indicative of an operating status of the engine and a controller adapted to charge the charging system when the operating status of the engine is determined to be stable.

Abstract: The invention relates to a hydraulic system, having a hydrostatic, valve-controlled piston engine with a plurality of valves actuatable by an actuator as a function of the motion of the pistons, and with a control unit for triggering the actuators, which is arranged for generating an electrical attraction current in a first time segment and a maintenance current in a second time segment. The object of the invention is for the valves to switch with quick reactions and function safely, so that the expected functionality and safe operation of the hydrostatic piston engine under various operating conditions is ensured. This is attained in that the control unit includes a current regulating device, which triggers the actuators in current-regulated fashion.

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: A power system for a lift gate is provided. The power system includes an actuator system including an actuator for a lift gate, and a lift gate engine coupled to the actuator system. The lift gate engine is configured for generating kinetic energy from a fuel source to power the actuator system for operating the lift gate.

Abstract: A control unit of a hydraulic brake apparatus for a vehicle including a housing, a switching control valve, pressure increase control valves, pressure decrease control valves, a reservoir, a pump driven by a motor, a first passage, a second passage, an inner bore and a passage forming member being liquid-tightly fitted into the inner bore in order to form an extended ring-shaped passage, wherein the extended ring-shaped passage forms a part of the first passage, and the switching control valve, the pressure increase control valves and the outlet valve are connected to the extended ring-shaped passage, and a part of the second passage is formed within the passage forming member, and end portions of the part of the second passage are connected to the switching control valve and the switching valve.

Abstract: A compressed air supply device is provided for a utility vehicle, having a compressor which can be driven by a drive via a pneumatically switchable clutch, and a valve which can be activated by an electrical signal in order to optionally feed compressed air to a switching inlet of the clutch. The compressed air, which is fed to the switching inlet via the valve, is extracted from a compressed air preprocessing system via a non-return valve.

Abstract: Methods and systems for operating a cylinder lock valve to control fluid flow to a hydraulic cylinder operating a drilling rig sub-system. The lock valve 1) allows fluid flow through the valve if pressure on a main and pilot area overcomes a closing spring force on the valve, or 2) blocks flow through the valve if a loss in charge pressure in the main and pilot area falls below the closing spring force on the valve.

Abstract: Hydraulic transmission system for a mineral material processing plant, which transmission system comprises at least two hydraulic first motors, which are arranged to drive at least one conveyor belonging to the mineral material processing plant, at least two first directional valves connected via the first actuator channels of the directional valves to each of the first motors, a hydraulic pump arranged to transfer hydraulic fluid via the first actuator channels of the directional valves to the first motors. The system also comprises pressure sensors. The first directional valves are valves that can be adjusted by external control during the running of the processing plant and which are arranged to control the volume flow of the hydraulic fluid supplied into the first motors. The control is made on the basis of the pressure of hydraulic fluid measured by pressure sensors in the first actuator channels the directional valves.

Abstract: The invention relates to a hydrostatic drive system having a pump (1) and at least one consumer (6) that can be connected alternately to the pump (1) and to a tank (3) by means of a directional control valve (4) that can be actuated by control signals (15, 16), in order to control the motion of a positive or a negative load (9) at the consumer. Provision is made to this effect that there is disposed in the line (13) of the negative connection of the consumer that leads via the directional control valve (4) to the tank (3) a pre-charge valve (5, 51, 60) that can be placed under a pressure that can be controlled via a programmable logic unit (31) when controlling a positive load.

Abstract: The hydraulic pressure control apparatus includes an upstream control valve, a downstream control valve, a hydraulic pressure sensor, and a controller. The upstream control valve is provided between a hydraulic pressure source and a hydraulic pressure device. The downstream control valve is disposed between the upstream control valve and the hydraulic pressure device. The hydraulic pressure sensor is configured and arranged to detect the hydraulic pressure on a downstream side of the downstream control valve. The controller is configured to control the upstream control valve and the downstream control valve based on an upstream pressure command value and a downstream pressure command value, respectively. The controller is further configured to detect an abnormality in the upstream control valve based on the hydraulic pressure detected by the hydraulic pressure sensor when the downstream pressure command value is set to be equal to or greater than the upstream pressure command value.

Abstract: A method of controlling a machine having a hydraulically actuated linkage includes lowering a load suspended by the leakage at least in part by leaking hydraulic fluid from a portion of a hydraulic actuation system, and generating a drift compensation control signal responsive to leaking hydraulic fluid. A machine includes an electronic controller in control communication with a valve, the electronic controller being configured to compensate for leakage induced drift of at least one hydraulic actuator of a machine hydraulic system by selectively commanding adjusting of the valve if drift criteria for the hydraulic system are satisfied.

Abstract: A loader includes a hydraulically operated extension arm, a load sensor for monitoring the load condition on the loader and a hydraulic arrangement for actuation of the extension arm and/or an implement attached to the extension arm. The hydraulic arrangement exhibits at least one hydraulic cylinder with one supply line on the piston rod side and one supply line on the piston side. At least one mechanically switchable control device is coupled between a source of fluid pressure and a hydraulic tank, on the one hand, and the supply lines on the other hand. An electronic control unit is connected for effecting operation of a restricting device coupled between the supply lines in response to a load signal received from the load sensor so as to achieve a slowed-down actuation of the hydraulic cylinder in conjunction with the on set of a critical load condition.

Abstract: In the oil pressure system, a control unit sets a flow passage changeover valve to be in a merging state, and sets a relief pressure to a low relief pressure via a relief pressure changeover unit in the case that the rotational speed of the engine is lower than a predetermined threshold level. Also, the control unit sets the flow passage changeover valve to be in a branching state, and sets the relief pressure to a high relief pressure via the relief pressure changeover unit in the case that the rotational speed of the engine is the predetermined threshold level or higher.

Abstract: A ground engaging vehicle including a movable member, a hydraulically driven actuator, a hydraulic pump, a plurality of valves and at least one hydraulic conduit. The hydraulically driven actuator is coupled to the movable member and the actuator has a first chamber and a second chamber. The plurality of non-proportional valves include a first valve, a second valve, a third valve and a fourth valve. The at least one hydraulic conduit couples the pump with the first valve and the second valve. The first valve is in direct fluid communication with the first chamber. The second valve is in direct fluid communication with the second chamber. The third valve is in direct fluid communication with the first chamber and the fourth valve is in direct fluid communication with the second chamber. The first valve and the second valve each include an open position and a closed position.

Abstract: In a hydraulic control device H comprising a pressure source P which can be switched on and switched off, a reservoir R and a pressure switch W located in a discharge path 13 from a valve assembly V to the reservoir R, which pressure switch W either connects the valve assembly V with the reservoir R or blocks the valve assembly V versus the reservoir R, the pressure switch W contains a displaceable control member 16 which is actuated in a first switching direction by a spring 17 and a pilot pressure originating from the pressure P1 acting at the valve assembly V and in a second switching direction to a control position blocking the discharge path 13 by a pilot pressure originating from the supply pressure of the pressure source, the pressure switch W is designed as a 2/2-multi-way seat valve 16 operating with a blocking position without leakage. A valve member 24 forms the control member 16 and co-operates with a valve seat 25 arranged in the discharge path 13.

Abstract: A method for controlling a working machine including a hydraulic system for controlling a plurality of work functions, including lift and tilt of an implement, includes the steps of determining a maximum pressure of a hydraulic fluid for performing a certain task with the implement individually for at least one of the work functions, and delivering the hydraulic fluid, pressurized at most to the determined maximum pressure, to the work function.

Abstract: A method for controlling a hydraulic system includes receiving an operator command signal via an operator command input device; receiving a throttle position signal from a throttle; retrieving from a memory a first predetermined correlation between the operator command signal and a corresponding command flow rate; retrieving from the memory a second predetermined correlation between the throttle position signal and a corresponding available flow rate from a hydraulic pump; determining the command flow rate based on the first predetermined correlation and the operator command signal; determining the available flow rate based on the second predetermined correlation and the throttle position signal; and providing a control signal based on the available flow rate and the command flow rate.