Abstract: A hydraulic actuator includes a switching part that is provided with an oil passage for sending pressurized oil generated by a hydraulic pump to a tool and returning return oil from the tool to the hydraulic pump. The switching part switches a route of at least one of the pressurized oil and the return oil. The switching part includes an operating portion (for example, an operation knob) and an axis portion (for example, a spool) that advances or retreats when the operating portion is turned. When the operating portion is turned, the axis portion advances or retreats in a direction orthogonal to a direction of turning the operating portion, whereby the route of the oil passage is switched.

Abstract: A hydraulic steering arrangement (2) is described having a main flow path (8) with a flow meter (9) and an amplification flow path (10) opening into the main flow path (8) at a connecting point (11) located between the flow meter (9) and a working port arrangement (L, R). Such a steering arrangement should have in a simple way a large flow of the hydraulic fluid to the working port arrangement. To this end pressure increasing means (17) are arranged in the main flow path (8) upstream the connecting point (11).

Abstract: Control valves 100f, 100g, and 100h that reduce flow passage areas of parallel hydraulic fluid lines 41f, 41g, and 41h respectively when operating devices 34a, 34b for traveling are operated, are each disposed in the parallel hydraulic fluid line 41f, 41g, or 41h so that if saturation occurs during combined operations control likely to generate a significant difference in load pressure between any two actuators, the control valve prevents full closing of a pressure compensating valve lower in load pressure and thus prevents a slowdown and stop of the actuator undergoing the lower load pressure, and so that if saturation occurs during combined operations control likely to generate a particularly significant difference in load pressure between any two actuators, the control valve ensures a necessary supply of hydraulic fluid to the actuator higher in load pressure, thereby preventing a slowdown and stop of the actuator higher in load pressure.

Abstract: A control arrangement for use in a hydraulic control system including a control valve having at least two movable elements, such as spools or poppets, that is adapted to control a main flow through the control valve. The control arrangement further includes a control unit. In an embodiment the control arrangement is adapted to control the operation of the control valve in accordance with a first control scheme, monitor an operating parameter of the control system, and control the operation of the control valve in accordance with a second control scheme in the event that the value of the operating parameter falls outside of a predetermined range.

Abstract: A hydraulic steering device (1) is described comprising a supply port arrangement having a supply port (P) and a tank port (T), a working port arrangement having two working ports (L, R), a main flow path (14) between the supply port (P) and the working port arrangement, a return flow path (16) between the working port arrangement and the tank port (T), flow meter means (15) being arranged in said main flow path (14), said flow meter means (15) comprising at least two flow meters (27, 28) and a flow meter valve means (30), said flow meter valve means (30) in a first operation mode connecting at least two flow meters (27, 28) in parallel and in a second operation mode making inactive at least one flow meter (27). Such a steering device should be operated comfortable for a driver.

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 hydraulic steering arrangement (1) is provided comprising a static steering unit (2) and an adjustable pressure source (3) connected to a pressure port (4) of said steering unit (2) and having a load sensing port (21). Such a steering unit should enable a fast reaction of the steering unit. To this end said pressure source (3) is a dynamic pressure source having an orifice (Adyn) outputting hydraulic fluid to said load sensing port (21), a load sensing line (22) connecting said load sensing port (21) and a low pressure port (11), a control valve (24) being arranged in said load sensing line (22) between said load sensing port (21) and said low pressure port (11), said control valve (24) being actuated by a control pressure within said steering unit (2) and throttling a flow through said load sensing line (22) depending on said control pressure.

Abstract: A system and a method for operating a hydraulic driven work machine including a hydraulic travel motor having a variable displacement is provided, wherein a flow of hydraulic fluid generated by a hydraulic pump is provided to the travel motor and wherein a control valve is provided for controlling the flow of hydraulic fluid from the hydraulic pump to the travel motor. The hydraulic pump is provided with a hydraulic control depending on a load signal generated by the travel control valve and the travel motor is provided with an electric control according to a desired driving behaviour.

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

Abstract: The invention relates to a pressure medium system, in particular a hydraulic system, having a fluid pump for delivering a drive fluid with a certain delivery flow rate and a certain fluid pressure, and having a control unit which switches the fluid pump on or off in order to set a predefined setpoint value of the fluid pressure, wherein the fluid pump exhibits an inertia-induced overrun when switched off, such that during the overrun of the fluid pump, the fluid pressure still rises while the fluid pump has already been switched off. It is proposed that, during the increase of the fluid pressure to the predefined setpoint value, the control unit switches the fluid pump off before the fluid pressure has reached the predefined setpoint value. The invention also includes a corresponding operating method.

Abstract: A hydraulic circuit for operating a tool is provided that is particularly useful in construction equipment such as an excavator, crane, wheel loader, drilling machine, or others. Furthermore, a control unit and a method for controlling the hydraulic circuit and construction equipment including such a hydraulic circuit is disclosed.

Abstract: An actuator assembly is provided. The actuator assembly includes housing configured for operable engagement by a user, a trigger assembly operably supported on the housing, a gas cartridge releasably secured to the housing, a valve assembly mounted within the housing for controlling the flow of pressurized gas through the housing and a cylinder actuator operably operably connected to the valve assembly. The cylinder actuator includes a piston selectively extendable therefrom configured for depressing a plunger. The piston includes a head having an inlet surface disposed within an inlet chamber of the cylinder actuator and an outlet surface disposed within the outlet chamber of the cylinder actuator. The exposed surface area of the first surface is equal to the exposed surface of the second surface.

Abstract: A hydraulic driving device for a working machine surely prevents behavior of a single rod double acting cylinder not intended by an operator when discharge pressure of a main pump is raised to raise exhaust gas temperature to temperature required for burning particulate matter. A selector valve 160 interposed between a spool valve 61 and a rod chamber of a single rod double acting cylinder 51 and a section (a filter regeneration time actuation valve 122, a vehicle body controller 150) controlling the selector valve, are provided. A switch control section prevents a flow of oil directed from the rod chamber of the cylinder toward the spool valve by actuating the selector valve by a poppet of the selector valve when a by-pass cut valve 110 is controlled to increase a load of an engine 21 to a degree exhaust gas temperature reaches temperature required for burning particulate matter.

Abstract: A system for controlling motion of a hydraulic actuator on a refuse collection vehicle. The system includes an operator input device configured to produce a proportional electrical signal that is proportional to the degree of motion of the operator input device. The system further includes a proportional pneumatic control valve that is configured to produce a pressurized air control signal in proportion to the proportional electrical signal, and a hydraulic control valve that is configured to selectively control flow of hydraulic fluid to a hydraulic actuator in response to the pressurized air control signal.

Abstract: A speed of a hydraulic actuator is matched with that of an electric actuator when the hydraulic actuator and the electric actuator are concurrently actuated. When determination units (71, 72) determine that a boom hydraulic cylinder (31) and a rotation generator motor (11) are concurrently actuated based on a controlled variable of a boom control lever (41) and a controlled variable of a rotation control lever (42), a torque of the rotation generator motor (11) is restricted based on a pump discharge pressure (Pp). Therefore, for example, a torque limit command is generated and output such that a torque limit value (TL2) of the rotation generator motor (11) is decreased with a decrease in discharge pressure (Pp) of a hydraulic pump (3).

Abstract: A method for controlling an actuating device in an automated shifting system of a motor vehicle. The position of the actuating device is determined by a path measurement system. The actuating device can be controlled by a pressure regulation device, including a pressure medium reservoir, at least two pressure lines and a switching valve for connecting a first pressure line to a pressure medium line leading to the pressure chamber of the actuating device, and a pressure regulating device for adapting the pressure level of the main pressure line to the control pressure level of the actuating device. By appropriately controlling the pressure regulation device before the piston of the actuating device moves in the intended direction, it is moved in the direction opposite to the intended movement direction. When this movement direction is registered the movement direction is changed to the intended movement direction.

Abstract: Disclosed is a hydraulic system for supplying primary and auxiliary pressure medium consumers with different system pressures, which exceed the load pressure by a pre-determined control pressure differential. Primary load pressure is used to produce a first control pressure differential for operating a primary pressure medium consumer. Auxiliary load pressure is converted in an amplifying device to produce a second, higher control pressure differential for operating an auxiliary pressure medium consumer.

Abstract: A system for controlling motion of a hydraulic actuator during a portion of its range of motion is described, including a sensor on the hydraulic actuator for providing a signal indicating that the actuator is near a portion of its range of motion, and a pneumatic control valve that is configured to selectively modify a pressurized air control signal to in turn restrict flow of pressurized hydraulic fluid to the hydraulic actuator. The hydraulic actuator control system further includes an electronic controller for controlling the pneumatic control valve in response to a signal from the sensor. The hydraulic actuator control system thereby slows the motion of the hydraulic actuator near the portion of its range of motion.

Abstract: A hydraulic drive system is provided with a generator 8 for outputting electricity corresponding to a rotation speed of an engine 7, an electric motor 11 drivable responsive to the electricity from the generator 8, hydraulic pumps 12a, 12b drivable by the electric motor 11, truck-body elevating cylinders 6 for pivoting a truck body 5 in an up-and-down direction, and a stroke detector 14 for detecting a stroke of the control apparatus of the truck-body elevating cylinders 6, and is also provided with a controller 19 for performing control of engine rotation speed. The controller 19 includes a motor electric-power computing means 19a for determining electric power for the electric motor 11, which corresponds to the stroke detected by the stroke detector 14, and a discrimination means 19b for discriminating whether or not the electricity from the generator 8 has become greater than the thus-determined electric power for the electric motor 1.

Abstract: A method for operating a working machine provided with a power source providing power and a plurality of power consuming systems connected to the power source includes the steps of providing a model predicting a power demanded by at least one of the power consuming systems, detecting at least one operational parameter indicative of a power demand, using the detected operational parameter in the prediction model, and balancing a provided power to the demanded power according to the prediction model.

Abstract: In a hybrid excavator, a hydraulic pump and a generator motor are connected in parallel to an output shaft of an engine and a rotation motor is driven by a battery. The generator motor assists the engine by performing a motor function. Power consumption of each of the hydraulic pump and the rotation motor is detected. The output of the hydraulic pump and the rotation motor is controlled such that the sum of the detected power consumption does not exceed maximum supply power set as the sum of power that can be supplied to the hydraulic pump and the rotation motor.

Abstract: A motor control device for construction machinery includes a hydraulic pump; a hydraulic motor driven by pressure oil from the hydraulic pump; a control valve that controls a flow of the pressure oil from the hydraulic pump to the hydraulic motor; a pair of main conduit lines that connect the hydraulic motor and the control valve on a delivery side and a return side thereof; an operation member that operates a spool of the control valve to either a neutral position that does not allow the pressure oil for driving from the hydraulic pump to pass through control valve to the hydraulic motor or a non-neutral position that allows the pressure oil for driving to pass through the control valve to the hydraulic motor; a braking pressure generating device that generates braking pressure in the main conduit lines on the return side in a state where the spool of the control valve is positioned in the neutral position as a result of being operated by the operation member, the braking pressure opposing rotation of the hy

Abstract: Disclosed is a hydraulic system for utility vehicles, in particular agricultural tractors, for supplying primary and/or auxiliary pressure medium consumers with pressure medium, comprising a pump, sucking from a pressure medium tank, the pump being controlled as a function of the load pressure of the pressure medium consumers and supplying a pump pressure exceeding the load pressure by a predetermined control pressure differential. The hydraulic system produces a first control pressure differential for operating a primary pressure medium consumer and a second higher control pressure differential for operating an auxiliary pressure medium consumer. The hydraulic system obtains rapid response of an actuated primary pressure medium consumer and prevents, under certain conditions due to thermal expansion, pressure medium from flowing to the pressure and flow controller of the pump and possibly causing unwanted restriction of the pump.

Abstract: A primary object is to provide a hydraulic drive device for a work machine that is capable of optimum control of pump absorption horsepower according to a change of working condition, thereby reducing fuel consumption, and a secondary object is to provide a hydraulic drive device for a work machine that is based on this primary object and capable of restraining variations in the pump absorption horsepower. When working condition identifying unit (41) determines that, for example, a working condition has changed from working condition (a) to (b), engine control system (40a) changes engine output torque characteristic line from engine output torque characteristic line (ELa) to (ELb), and hydraulic pump control system (40b) changes hydraulic pump absorption torque characteristic line from hydraulic pump absorption torque characteristic line (PLa) to (PLb).

Abstract: A head loss element is interposed between the outlet from the pump delivering high pressure fuel and the pipe feeding combustion chamber injectors. A servo-valve for feeding a hydraulic actuator of a variable-geometry component of the engine has an HP admission inlet connected to the outlet from the pump upstream from the head loss element and an LP outlet connected to the feed pipe downstream from the head loss element. Thus, the flow rate taken upstream from the head loss element for driving the actuator is compensated by the flow rate reinjected downstream from the head loss element, thereby avoiding any movement of the variable-geometry component giving rise to a disturbance in the flow rate delivered to the injectors.

Abstract: A hydraulic operation controlling unit where the engine can be driven stably at a target output torque point and reduction in the work speed can be prevented at the time of light load, includes an engine control unit controlling the output of an engine, so that the output properties of the engine become equi-horsepower properties or approximately equi-horsepower properties in a predetermined engine speed range (N2 to N6) that includes engine speed N3, which corresponds to a matching point M3. A controlling unit increases or reduces the absorbing torque of a hydraulic pump in response to an increase or decrease in the engine speed, and thus, controls the absorbing torque of the hydraulic pump so as to make the output torque T3 of the engine, which corresponds to matching point M3, and the absorbing torque of the hydraulic pump coincide with each other.

Abstract: A return to neutral mechanism includes a hub, a lever and a biasing member. The hub is configured to connect fast to a control rod of an associated hydraulic pump. The lever connects to the hub and includes a location configured to connect to an associated linkage that is connected to an associated steering mechanism. The biasing member connects to the lever for biasing the lever and the control rod toward a neutral position.

Abstract: A hydraulic drive control device which is capable of translating the effect of oil pressure loss reduction into the effect of fuel consumption reduction that is very real to the user. The hydraulic drive control device has (i) a driving hydraulic circuit for driving a hydraulic actuator by supplying pressure oil to or draining it from the hydraulic actuator through control valves, the pressure oil being discharged from a hydraulic pump driven by an engine and (ii) a quick return circuit for directly flowing part of hydraulic oil discharged from the hydraulic actuator back to a tank, while the hydraulic actuator being driven. The hydraulic drive control device also includes an engine controller for controlling the output of the engine such that the output of the engine is restricted when the quick return circuit is opened.

Abstract: A hydrostatic stepless transmission comprises a variable displacement hydraulic pump and a hydraulic servomechanism. The hydraulic servomechanism includes a cylinder chamber, a piston, a slidable member, a pair of pressure reception chambers, and positioning means. The piston is slidably fitted in the cylinder chamber. The slidable member is disposed in the piston so as to constitute a swash plate angle control valve for the hydraulic pump. The pair of pressure reception chambers are formed in the cylinder chamber on the opposite sides of the piston in the slide direction of the piston. By changing a position of the slidable member relative to the piston, one of the opposite pressure reception chambers is supplied with pressure fluid so as to slide the piston and to tilt a movable swash plate of the hydraulic pump connected to the piston, thereby changing a displacement of the hydraulic pump. The positioning means is disposed in at least one of the pressure reception chambers.

Abstract: A hydrostatic stepless transmission comprises: a hydraulic pump; a hydraulic motor, wherein at least one of the hydraulic pump and motor is variable in displacement, and is provided with a movable swash plate; a closed circuit connecting the hydraulic pump and motor to each other through a pair of main fluid passages, wherein one main fluid passage is higher-pressurized during forward traveling, and wherein the other main fluid passage is higher-pressurized during backward traveling; a hydraulic servomechanism for controlling a tilt angle of the movable swash plate of the at least one of the hydraulic pump and motor; a speed-controlling motive member attached to the hydraulic servomechanism, wherein the speed-controlling motive member interlocks with the movable swash plate and is moved by operating a speed control operation lever; and a load controlling system attached to the hydraulic servomechanism.

Abstract: A hydrostatic transmission on a tractor is operated by a microcontroller providing current commands to the hydrostatic transmission pump, and manual controls that provide signals to the microcontroller so the current commands cause the hydrostatic transmission to operate in either a first mode or a second mode. In the first or automatic mode the swash plate position may be continuously variable based on the position of a foot pedal. In the second or gear mode the swash plate may be moved to any of a plurality of discrete positions based on the position of a manually operable switch.

Abstract: A hydraulic system for a work machine having a linkage system is disclosed. The hydraulic system has a tank configured to hold a supply of fluid and at least one hydraulic actuator associated with the linkage system to affect movement of the linkage system. The at least one hydraulic actuator has a first pressure chamber and a second pressure chamber. The hydraulic system also has an independent metering valve associated with the first pressure chamber. The independent metering valve has a valve element movable between a first position at which fluid communication between the first pressure chamber and the tank is blocked, and a second position at which fluid is allowed to drain from the first pressure chamber to the tank. The hydraulic system further has at least one sensor configured to sense a parameter indicative of a pressure in the second pressure chamber, and a controller in communication with the independent metering valve and the sensor.

Abstract: A hydrostatic stepless transmission comprises a hydraulic pump and a hydraulic motor, at least one of the hydraulic pump and motor being variable in displacement; a closed circuit for fluidly connecting the hydraulic pump and motor to each other therethrough, the closed circuit including a pair of oil passages between the hydraulic pump and motor, one of the oil passages being hydraulically higher-pressured and the other being hydraulically depressed when the hydraulic pump delivers oil to the hydraulic motor; a speed change operation device for changing output rotational speed of the hydraulic motor; and a leak valve connected to the speed change operation device.

Abstract: A hydrostatic vehicle driving system structured from an engine to a drive axle in a working vehicle. A hydraulic pump driven by the engine and a variable displacement hydraulic motor for driving the drive axle are fluidly connected with each other through a hydraulic circuit. A motor capacity control system controls capacity of the hydraulic motor in correspondence to the condition of load on the engine. The motor capacity control system comprises load-detection means detecting hydraulic pressure in the hydraulic circuit replacing the load on the engine, a hydraulic actuator for changing the capacity of the hydraulic motor, and actuator-control means controlling the hydraulic actuator according to the detection of hydraulic pressure by the load-detection means.

Abstract: For a power assisted steering system for vehicles, in particular passenger cars, there is provided a hydraulic circuit with a servopump, a three-way flow regulator valve which is located at the junction between the pump and a servoactuator and has a measuring throttle, located in the inflow to the servoactuator, as a fixed throttle and an outflow throttle which is located in a bypass of the latter and which determines a variable throttle cross section by means of a piston which is charged alternately as a pressure compensator. The piston, which is charged via an active actuator element, changes the outflow throttle cross section as a function of the current applied in order to change the volume flow which passes via the measuring throttle.

Abstract: A method is provided for controlling hydraulic flow to a hydraulic actuator in fluid communication with a pump. The method includes generating a signal representative of a speed of the pump and selecting a relationship from a plurality of relationships between valve commands and an operator input. The selection is based upon the speed signal. A valve is modulated to control the hydraulic flow to the hydraulic actuator based on the selected relationship and the operator input.

Abstract: A hydrostatic stepless transmission comprises a hydraulic pump and a hydraulic motor, at least one of the hydraulic pump and motor being variable in displacement; a closed circuit for fluidly connecting the hydraulic pump and motor to each other therethrough, the closed circuit including a pair of oil passages between the hydraulic pump and motor, one of the oil passages being hydraulically higher-pressured and the other being hydraulically depressed when the hydraulic pump delivers oil to the hydraulic motor; a speed change operation device for changing output rotational speed of the hydraulic motor; and a leak valve connected to the speed change operation device.

Abstract: A hydrostatic vehicle driving system structured from an engine to a drive axle in a working vehicle. A hydraulic pump driven by the engine and a variable displacement hydraulic motor for driving the drive axle are fluidly connected with each other through a hydraulic circuit. A motor capacity control system controls capacity of the hydraulic motor in correspondence to the condition of load on the engine. The motor capacity control system comprises load-detection means detecting hydraulic pressure in the hydraulic circuit replacing the load on the engine, a hydraulic actuator for changing the capacity of the hydraulic motor, and actuator-control means controlling the hydraulic actuator according to the detection of hydraulic pressure by the load-detection means.

Abstract: A system and method for controlling an electro-hydraulic valve arrangement to perform a pump check function are provided. The system includes an electro-hydraulic valve arrangement disposed between a source of pressurized fluid and a hydraulic actuator. Pressure sensors are provided to sense a source pressure representative of the fluid pressure between the source of pressurized fluid and the electro-hydraulic valve arrangement and an actuator pressure representative of the fluid pressure between the electro-hydraulic valve arrangement and the actuator. A control device receives a signal to open the electro-hydraulic valve arrangement to provide a requested flow rate to the hydraulic actuator. The received signal is modified to prevent fluid flow through the electro-hydraulic valve arrangement when the source pressure is less than the actuator pressure.

Abstract: A fluid-operated circuit for setting the top dead center and the bottom dead center of the punch actuation cylinder in punching machines comprises a first copying distributor which distributes pressurized fluid, which has a spool at one end and can be connected in output to the upper section of the chamber in which the actuation cylinder slides and in input to a first pump for feeding low-pressure fluid and to at least one first fast-acting electric valve element; the spool can be pushed into position by contact by a corresponding setting element with continuous micrometric movement.

Abstract: A hydraulic control system having a pump for delivering fluid under pressure from a fluid reservoir, a hydraulic actuator selectively driven by the fluid, the system comprises a main flow control valve connected between the pump and the actuator for selectively providing the fluid to and from the actuator, and a control unit connected to the main flow control valve for controlling operation of the main flow control valve to control the rate of change of the area of the main flow control valve relative to the delivery of fluid from the pump, and the control unit connected to the pump to increase or decrease the actual pump command proportional to the inverse of the pump command.

Abstract: An electro-hydraulic transducing valve (3a) and other elements associated with cylinder-controlling components, such as a control valve (3), are connected to the output end of a controller (23) adapted to perform control computation based on electric manipulation signals send from and electric joy stick (12a) or the like. Control valve return pressure (PT) and load-sensing pressure (PL) are detected by the first and second detectors (18), (19) so that start-up of a hydraulic cylinder (7) or the like is detected based on rise of the differential pressure (&Dgr;P) between the two types of pressures. The controller (23) is provided with a function generating unit (14a) and a calibration computing unit (20). The function generating unit (14a) has a reference function (F) that determines the relationship between electric manipulation signals and command values for commanding the electro-hydraulic transducing valve (3a) and other similar elements.

Abstract: A hydraulic system for a forklift includes a handle angle sensor for outputting a rotational angle signal indicative of a rotational angle of a handle, a wheel angle sensor for outputting a wheel angle signal indicative of a steering angle of wheels, and a controller. The controller calculates a rotation angular velocity of the handle based on the rotational angle signal from the handle angle sensor to discharge from the hydraulic pump the hydraulic fluid of a flow rate in conformity with this rotation angular velocity, and controls the flow rate of the hydraulic fluid supplied to the power steering cylinder based on the rotational angle signal from the handle angle sensor and the wheel angle signal from the wheel angle sensor to steer the wheels in conformity with the rotational angle of the handle.

Abstract: A pneumatic control assembly for controlling a hydraulic power device includes a power control rod and at least one direction control rod. The power control is movable between an engaged position and a disengaged position to activate/de-activate a hydraulic fluid supply source for supply of hydraulic fluid to the hydraulic power device. The direction control rod is movable among a forward position, a neutral position, and a backward position wherein the forward position corresponds to driving the hydraulic power device in an working stroke to work, the backward position corresponds to moving the hydraulic power device in a returning stroke and the neutral position is between the forward position and backward position and corresponding to having the hydraulic power device maintained stationary. A peg is provided on the power control rod.

Abstract: A hydraulic source(20) comprises a hydraulic pump(62) driven by a motor(61), which operates based on the power and control data from a non-contact power feeding apparatus(30); a hydraulic tank(63); a solenoid valve(64); a relief valve(65); a hydraulic pressure gauge(66); a pilot check valve(67) for clamping and a pilot check valve(68) for unlocking that are interposed between the solenoid valve(64) and hydraulic cylinders(41a to 41d); a pressure switch(69) for clamping which is inserted into a piping for connecting the pilot valve(67) and the hydraulic cylinders(41a to 41d); and an pressure switch(70) for unclamping which is inserted into a piping for connecting the pilot check valve(68) and the hydraudic cylinders(41a to 41d). This hydraulic source is combined with a hydraulic machine for applications where jig or jigs move freely to promote automation of machining, assembly and inspection of workpieces on a moving body.

Abstract: A hydraulic control valve has a two position body shifted by rotation. The shaft of the valve body carries a drive wheel segment extending through an arc that corresponds to the shift angle of the valve. A spring is provided to bias, at least in the final stage of rotation in either direction, the wheel segment in the opposite direction of rotation. This enables the valve body to be positioned into the other position in a reliable manner.

Abstract: In a drive unit which includes an electric motor and a cooling fan as well as a hydraulic power steering pump to be driven by the electric motor, the cooling fan is operatively connected to the motor by a clutch and a control circuit is provided for operating the clutch so as to disengage the cooling fan whenever the power steering unit needs hydraulic fluid for steering assistance, whereby both, the cooling fan and the hydraulic pump, are never operated at the same time so that the motor may be relatively small, light and inexpensive.

Abstract: In order to achieve a gear ratio control of a continuously variable transmission, a transmission gear ratio is controlled based on a difference between an actual engine speed and a target engine speed to be set in response to a first parameter corresponding to an accelerator opening. When controlling the transmission gear ratio, a plurality of change characteristics of the transmission gear ratio are set for, in particular, the kickdown gear shifting. In response to a second parameter representing the driver's demand for a traveling condition, a change characteristic of the transmission gear ratio is selected from among the plurality of change characteristics of the transmission gear ratio, to execute the speed ratio control in accordance with the thus selected change characteristic of the transmission gear ratio when a kickdown gear shifting is needed.

Abstract: This invention has for its aim to provide a hydraulic circuit system arranged such that, even at the time of commencement of drive of a hydraulic actuator with a large inertia, a slow rise in the drive pressure can be achieved, thereby preventing the occurrence of hunting phenomenon. The hydraulic circuit system according to the present invention comprises a plurality of operating valves (15) provided in a discharge conduit (10a) of a hydraulic pump (10), and pressure compensating valves (18) provided in connection conduits between these operating valves (15) and respective hydraulic actuators (16), wherein each of the pressure compensating valves (18) is set at a highest value of load pressures of each of the hydraulic actuators (16), and the displacement of the pump is controlled by a change-over valve (14) adapted to be actuated by the difference between the pump discharge pressure and the load pressure.

Abstract: Electrically operated hydraulic pump systems are commonly used on tailgate loaders and small dump truck hoists. The systems include a switch which, when closed, couples the vehicle battery to the pump driving motor and a hydraulic lowering valve which, when opened, drains the output port of the pump to a reservoir. The control system for this electric pump system comprises an air cylinder operatively connected to the switch and a second cylinder operatively connected to the hydraulic lowering valve. A switching valve is connected between each air cylinder and a source of air pressure. The switching valves may be operated by an operator to pump or drain hydraulic fluid.