Abstract: A hydraulic control system comprising a hydraulic actuator having opposed openings adapted to alternately function as inlets and outlets for moving the element of the actuator in opposite directions, a pump for supplying fluid to said actuator, pilot operated meter-in valve means to which the fluid from the pump is supplied for controlling the direction of movement of the actuator, pilot operated meter-out valve means associated with each opening of the actuator for controlling the flow out of said actuator. The pressure of fluid being supplied to the actuator by the meter-in valve means is sensed and caused to produce a force opposing the movement of the meter-in valve means by the pilot pressure resulting in a smooth and accurate control of the movement of the actuator.

Abstract: Valve trigger assembly for a pneumatic nailer including a geometrically configured valve bushing having threads at a lower end for securing the assembly into a housing of the nailer and a plurality of O-rings about the configured valve bushing. A geometrically configured valve piston including a plurality of O-rings about the configured valve piston reciprocates in the valve bushing against a spring and is retained in the valve bushing by a snap ring. Small holes in a mid-portion of the valve bushing provide for passage of air supply line pressure for charging the poppet through the valve bushing and large holes in an upper portion of the valve bushing. The large holes also provide for discharge of air behind the poppet and through the valve bushing to the atmosphere.

Abstract: Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor means cooperating with vent openings to vary venting and thereby vary fluid pressures in the fluid passages.Fluid conduits connect these pressure outputs to a double acting piston moving in a cylinder whose opposite ends are connected to the fluid conduits. The piston and cylinder form the responder of the system.A receiver is formed by a piston and cylinder or other fluidic motor remotely fluidically connected to the responder, the motor driving a load.A feedback means controlled by the position of the responder piston and/or the load varies pressure in the fluid conduits by variably venting same.Both rotary and linear types of transmitters and load feedback means and receivers may be used.

Abstract: A hydraulic operating apparatus including an actuating cylinder having a piston arranged therein and moved by a fluid under high pressure further includes a control valve having only one metallic seal whether the piston is at its upper or lower positions. The control valve is operative to apply the fluid under high pressure to a pressure receiving surface of the piston on the opposite side of a piston rod to move the piston in a direction in which the piston rod extends from the piston and to discharge the fluid existent on the opposite side of the piston rod from the actuating cylinder to move the piston in a direction opposite the direction in which the piston rod extends from the piston.

Abstract: A mechanism (80) is provided to controllably lower an actuator (28) upon the loss of a source (62) of pilot fluid in a fluid system requiring a float condition of operation. A resolver (80) is located in a vent line of a make-up valve and is connected to a second load supporting end (32) of the actuator (28) and is controllably vented to a tank (38) by moving a pilot control valve (48) to a fourth position (D). This eliminates the need to provide complicated systems having pilot operated check valves which are more difficult to control.

Abstract: The invention relates to a hydraulic blocking valve, a so-called holding valve (10), the shutting-off member of which consists of a movable ball (16) coacting with a seat (17) in an inlet chamber (24). The space (15) on the side of the ball opposite its seat forms an operating chamber (15), and both chambers are joined by a constriction passage (13) counteracting flow of hydraulic liquid between the chambers. The operating chamber (15) is in communication with valve means (32) by the aid of which the pressure in the operating chamber can be heavily reduced, e.g. by being taken to a tank (44), resulting in that the ball (16) is thrust from its seat (17) to open the valve. A throttling means (25, 26) simultaneously comes into action for reducing the flow, i.e. liquid loss through the valve means (32) from the operating chamber (15). When the valve means is subsequently closed, pressure is once again built up against the ball so that the latter is pushed towards its seat (17) for closing the valve (10).

Abstract: Pump pressure in a fluid power assisted steering device is regulated through the suction side of the pump to supply pressurized fluid to a servomotor through a fluid pressure actuated steering control valve. A pre-control valve controls pressure in an actuating chamber of the steering control valve in response to displacement of the hand steering wheel to obtain a variation in servomotor pressure that is a linear function of the force applied to the steering wheel up to a cut-out point, above which the servomotor pressure rises sharply to a maximum value.

Abstract: A dial operated air pressure regulator produces forward, hold and reverse signals in an air operated control circuit which creates corresponding conditions in a hydraulic circuit. The regulator has a pair of spring loaded valves which slide axially in a pair of valve cylinders which in turn control the air flow in the circuit. The valves are depressed by face cams moulded into the dial; rotation of the dial in one direction causes one cam to operate one valve and produces a forward signal; rotation in the opposite direction causes the other cam to operate the associated valve to create the reverse signal; when neither valve operates, the hold signal results.

Abstract: A control mechanism (48) is provided to controllably maintain a constant force on an actuator (18) and provide fluid flow to a downstream control valve (24) by controlling a pilot differential pressure between first and second ends (38,40) of a pilot operated control valve (14). A two position valve (56,66) acting in response to a predetermined pressure level in the actuator (18) modulatably controls the flow of pressurized pilot fluid to the pilot operated control valve (14) to position the pilot operated control valve (14). This maintains the pressure in the actuator (18) at the predetermined pressure level and passes the excess flow of fluid from a source (12) to the downstream control valve (24).

Abstract: The regulator is designed to control the flow of a pressurized fluid between a source of said fluid which feeds it at a feed pressure, and a user device in which the fluid is at a utilization pressure which depends on the operating conditions of the device; the regulator also comprises a valve element mobile in the direction of its axis and arranged to vary the degree of closure of an orifice between a feed chamber and a utilization chamber, and a first and second cavity in which there is housed a first and second active surface respectively, on one of which there acts the utilization pressure and on the other of which there acts a control pressure arranged to control the movement of the valve element.

Abstract: A fluid power control system (17) having an improved control valve (20) providing reduced regulated pressure fluid selectively from a high pressure pump supply (P) or the fluid motor (10) under conditions wherein the pump supply has failed to supply the desired pressurized fluid. The system utilizes a control valve (20) having a spool (29) provided with first transfer passage (41) and second transfer passage (42). The first transfer passage is adjustably throttled as a result of movement of the spool relative to an adjacent inlet port (37) and the second transfer passage (42) is adjustably throttled by movement of the spool relative to an adjacent inlet port (38). Inlet port (37) is connected to the high pressure fluid supply P and inlet port (38) is connected to the head end (13) of the cylinder (11) of the fluid motor through a check valve (44).

Abstract: A hydraulic control system comprising a hydraulic actuator having opposed openings adapted to alternately function as inlets and outlets for moving the element of the actuator in opposite directions, a pump for supplying fluid to said actuator, pilot operated meter-in valve means to which the fluid from the pump is supplied for controlling the direction of movement of the actuator, pilot operated meter-out valve means associated with each opening of the actuator for controlling the flow out of said actuator,and means for sensing a predetermined drop in a line supplying fluid to one opening of the actuator caused by a runaway load in one direction and operating the meter-out valve means to interrupt flow out of the other opening of the actuator.

Abstract: A pneumatic circuit includes a source of fluid pressure 11, a selector valve 12, a control valve 14, and a power cylinder 15. The control valve 14 includes main valves 35 and 45 and a pilot interlock valve 27. The main valves 35 and 45 include a main inlet port 36, a main exhaust port 38, and cylinder ports 37 and 47. The pilot interlock valve 27 includes a pilot inlet port 28, an interlock port 30, and a signal port 29 which communicates with signal chambers 39 and 49. The control valve 14 is mounted on a motor vehicle transmission, and a mechanical actuator 16 moves between an extended position when the transmission is out of the neutral position and a retracted position when the transmission is in the neutral position. When the actuator 16 is in the extended position, the pilot interlock valve 27 is retained in an interlocked position to maintain the pressure condition existing in the signal chambers 39 and 49.

Abstract: An apparatus for restricting the velocity of movement of the piston of a servo-controlled operating hydraulic unit, when the piston approaches at least its one end position in the cylinder, by means of a hydraulic sensor fixedly mounted on one of the machine parts which is shifted with respect to each other by means of the operating hydraulic unit, and is coupled by the intermediary of a non-return valve to the servo-circuit. When the piston of the operating hydraulic unit approaches its end position in the cylinder, the hydraulic sensor is actuated by the second of the above-mentioned machine parts, whereby a pressure is established in the cylinder of the hydraulic sensor which exceeds the servo-pressure. A valve senses the pressure difference between the servo-pressure and the pressure established by means of the hydraulic sensor and throttles the servo-flow to the main valve of the operating hydraulic unit the main valve thereby throttling the pressure medium supply to the operating hydraulic unit.

Abstract: A hydraulic draft control system for use on a tractor and having a pilot valve regulating flow and pressure for automatically operating a draft control valve. The pilot valve opens and closes in response to draft loads sensed on the tractor to control the opening and closing of the control valve for raising and lowering of an implement on the tractor.

Abstract: A dashpot assembly has a movable cylindrical element mounted within a housing. The movable element has a chamber with a first opening for restricting flow of fluid into the chamber and a second opening for permitting rapid flow of fluid out of the chamber. An enlarged head is disposed inside the chamber and is coupled to a poppet with a spring coupled between the poppet and the movable element. When the poppet moves in a direction away from the movable element, the enlarged head closes the second opening and pulls the element. Fluid then flows into the chamber only through the restricted first opening, thereby damping the rate of movement of the poppet. When the poppet moves in a direction toward the movable element, the enlarged head opens the second opening and the spring is effective to move the element in the same direction; fluid flows unrestricted through the second opening, thereby permitting an undamped movement of the poppet.

Abstract: A hydraulic drive for an electrical switch is disclosed including magnetically operated control signal organs for initiating closing and opening of the electrical switch which is hydraulically driven by a drive with a differential piston moving in a drive cylinder. A switch-over control valve is employed for selectively pressurizing and depressurizing a larger end face of the piston. In order to prevent "pumping" of the switch by such a switch drive system according to the present invention, the control signal organ which is opened in connection with the initiation of the closing of the switch is manipulated hydraulically at approximately the same time as the pressurization by the switch-over control valve of the larger piston end face of the differential piston of the drive commences. The hydraulic manipulation shifts the control signal organ back into a closed position. This arrangement permits at most only one on-off switching cycle to occur, and thus "pumping" of the switch is prevented.

Abstract: A fluidic Repeater, includes a rotary transmitter, a responder, and a rotary feedback.Various constructional features useful in conjunction with the system are disclosed.

Abstract: A regulating device for a working cylinder of an agricultural vehicle comprises a directional multiway control valve which controls the flow of a working fluid to the cylinder via a switch valve which is normally biased into its closing position and held in its open position by a pressure difference applied thereto from a throttle arranged in a main control conduit connected to a control fluid pump. One end of the spool of the directional multiway control valve is spring biased into a lowering position and its other end is controlled by a setting cylinder which in turn is controlled by an adjustment pressure having an actual pressure component and a desired pressure component. Means for setting the adjustment pressure includes an adjustable pressure reducing valve connected in series in the main control conduit with an adjustable pressure relief valve, the adjustment means of the latter being controlled by an actual power measuring unit on the vehicle.

Abstract: The invention relates to an electrohydraulic control assembly of the type having a slide valve unit for controlling the operating direction of a hydraulic servomotor. The assembly includes a bridge circuit between the pressure source and the drain tank which has a pressure operated valve in each of its four branches. Diagonally opposite bridge terminals between the supply and exhaust branches of the bridge circuit are connected operating chambers on opposite sides of the slide valve unit. The bridge circuit valves are operated by solenoid valves to achieve selective directional operation of the slide valve unit.

Abstract: A system for regulating the flow of a fluid in dependence of an input signal includes a valve housing, a valve between an inlet and an outlet of the valve housing, a cylinder substantially closed off from the cartridge valve housing, and a piston in driving connection with the valve, and movable within the cylinder in opposite directions. A resilient device urges the piston to drive the cartridge valves so as to close the outlet , and a fluid control device communicates with a main fluid conduit and with first and second openings of the cylinder disposed on respective opposite sides of the piston. The valve housing inlet and a source of fluid are connected to the first and second openings of the cylinder, respectively, in a first active station of the fluid switch, but this connection is reversed in a second active station thereof; the first and second openings, and the source of fluid are blocked in a neutral station of the fluid switch.

Abstract: A safety valve is mounted on an underwater oil well and is remote-controlled from a central control station. The control station is connected to a receiving station, where the valve is disposed, via a single small-section hydraulic line which feeds, at a low rate of flow, a hydropneumatic accumulator for supplying an operating jack of the valve. A manostat switch at the receiving station controls a feed/bleed hydraulic relay of the jack in dependence on the pressures measured in the line at the receiving station. The invention finds application in oil valve safety operations.

Abstract: A hydraulic draft control system for use on a tractor and having a pilot valve regulating flow and pressure for automatically operating a draft control valve. The pilot valve opens and closes in response to draft loads sensed on the tractor to control the opening and closing of the control valve for raising and lowering of an implement on the tractor.

Abstract: A control arrangement for a hydraulically operated load lifting and lowering device includes precontrolled first valve means controlling flow of fluid from a source under pressure to a return conduit leading to a tank or to a working conduit leading to the device and a closer block in the working conduit, including a piston controlling flow of pressure fluid from the working conduit into the device, respectively flow of pressure fluid out of the device into the return conduit downstream of the piston. A throttle is arranged in the return conduit to produce upstream of the throttle a pressure acting on the piston but not on the slide of the first valve means, whereby without increasing the neutral fluid circulation pressure a uniform lowering of the load independent of the magnitude thereof may be obtained.

Abstract: A high volume valve for controlling flow of fluid from a source of fluid under pressure, such as in an accumulator, to an actuator used for testing specimens under high rates of loading. The valve includes a poppet type valve piston that is normally held in a closed position by hydraulic pressure behind the poppet, and when the pressure holding the poppet closed is released, the main supply of fluid under pressure acts on the poppet to open it very quickly. A second accumulator open to the opposite side of the poppet from the main source of pressure is utilized for controlling speed of opening of the valve. The amount the poppet opens also can be adjusted for controlling the rate of flow of fluid from the main source of pressure to the actuator.

Abstract: A hydraulic driving device of a circuit breaker which opens and closes a system in response to two signals is principally constructed of a cylinder, a piston, and a main control valve for controlling the motion of the piston. A spool adapted to slide within the main control valve has its motion controlled by four pressure faces. The first pressure face is normally subjected to a high oil pressure. The second pressure face receives a low oil pressure upon application of the first signal, and a high oil pressure upon release thereof. The third pressure face receives a high oil pressure upon application of the second signal, and a low oil pressure upon release thereof. A high or low oil pressure acts on the fourth pressure face in correspondence with the piston motion. The magnitudes of the forces on the respective pressure faces of the spool are set in a predetermined relationship.

Abstract: Booster providing both hydraulic feed-back and hydraulic feel-back in a two-stage operation in which we boost-brake a vehicle. Concentric, nesting, inner and outer control parts include, as the sliding outer part, a brake-pedal-connected input signal spool or sleeve for developing a desired signal pressure varying linearly along the length of, and therefore according to the sliding position of, the sleeve; the inner part constitutes a captive, telescoping metering spool with its ends in corresponding ends of the spool sleeve.

Abstract: PCT No. PCT/US79/00664 Sec. 371 Date Aug. 30, 1979 Sec. 102(e) Date Aug. 30, 1979 PCT Filed Aug. 30, 1979 PCT Pub. No. WO81/00600 PCT Pub. Date Mar. 5, 1981A lock valve (10) for use in a hydraulic system (90) for positioning the work implement of an earth working machine which includes first and second check valves (28, 30) and a piston section (60, 70, 62, 72) for each operable by pilot fluid. In a first mode, the piston sections (60, 70, 62, 72) permit seating of both check valves, while in a second mode, the piston sections interlock so that only one check valve can seat. The lock valve (10) operates in a hydraulic system (90) to lock a work implement, such as a blade for a motor grader, in a fixed position during a first operating mode, while providing a connection from one end of an implement actuator to vent during a second operating mode to insure that a shock absorbing means for the implement hydraulic system maintains a full shock absorbing capacity.

Abstract: PCT No. PCT/US79/00859 Sec. 371 Date Oct. 15, 1979 Sec. 102(e) Date Oct. 15, 1979 PCT Filed Oct. 15, 1979 PCT Pub. No. WO81/01034 PCT Pub. Date Apr. 16, 1981In prior art hydraulic systems, and in particular in hydraulic systems having a cylinder means for elevating and lowering a load, there exists the possibility that the hydraulic line from a control valve to the cylinder means could rupture, allowing the load to drop before the operator could react. The present invention solves this problem by providing a blocker valve (100) in the vent line (69) of a check valve (33,34) which check valve is interposed in the main line 27 between a cylinder means (12) and a control valve (21). The blocker valve (100) is responsive to the back pressure in the main line (27) from the check valve (33,34) to the control valve (27).

Abstract: A control valve unit (10) disclosed includes a slide mechanism (14) mounted on a base (40) of the unit, a control member (18) driven by a hydraulic linear actuator (12) controlled by the unit, and a control valve (22) that feeds hydraulic fluid to the actuator and has a deactivator (24) that is engaged and moved by a pair of slides (16a,b) of the slide mechanism under the impetus of the control member movement in order to terminate driving of the actuator at its limits of movement. The slide mechanism includes a slideway on the base and a pair of fixed stops (62a,b) between which the movable slides are supported on the slideway and biased by a helical spring (68) against the stops. The helical spring is aligned with openings (66) in the slides and the control member (18) extends through the spring and the slide openings. Lugs (76a,b) on the control member for moving the slides are preferably adjustable so as to permit adjustment of the limits of actuator movement.

Abstract: A programmed valve system for positioning control having a first two stage valve assembly operable for raising a load and a second two stage valve assembly for lowering the load. Each of the second stages has a poppet with a parabolic contour which is dimensioned with orifice parameters to provide substantially linear flow rate change for minimized shock when one of the second stage poppets closes and the other opens. In the raise assembly, the pilot stage outlet orifice has a cross-sectional area substantially larger than that of the inlet orifice so that the second stage poppet opens much more rapidly than the closing thereof thereby to minimize overshoot when the pilot stage is actuated to the open position.

Abstract: A simplified fail-fixed electrohydraulic servovalve for operating with a source of fluid under pressure, and a piston translatably disposed within a bore. The piston has a rod side face area which is less than its head side face area and translates in a first direction for electrical input signals above a first predetermined percent of a maximum rated input signal. At a second percent of the rated input signal, determined by the ratio of the piston rod side face area to the piston head side face area, the piston position is fixed. For electrical input signals greater than the second percent of the rated input signal the piston translates in the second direction. Any input signal below the first percent causes the piston to be fixed in place.

Abstract: A fluid operable hammer including variable volume exhaust chamber means for receiving motive fluid and improved motive fluid inlet and exhaust valve means cooperable with the exhaust chamber means.

Abstract: A fluidic repeater comprising: transmitter means, a responder, a single line for transmitting pressure signals between said transmitter means and responder, and means including a source of pressure fluid for causing a pressure fluid to flow through said line.

Abstract: A control valve unit (10) disclosed supplies hydraulic fluid to an actuator (12) in a manner that controls both acceleration and deceleration of the actuator movement. A supply valve (14, 22) of the unit is movable from a central closed position in opposite directions to open positions and back to the closed position by a servomechanism (16) and a control circuit (18) that operates the servomechanism to cooperatively control the supply of the hydraulic fluid to the actuator in a manner which controls both acceleration and deceleration of the actuator movement. A control member (62) of the servomechanism operates the supply valve and is moved in a controlled manner by cooperative operation of a pair of hydraulically operated pilot pistons (88a, b), a pair of acceleration control pistons (90a, b), and a pair of deceleration cams (84a, b). Directional and flow control valves (89, 92) of the control circuit operate the pilot pistons and the acceleration control pistons in cooperation with each other.

Abstract: A control circuit comprises pressurized fluid source (11), a two-position directional control valve (14) and an actuator (13), such as the pump of a hydrostatic transmission, connected to the fluid source and the control valve to be selectively actuated thereby.

Abstract: A control arrangement for a hydraulic force transmission, especially for a hydraulically operated lifting device on agricultural vehicles comprises, besides a main control slide, a pressure control slide and a blocking device, an auxiliary slide arranged in a bore of the pre-control slide. The hydraulic working fluid is fed from the main slide directly to the blocking device and a special arrangement of the auxiliary slide in the hydraulic control circuit permits a compact and simple construction of the control arrangement, while preventing tight throttling of the fluid in either direction of the flow.

Abstract: The steering system comprises at least one double-acting fluid cylinder, a directional control valve connected to the cylinder for alternately extending and retracting the cylinder and a hand metering unit for communicating a fluid steering signal to the directional control valve whereby an engine-driven pump is adapted to communicate pressurized fluid to the cylinder for steering purposes. A variable flow control valve is interconnected between the pump and the hand metering unit for communicating a variable fluid flow to the hand metering unit in proportion to the speed of the pump to vary the fluid steering signal whereby an operator can sense the speed of the pump. In the preferred embodiment of this invention, the variable flow control valve comprises a pair of spring-biased, reciprocal members which sense a differential pressure across the valve to control fluid flow through an outlet which is adapted to be connected to the hand metering unit.

Abstract: A delaying device for a fluid system for operating a hydraulic motor (10) wherein electrically operated pilot valves (39,40) are actuated by limit switches (13,13') in the motor to control flow through pilot lines (37,38) into a control block (20) and then to and from the motor, said delaying device comprising a dashpot cylinder (46) connected to said pilot lines for momentarily continuing to supply fluid to said control block (20) after pilot valve (39 or 40) is shut off.

Abstract: An electronically controlled pipe fracture safety device for operating devices which are fed by a hydraulic pump and which are actuated by a control slide value by means of hydraulic cylinders. Control lines branch off from lines which lead from the hydraulic pump via a control slide valve to the hydraulic cylinders, the control lines feeding the hydraulic medium to a differential flow monitor, on the piston of which a permanent magnet is fastened. The latter, by means of a reed contact as a result of a pressure difference existing between the control lines, which pressure difference is brought about by damage or fracture of a line, produces a signal in the NOR gate, the latter forming the input of a scoring logic. This signal retransmits a self-holding signal to NAND-gates which form a flip-flop. The self-holding signal causes deenergization of a relay and consequently an interruption of the current flow to the control slide valve and brings about the locking position of the latter.

Abstract: A spring brake actuator has a quick release clutch for deactivating the brake in absence of fluid pressure and a governing device operating the clutch in response to the relative pressures prevailing at the service brake and spring brake cylinders. The governing device comprises a biased pilot valve and a signal valve which permit alternate operation of the brake release clutch manually or automatically.

Abstract: A fluid repeater system may be balanced so that displacement of the load has a desired correspondence to displacement of the transmitter. This may be done by making the fluid resistance offerd to fluid flowing along a path from the source to the reservoir and through the feedback controlled directly by the load, exclusive of the resistance offered by such load feedback, approximately equal to that offered to fluid flowing along a path from the source to the reservoir and through the transmitter, exclusive of the resistance offered by such transmitter.

Abstract: A valve actuator is disclosed having a servo-motor which regulates the position of a main valve that controls steam supply to a turbine. A hydraulic input signal acts on a pilot valve within the valve actuator body to move a valve spool in response to the input signal. Movement of the valve spool permits oil to flow into a cylinder in which the servo-motor is located. The flow of oil into the cylinder causes a piston which is a part of the servo-motor to move upwardly. Movement of the servo-motor is regulated by a cam and follower arrangement which transfers the motion of the servo-motor to a valve sleeve. The valve sleeve, which has a differential piston area, shuts-off the supply of oil to the servo-motor. The cam and follower arrangement provides for a linear correlation between the hydraulic input signal and the operation of the servo-motor. Increased closing forces provided by the differential piston reduce vibration of the valve sleeve and the servo-motor.

Abstract: An improved pneumatic operating mechanism construction is provided including the usual stationary operating cylinder with a movable reciprocally-operable driving piston member movable therewithin, and having an extremely-fast pneumatic valve-device cooperable with a movable valve-sealing member attached to, and carried by, the driving side of the movable driving piston. Additionally, a valve-piston bore is provided internally within the stationary valve-housing member, within which reciprocally pneumatically operates the movable valve piston.An exhaust-port opening is provided being pneumatically communicating to the region interposed between the movable valve piston and the movable valve-sealing member, which is carried by the movable driving piston. The result is an extremely-fast valve action providing for high-pressure operating fluid, such as compressed air, for example, to be provided to the driving face of the movable driving piston.

Abstract: A vibration-free hydraulic power system having an opposing pair of pistons adapted to be moved in unison with the same stroke and equal force, but in opposite directions, one of the pistons being operatively connected to an external mass to be moved, the other of the pistons being operatively connected to a reactive mass the weight of which is identical to the weight of the mass being moved, the reactive mass acting to maintain the system in an equilibrium state during its complete operating cycle, the system incorporating a pair of control valves each having a series of sequentially acting valve elements which control fluid flow to and from the system, the pistons and control valves working at all times against solid columns of fluid under positive but variable pressure.

Abstract: A regulation system for steam turbines which includes a servomotor controlled by a servovalve (1) and two safety valves (31, 31') controlled by two electrically-operated valves (19, 19'). When the control inlet (7) of the servomotor is connected to the drain pipe (6) by at least one of the safety valves, the high-pressure fluid supply to the servovalve is simultaneously cut and the high-pressure fluid source is thereby prevented from discharging directly into the drain pipe. This enables high-pressure fluid sources having a low discharge rate to be used.

Abstract: A hydraulic control system particularly suitable for controlling the acceleration and velocity of a load such as the plunger of die casting equipment is described. The load is controlled by a hydraulic ram which in turn is controlled by a main valve of the kind in which the rate of flow of fluid to the load is directly proportional to the rate of flow of pilot fluid thereto. Pilot fluid flows through an auxiliary valve and a restrictor. The restrictor is adjusted to determine the maximum rate of flow and the rate at which the auxiliary valve opens is adjusted to determine the rate of change of flow.

Abstract: A hydraulic system including a hydraulic motor having a port adapted to be connected to a reservoir and a hydraulic fluid pump. A normally closed check valve connects the port to the reservoir and includes two, hydraulically opposed, differential surfaces, one being smaller than the other and being disposed to be responsive to pressure at the port. Included is a normally closed, pilot-operated, first metering valve having an inlet and an outlet and a second metering valve also having an inlet and an outlet along with a shiftable metering element interposed therebetween. A spring biases the element towards a position minimizing flow between the inlet and the outlet and a pressure responsive surface is disposed on the element in bucking relation to the spring. The first valve inlet is connected to the second valve outlet and to a larger surface of the check valve and the port is connected to the second valve inlet as well as connected to direct pressure to the second valve pressure responsive surface.

Abstract: The pulsator for hydraulic systems controlling actuating mechanisms has a housing accommodating a pusher made in the form of a piston with a rod, a delivery valve, a pneumatic piston displacing in the cavity connected to the pneumatic control system. Above the pusher piston there is an upper cavity communicating with a high-pressure main, and under the piston there is a lower cavity communicating with the actuating mechanism via a non-return valve. A stem is provided between the rod and the piston. Also made above the pusher piston is an auxiliary cavity which is an extension of the upper cavity, defined by a leading edge and connected to the actuating mechanism. Above the lower cavity of the pusher piston there is an annular cavity disposed coaxially with said cavity, separated from said cavity by the leading edge, connected to the valve controlling resetting of the pusher.

Abstract: The closure and trip pilot valves of a circuit-breaker control unit are actuated by a hydraulic device controlled by a pressure drop which appears in control lines in response to the transient opening of a drain electrovalve within a control cubicle. Thus the pressure-drop hydraulic signal transmitted from a single central control cubicle for closing or tripping a circuit-breaker dispenses with the need for any electrical system and permits the control of a plurality of circuit-breakers or breaker modules solely by means of small-section lines providing hydraulic connections between the central control cubicle and each breaker control unit.