Abstract: A micropump according to the invention uses axially oriented pistons to define a pump volume. Translating the pistons axially with respect to each other within a pump housing draws a metered amount of fluid into the pump volume from a reservoir port for delivery to a cannula port when the space is collapsed. Radially situated seals on the pistons cooperate with the axial movement to close off and open the cannula port and the reservoir port respectively at different positions of the piston stroke.

Abstract: At least one choked flow passage communicates between one side of the movable member and the other side of the movable member and limits an amount of fuel, which passes from the one side of the movable member to the other side of the movable member, when the movable member is moved by an urging force of a relief spring toward a valve element. A larger amount of fuel, which is larger than the amount of fuel that is passable through the at least one choked flow passage, flows from a first return flow passage to a second return flow passage, when the movable member is moved toward the other side, which is opposite from the valve element, against the urging force of the relief spring.

Abstract: A fluid pumping device having a pump housing containing a piston chamber and a reciprocating piston, an inlet port and an outlet port allowing a fluid to enter the piston chamber during an instroke of the piston and be expelled during an outstroke. The device further having a valve switching element movably mounted against a valve base member, with a piston chamber aperture connected to the piston chamber and an inlet aperture and an outlet aperture connected respectively to the inlet and outlet ports of the fluid pumping device. The element has a grooves in the valve base member providing, a first communication between the inlet aperture and the piston chamber aperture so that fluid is sucked, into the piston chamber during part of the piston instroke, and a second communication aperture expelling fluid out of the piston chamber, through the outlet port during part of the piston outstroke.

Abstract: Disclosed is a lifting gear valve arrangement for controlling a double-action lifting gear or an add-on unit with a continuously adjustable directional control valve and with an individual pressure compensator via which a pressure medium volume flow to and from a lifting cylinder of the lifting gear can be controlled. A proportionally adjustable pressure limiting valve is provided in the pressure medium flow path between an outlet connection of the directional control valve and a working connection of the lifting gear valve arrangement, via which the pressure inside this area can be limited to a maximum value. The adjustment of the pressure limiting valve is preferably performed as a function of the operating states of the lifting gear or of the type of add-on unit.

Abstract: A holding control valve of the present invention is configured such that: a spool is configured to perform strokes by a piston configured to operate by introduction of pilot pressure and have a larger diameter than the spool; the piston is divided into a pilot piston configured to receive the pilot pressure and a relief operation piston disposed adjacent to the spool to receive pressure of relief oil discharged when a relief valve operates; and the relief oil is introduced to between the pilot piston and the relief operation piston.

Abstract: A system operates a hydraulic actuator, such as a cylinder, in one of several modes that include powered extension and retraction, self-powering regeneration modes in which fluid exhausting from one cylinder chamber is routed into the other cylinder chamber, and cross function regeneration modes wherein the fluid exhausted from one actuator is routed in the supply conduit to power a different actuator. A controller determines which modes are viable based on existing system conditions and selects from among the viable available modes. That determination is a function of the desired velocity for the actuator, the hydraulic load on the actuator, and pressures in the supply and return hydraulic conduits. The system also can recover potential or kinetic energy through pressure intensification which recovered energy can be used to power another simultaneously active hydraulic function or to drive the prime mover via an over-center variable pump/motor.

Abstract: The invention concerns a hydraulic valve arrangement (1) with a supply connection arrangement comprising a high-pressure connection (P) and a low-pressure connection (T), a working connection arrangement comprising two working connections (A, B), which can be connected to a motor (4), a directional valve arrangement (5) located between the supply connection arrangement (P, T) and the working connection arrangement (A, B), and a compensation valve (15) acted upon in a first activation direction by a pressure in a first pressure chamber (33), which is connected to a load-sensing pipe (LS), and, if required, by a spring (32), and in a second activation direction opposite to the first activation direction by a pressure downstream of the directional valve arrangement (5), said pressure acting in a second pressure chamber (34), the compensation valve (15) having an inlet (14) and an outlet (19).

Abstract: The invention relates to hydraulic control in a hydraulic system for the operation of a machine tool such as a press for processing material of a certain type, especially for the operation of the scrap cutters. Said control allows for impact attenuation and combined rapid motion switching with load compensation and transfer of a hydraulic medium of a hydraulic cylinder for the movement of the other. According to the invention, said control comprises hydraulic media of a hydraulic cylinder for pre-control of a first main valve element (2.4.0), a second main valve element (2.7.0) and a third main valve element (3.7.0) which are functionally combined and a fourth valve (2.5).

Abstract: A method for controlling an air servo cylinder apparatus includes an advancing process of advancing a piston up to a target position by controlling, by a controller, servo valves individually connected to a pressure chamber on the head side and that on the rod side of the cylinder, and a pressurizing process of subsequently applying a required pressurizing force to the piston. In the advancing process, the piston starts to be driven with the servo valve on the head side opened to the air intake side and the servo valve on the rod side opened to the exhaust side. Thereafter, the opening degree of the servo valve on the rod side is varied into an opening degree in accordance with a deviation of the current position from the target position, and thereby the piston is smoothly decelerated as it approaches the target position.

Abstract: A control device for a working device (12) connected to a hydraulic circuit (10), especially for a load fork (16) which can be raised and lowered with a working cylinder (14) in a fork-lift truck. A valve control unit moves into an adjustment position when the load fork (16) is lowered even when carrying a load (18). A predefinable maximum volume flow is maintained in the hydraulic circuit (10). By providing the valve control unit with a pressure regulator (26) limiting a pilot control pressure for the control valve (28), once a predefinable regulating pressure differential is reached in the hydraulic circuit, the control valve moves into a regulating position to maintain the maximum volume flow. The known flow control valve is replaced in the main flow by a pressure regulator (26) disposed in the pilot control circuit (40), and only needs to be dimensioned for low volume flows.

Abstract: A power steering system for a vehicle, comprises a steering shaft connected to a steering mechanism. A hydraulic power cylinder is provided for assisting a steering effort of the steering mechanism. A reversible pump is provided having first and second discharge ports which are respectively connected through first and second hydraulic lines with two hydraulic pressure chambers of the hydraulic power cylinder so that the two hydraulic pressure chambers are respectively provided with hydraulic pressures. A driving device is provided for driving the reversible pump to rightly and reversely rotate. A differential pressure regulating valve is disposed in the hydraulic circuit to maintain pressure at least in the first and second hydraulic lines at a level of atmospheric pressure or higher in an inoperative condition of the reversible pump.

Abstract: A controller for controlling the flow rate of compressed air to a spray paint gun as well as to a comparable tool which is optimally operative dependant upon receiving a specified flow rate of air includes a flow control valve which regulates the air flow rate therethrough based on a pressure differential signal received from an air flow meter. The pressure differential signal transmitted to the air flow controller is balanced against an opposing spring biased needle in the flow controller.

Abstract: The invention relates to a hydraulic control apparatus for a construction machine. The hydraulic control apparatus includes a target velocity table (4) which stores target actuation velocities of a hydraulic actuator (30) corresponding to operation amounts of the operation member (2) to be operated by the operator, a target acceleration table (5) which stores target actuation accelerations of the hydraulic actuator (30) corresponding to operation amounts of the operation member (2), and one of the target velocity table (4) and the target acceleration table (5) can be selected by operation of a selection switch (3) by the operator. Further, by the control means, the target value corresponding to the operation amount of the operation member (2) using the table selected by the selection switch (3), and a control valve (17) for controlling the pressure oil supplying amount from a hydraulic pump (16) to the hydraulic actuator (30) is controlled based on the set target value.

Abstract: In the present invention, sensors for cylinder control are connected to a main cylinder which has an internal cylinder chamber which is partitioned by a piston into two chambers, and they detect the operational state of the piston. There are provided accumulators connected to one of said two chambers by connecting conduits and whose interiors are pressurized by hydraulic fluid which is expelled from said one chamber, and also stop signal generation mechanisms which generate signals to stop the driving of said main cylinder by pressure differential between said accumulators and said connecting conduits generated at the instant that increase of pressure from said one chamber stops.

Abstract: A plurality of hydraulic actuators are connected between a supply line and a tank return line. A separate desired velocity is requested for each hydraulic actuator. In response to a respective metering mode and the desired velocity for each hydraulic actuator, the flow requirements that each hydraulic actuator has from the supply and return lines are derived. A determination is made as to what fractions of the required flows can be provided by the flow levels that are available from the supply and return lines. Those fractions are used to convert the desired velocity for the given hydraulic actuator into a velocity command which indicates the velocity of the given hydraulic actuator that can be achieved with the available fluid flows. The respective velocity command is used to control the flow of fluid to each hydraulic actuator.

Abstract: An actuator is part of a hydraulic circuit branch that has a first electrohydraulic proportional valve connecting the actuator to a supply line containing pressurized fluid and a second electrohydraulic proportional valve connecting the actuator to a tank return line. A method for operating the valves includes requesting a desired velocity for the hydraulic actuator and sensing a parameter which varies with changes of a force on the actuator. The desired velocity and the parameter are used to derive an equivalent flow coefficient which characterizes fluid flow in the hydraulic circuit. From the equivalent flow coefficient, first and second valve flow coefficient are derived and then employed to activate each of the first and second electrohydraulic proportional valves. The coefficients may characterize either conductance or restriction in the respective part of the hydraulic system.

Abstract: The present invention provides a speed governor (5) suitable for use in a fluid driven down-hole tool (3). The speed governor comprises an actuator (7) operatively coupled to a motive fluid flow control valve (6). The actuator is and arranged so as to be activatable, directly or indirectly, in response to the running speed of the tool (3), for opening of the control valve (6) with increasing rotational speed of the motor (3) above a predetermined speed limit thereby to limit the rotational speed of the downhole tool (3).

Abstract: A controller for controlling the flow rate of compressed air to a spray paint gun as well as to a comparable tool which is optimally operative dependant upon receiving a specified flow rate of air includes a flow control valve which regulates the air flow rate therethrough based on a pressure differential signal received from an air flow meter. The pressure differential signal transmitted to the air flow controller is balanced against an opposing spring biased needle in the flow controller.

Abstract: A method and system for controlling the steady-state speed of a cylinder in an electrohydraulic system having multiple cylinders includes a plurality of levers for controlling each of the cylinders. A controller, in communication with the levers and the hydraulic cylinders, has a limited number of parameters defining at least one desired relationship between steady-state speed and lever position for each of the cylinders stored therein. The controller further determines a current desired relationship for each of the cylinders from the associated at least one desired relationships. Upon detecting movement of the lever, the controller determines a current position of the lever associated with one of the cylinders and then controls the steady-state speed of the associated cylinder based on the limited number of parameters defining the current desired relationship and the position of the lever.

Abstract: A protection device for controlling the motion of a pneumatic actuator, having at least one elongated cylinder provided with a piston, dividing the cylinder into a first chamber and a second chamber, an actuating pressure supply line connectable to at least one of the first and second chambers, a control unit for controlling the motion of the piston relatively to the cylinder, and a motion sensor adapted to sense a piston feature related to the piston motion and co-operating with the control unit. According to the invention, the control unit limits the motion of the piston as soon as signal from the sensor indicates that an excessive value of the piston motion has been established.

Abstract: A damping device for installation in a hydraulic adjustment device such, for example, as for motor vehicle clutches. The hydraulic adjustment device has a cylinder that is either an input cylinder or actuator or an output cylinder. The input cylinder or actuator, which is connected to an operating pedal of the motor vehicle, is also connected to the output cylinder via a hydraulic line filled with fluid. The damping device opposes a throttle resistance to the flow of the fluid in both flow directions. The damping device comprises a disk having first and second spring washers on either side of the disk. The disk has passage openings, which are covered on the respective sides by one of the first and second spring washers. The damping device is installed in the hydraulic adjustment device to suppress disturbing vibrations acts as both a vibration filter and an operating speed limiter. In addition, a constant throttle resistance is maintained relative to the fluid at all ambient temperatures.

Abstract: A control apparatus for an industrial vehicle is disclosed. The vehicle has a rear axle that is swingable during straight travel of the vehicle and can be fixed during turning of the vehicle. A damper looks or unlocks the rear axle. A controller has a memory that stores a first value and a second value of an angular velocity rate that represents an angular velocity per unit time. The controller activates or deactivates the damper. The controller activates the damper to lock the rear axle when the angular velocity rate is greater than the first value. The controller deactivates the damper to unlock the rear axle when the angular velocity rate is kept smaller than the second value for a predetermined time period after the angular velocity rate has become smaller than the second value.

Abstract: An oil-pressure cylinder in a crushing device is connected to a crushing jaw via a pivot shaft so that the crushing jaw can open and close. The extension of oil-pressure cylinder causes the crushing jaw to close and crush the object to be crushed. Oil-pressure cylinder has a piston with a greater pressure-receiving area on the head side than on the rod side. An acceleration valve serves to switch the extension/retraction operations of the oil-pressure cylinder. During a rod unloaded interval, beginning when the crushing jaw starts to close and ending when the crushing jaw comes into contact with the object to be crushed, the acceleration valve makes communication between a head-side port and a rod-side port in the cylinder continuous, while the oil path from the rod side to a tank is blocked. The oil from the rod side is made to flow to the head side.

Abstract: In order to improve speed controllability both in low and high speeds, thereby stabilizing the speed of a hydraulic cylinder, both the flow-in amount of hydraulic operating fluid flowing from a hydraulic source to the hydraulic cylinder having a run-around circuit and the flow-in amount of hydraulic operating fluid flowing from the run-around circuit to the hydraulic cylinder are controlled simultaneously by a control valve, so that the speed of the hydraulic cylinder is controlled.

Abstract: An apparatus for controllably moving an implement is provided. The implement is connected to a work machine and is movable between first and second implement positions in response to operation of a hydraulic actuator. The apparatus includes a joystick with first and second positions and a neutral position. The joystick is normally biased in a neutral position and is movable between the first and second positions. The apparatus senses the position of the joystick and responsively generates a joystick position signal. The joystick maintained at the first and second detent positions in response to manual movement of the joystick to the respective first and second detent positions. The joystick is released from the detent position in response to receiving a release detent signal. The apparatus senses the position of the work implement with respect to the work machine. The apparatus provides hydraulic fluid flow to the hydraulic actuator in response to a magnitude of an electrical valve signal.

Abstract: A method for controlling an apparatus (100) for controllably moving an implement (102) is provided. The implement (102) is connected to a work machine (104) and is movable between first and second implement positions in response to operation of a hydraulic actuator (106). The apparatus (100) includes a joystick (306) with first and second positions and a neutral position. The joystick (306) is normally biased in a neutral position and is movable between the first and second positions. The apparatus senses the position of the joystick (306) and responsively generates a joystick position signal. The joystick (306) maintained at the first and second detent positions in response to manual movement of the joystick to the respective first and second detent positions. The joystick (306) is released from the detent position in response to receiving a release detent signal. The apparatus (100) senses the position of the work implement (102) with respect to the work machine (104).

Abstract: The hydraulic circuit directional control valve 20 is provided in a line connected with a lower chamber 13 of the hydraulic cylinder 1 and the B-port of the servo valve 3. A check valve 22 permitting oil flowing into the P-port of the servo valve 3 from the lower chamber 13 is provided in the line in parallel with the hydraulic circuit directional control valve 20 and connected with the lower chamber 13 and the P-port of the servo valve 3. When making the ram 15 move downward with high speed, the hydraulic differential circuit is constituted by changing the hydraulic circuit directional control valve 20 such that the delivery oil exhausted from the lower chamber 13 returns to the P-port of the servo valve 3. The hydraulic oil supplied from the hydraulic pump 1 flows into the upper chamber 12 through the servo valve 3. The delivery oil exhausted from the lower chamber 13 returns to the suction side of the P-port of the servo valve 3 through the check valve 22, assisting the flow rate of the hydraulic pump 2.

Abstract: An electrohydraulic governing system for governing system for governing at least movements of objects (3, 4) actuated by pressure fluid, one at the time or several simultaneously, which can receive or deliver energy, wherein the governing desires from an impulse generating guide means (1) via an electronic guide unit (2) are performed provided that this is possible in view of limitations in a pressure fluid source (5) delivering pressure fluid to the objects or provided this can be allowed in view of the strength, life and stability of the machine governed by the guide system or by the objects and as long as the functions operate and as long as the guide system or the guided machine is governed within limited secure field, wherein all the time the volume of the different parts or the sytem filled with pressure medium is measured directly or indirectly and upon governing of the pressure medium source and the valve means (8, 13, 15) connected to respective object it is governed so that the pressure fluid source

Abstract: A hydraulic control system for controlling the motion of a double acting hydraulic actuator determines the flow to and from the actuator in accordance with1. the desired movement of the actuator2. the measured hydraulic pressures on opposite sides of the piston of the actuator3. a selected, predefined model of the system of which the actuator forms a partand sets the valves controlling the flows accordingly.

Abstract: Vehicles having implements are typically used to perform repetitive functions in work cycles. An implement control system raises and lowers an implement relative to the vehicle and reduces the stresses applied to the vehicle from abruptly stopping the motion of the implement. A lever pilot signal is produced in response to the pivotal position of a control lever. An electrohydraulic pilot signal is also produced. The pilot signal having the greater pressure is directed to a main valve for controlling the position of the implement. The method and apparatus of the instant invention are applicable to a number of vehicles having a hydraulically operated implement.

Abstract: A distributor for hydraulic cylinders (2), especially applicable to crane drive cylinders, which comprises an axial sliding runner (4) for selection of the oil circuit. Said runner (4) is hollow, forming two separate chambers (19,20) adjacent to the cylinder chamber supply and return ducts with which it is connected through holes in the wall of the said runner. One of the chambers (19) includes means for varying the degree to which the holes are opened, according to the return oil pressure from the cylinder withdrawal chamber. The other chamber (20) incorporates means for opening or closing the connection through it, according to the pressure being delivered by the pump, to the cylinder withdrawal chamber oil supply duct. Thus it is possible to regulate the flow as an inverse function of the load and to reduce the effect of induced pressure.

Abstract: A double-acting accelerated forging hammer and method of operation are disclosed. The hammer is of the type having a vertically oriented cylinder, a piston slidably mounted within the cylinder having a downwardly depending piston rod extending along the cylinder and attached to a hammer. A gas accumulator communicates with the cylinder above the piston for supplying gas under pressure thereto during a forging stroke, and a fluid accumulator communicating with the cylinder below the piston for supplying fluid thereto at a higher pressure than the gas to dirve the piston upwardly during a return stroke. A fluid tank supplies fluid to recharge the accumulator and receives fluid from the cylinder during the forging stroke. Variable valves control the rate of fluid flow from the cylinder and thereby control the rate at which the piston descends within the cylinder.

Abstract: A digitally controlled air-over-hydraulic actuator includes a pneumatic cylinder and a hydraulic cylinder each having a separate piston and a common connecting rod. The pneumatic piston applies force to the connecting rod urging movement of the hydraulic piston. Bleeding of oil from one side of the hydraulic piston to the other is controlled by means of digital pulses applied to a digital valve that allows oil on either side of the hydraulic piston to flow to the other. The digital valve includes a moving piston having an oil passage that is momentarily aligned with ports to opposite sides of the hydraulic cylinder. A control system senses the differential pressure between opposite sides of the pneumatic piston to produce pulses that accelerate the digital valve piston past the ports, precisely controlling forced movement of the hydraulic piston.

Abstract: A remote handling manipulator having a slave arm and a manually operated controller with a grip mechanism, is provided with a force feedback system to impose a force resisting operation of the grip mechanism related to a load experienced by the slave arm. A jaw mechanism of the slave arm is operated by a pressurized fluid, and in the system the pressure of the fluid and the effort exerted by the grip mechanism are compared to produce an error signal used for regulating the force applied to the grip mechanism.

Abstract: A closed center four-way poppet actuator control device is incorporated into a pneumatic actuation system for controlling the movement of flight surfaces. The closed center four-way poppet actuator control device has a housing, a pair of two-way poppet valves in the housing, a rocker arm assembly mounted on the housing and connected to the pair of two-way poppet valves, and a diaphragm assembly also mounted in the housing and in contact with the two-way valves. A torque motor-driver assembly connected to the diaphragm assembly actuates the two-way valves as determined by control signals. The rocker arm causes the two-way valves to function oppositely each other: one allows high pressure gas to be input to a lobe motor actuator while the other allows gas to be output from the lobe motor actuator. Each two-way valve has a cylindrical poppet valve for inletting the gas to the actuator and a disk poppet valve for outputting the gas from the actuator to a vent.

Abstract: The invention pertains to tensioners for maintaining a load between two relatively movable structures, such as an offshore drill ship or the like and a riser pipe. First and second tensioner bodies are mounted for relative reciprocation, and are further functionally interconnected with the first and second offshore structures respectively. Relative movement of the offshore structures tends to cause corresponding relative reciprocation of the tensioner bodies. A force is applied between the tensioner bodies tending to reciprocate them in a first directional mode and thereby supporting the offshore riser pipe with respect to the offshore support structure. A balancing chamber cooperative between the tensioner bodies communicates with a source of pressurized fluid for resisting reciprocation of the tensioner bodies in the first directional mode, but includes an outlet for egress of the pressurized fluid to permit such reciprocation under controlled conditions.

Abstract: The invention relates to a hydraulic motor assembly which includes a hydraulic servomotor operable in either direction with a control valve. When the motor is operated in a selected direction, as distinguished from the return direction, it is desired that external forces acting on linkage connected to the piston of the hydraulic motor do not alter the speed of the piston. The control valve has two operating positions and two sets of supply and return passages which facilitate operation of the servomotor in either direction. A brake valve between one of the servomotor ports and the control valve has a scanning port which scans or senses the downstream pressure of either of the control valve supply passages, depending on the control position of the control valve.

Abstract: A safety reverse arrangement is disclosed for reversing the direction of the powered operation of a door upon encountering an obstacle during its opening and closing movement. The arrangement includes a piston fit within a vented cylinder, which is stroked by the opening and closing movement of the door, while a pair of air flow detector switches receive the resulting air outflow developed during stroking of the piston. The air flow detector switches are integrated with a control circuit for the door powering arrangement such that, after an initial short delay period, any interruption in the flow to the flow detector results in a reversing of the direction of the door movement. Such interruption of air flow occurs upon the door encountering an obstacle during its opening or closing movement.

Abstract: This invention relates to power tools and more particularly to an air-operated power tool commonly used for automotive or other assembly operations for installing threaded fasteners. The device of this invention shuts off the power tool as it approaches the stall condition. Motor rotation is sensed by transferring a small mass of air in proportion to the speed of the motor but independent of the air expanded to operate the motor. The air transferred is utilized to create a signal which through an air-operated valve shuts the power tool off when the speed is reduced below a predetermined amount as when the torquing cycle is nearing completion.