Abstract: A longwall mining shield base lift method. The method includes removing an old wear pad and installing a new wear pad.

Abstract: A pneumatic valve apparatus for a compressed air device, including: a pneumatic solenoid valve having a housing body with a supply channel, a consumer channel and a vent channel, wherein the housing body surrounds a valve chamber, in which a valve body can be moved along a valve axis counter to the force of a valve spring by an actuator relative to a vent valve seat leading to the vent channel and relative to a supply valve seat leading to the supply channel, wherein in a first position, the valve body opens the valve chamber and the vent valve seat leading to a vent channel, and, in a second position, opens a supply channel leading to the supply valve seat and the valve chamber, wherein the housing body comprises a diffuser, which adjoins the vent valve seat leading to the vent channel.

Abstract: A relief valve 1 includes: a housing 6 connected to a supply-side connection pipe 4a and a discharge-side connection pipe 5a and has an inflow port 61c and an outflow port 62c; a valve seat (an opening rim 61a) provided in the housing 6; a main valve body 7 which is placed in the housing 6, and capable of cutting off communication between the inflow port 61c and the outflow port 62c in the housing 6 by being seated on the valve seat (the opening rim 61a); and a biasing member 8 that biases the main valve body 7 toward the valve seat (the opening rim 61a), wherein the inflow port 61c is provided in the housing 6 such that the inflow port 61c is decentered with respect to a central axis line of the main valve body 7 in a direction in which a supply pipe 4 extends.

Abstract: The present invention discloses a compressor comprising: an outer pipe being connected from an outside to pass through the vessel; an inner pipe being closely inserted into the outer pipe; a compression mechanism including a suction hole formed of a blind hole and a suction valve in the suction hole. The suction valve includes a seal on a side facing an opening of the suction hole to seal an entire end of the inner pipe on a side facing the suction valve when the compressor stops.

Abstract: A stimulation tool for dislodging material from a perforation formed through a tubular disposed in a wellbore includes a main body formed at least in part from a material that is buoyant in a wellbore fluid, a ballast, a magnet, and a pressure pulse generator. The tool is configured to descend downhole by force of gravity when the ballast is attached and couple, by the magnet, to an interior surface of the tubular upon arrival at a downhole location proximate the perforation. When the tool is coupled by the magnet to the interior of the tubular, the tool transmits pressure pulses from the pressure pulse generator into the perforation, thereby dislodging material from the perforation. The tool de-couples from the interior surface and releases the ballast, thereby permitting the tool to ascend uphole, driven at least partially by a buoyant force exerted by the wellbore fluids.

Abstract: A valve assembly (1) comprising: a common housing having a first side (8a), a second side (8b), an inlet port (2) and an outlet port (3); the valve assembly (1) comprising a first pair of valve members or poppets (4a, 4c) and a second pair of valve members or poppets (4b, 4d), a first pair of valve seats (5a, 5c) for cooperation with the first pair of valve members or poppets (4a, 4c), and a second pair of valve seats (5b, 5d) for cooperation with the second pair of valve members or poppets (4b, 4d); a central flow diverter (13c) disposed in between the first pair of valve members or poppets (4a, 4c) and the second pair of valve seats (5b, 5d), the central flow diverter (13c) defining a first side (11a) of the valve assembly (1) and a second side (11b) of the valve assembly (1).

Abstract: A valve assembly for use in a fracturing pump including a valve member movable into and out of engagement with a valve seat body. The valve seat body includes an outer surface and an inner surface, the inner surface forming a fluid bore extending between a first end and a second end of the valve seat body. The body further includes a seating surface extending radially from the inner surface and facing the valve member, the seating surface having a recessed area. An insert is disposed in the recessed area forming at least a portion of the inner surface and at least portion of the seating surface. The valve seat body first end has a diameter different from a diameter valve seat body second. The difference between diameters allows the valve seat body outer surface to be supported by the fluid passageway.

Abstract: A flow control method and assembly for an oil or gas well comprises generating a pressure signature in the fluid in a bore of the well comprising a minimum rate of change of pressure, and transmitting the pressure signature to a control mechanism to trigger a change in the configuration of a flow control device in the bore in response to the detection of the pressure signature in the fluid. The flow control device can comprise a barrier, such as a flapper, sleeve, valve or similar. The pressure signature is transmitted via fluid flowing in the bore, typically being injected into the well, optionally during or before frac operations, via fluid being used for the frac operations. The control mechanism typically includes an RFID reader to receive RF signals from tags deployed in the fluid flowing in the bore.

Abstract: A solution is proposed for closing a mouth (125) of a container (110) of a liquid (105).

Abstract: A method for flood irrigation includes releasing water from a riser valve for flooding a portion of a field through a control of a corresponding riser device of a plurality of riser devices, wherein the corresponding riser device is deployed at a location proximate to the riser valve, receiving a wireless signal from a corresponding sensor device of a plurality of sensor devices for a detection of a flood condition, wherein the corresponding sensor device is deployed at a location proximate to where the water from the riser valve is expected to flood; and stopping the release of the water from the riser valve.

Abstract: A valve includes a body with an inlet at a first end of the body, and an outlet at a second end of the body. A first electrically resistive heating element is located in the inlet and heats a first fluid source to a temperature above 0 degrees C. A second electrically resistive heating element is located in the outlet and heats a second fluid source to a temperature above 0 degrees C.

Abstract: A method and an apparatus (280) for determining an estimate of a position of a hydraulic subsea actuator (200), wherein the hydraulic subsea actuator (200) has a fluid port (220) fluidly connected to a fluid source (260). The apparatus (280) comprises a hydraulic cylinder (310) connected in series between the fluid source (260) and the fluid port (220) of the hydraulic subsea actuator, and a movable piston (320) arranged in the second hydraulic cylinder (310), a position determining device, arranged to determine a position of the movable piston (320), and a signal processing device (350), arranged to calculate the estimate of the position of the hydraulic subsea actuator based on the position of the movable piston.

Abstract: Exemplary embodiments of a gas biased pressure regulator comprise a capsule subassembly and a regulator body. The regulator body is adapted to connect to a source of pressurized gas. The capsule subassembly is removably received within the regulator body and includes a capsule body and a piston. The piston is axially slidable between fluid release and fluid seal configurations. When the piston is in its fluid release configuration, an output chamber is placed in fluid communication with the source. When the piston is in its fluid seal configuration, the output chamber is sealed from fluid communication with the source. A pressurizable bias chamber within the capsule body contains a bias pressure urging the piston toward its fluid release configuration. Pressure from the source urges the piston toward its fluid seal configuration. The piston may also have a fluid charge configuration for facilitating the pressurization of the bias chamber.

Abstract: A multi-stage pressure regulator system. The system of the present invention provides for distribution of the Joules-Thomson (J-T) cooling effect between multiple stages. In the preferred embodiment of the present invention, the pressure is first reduced by a set ratio in one or more stages followed by an adjustable pressure output stage. The present invention thereby provides a system to control pressure reduction and thus prevent condensation (and associated distortion of a vapor composition sample) of a gas due to J-T cooling effect. The system of the present invention is particularly suitable for use placement (via, for example, a probe) within the source gas supply containment vessel, pipeline or the like, so that pressure reduction occurs at or near isothermal conditions, further lessening the likelihood of J-T condensation.

Abstract: A pressure control valve is provided with a valve main body (10) having a valve chamber (15) with a valve seat portion (14), a refrigerant inflow port (11) and a refrigerant outflow port (12), and a pressure response element (30) having a diaphragm (20) defining an upper surface of a valve chamber (15) and driving a valve body (17) and a lid-like member (35) defining a sealed pressure chamber (25) together with the diaphragm (20) and having a concave portion (36), an inert gas having a thermal expansion coefficient not more than a predetermined value is enclosed within said sealed pressure chamber (25), and an internal volume of the sealed pressure chamber is set such that the valve body (17) comes to a full-open state when that the pressure of the valve chamber (18) becomes a predetermined pressure or more higher than the pressure at which said valve body starts opening.

Abstract: A multi-stage pressure regulator in which pressure is first reduced by a set ratio in one or more stages followed by an adjustable pressure output stage. The system of the present invention provides for distribution of the Joules-Thomson (JT) cooling effect between multiple stages. The present invention thereby provides a system to control pressure reduction and thus prevent condensation (and associated distortion of a vapor composition sample) of a gas due to J-T cooling effect.

Abstract: Actuators, and corresponding methods and systems for controlling such actuators, provide independent valve control with a large initial or opening force.

Abstract: Disclosed is a cylindrical, single-component two-stage regulator for controlling a pressure and a flow rate of a gas. The regulator includes a housing for holding the two stages having an ingress adapted for connection to a source of gas at a high input pressure and an egress adapted for supplying gas at a lower output pressure than the high input pressure; a first stage for reducing the pressure of the gas from the high input pressure to a fixed intermediate pressure; and a second stage for reducing the pressure of the gas from the fixed intermediate pressure to the lower output pressure and regulating the flow rate of the gas out of the egress. One application of the present invention is for use in scuba (Self-Contained Under-water Breathing Apparatus) applications, where it replaces the traditional two-component user-adjustable regulator. The regulator may be made out of stainless steel, and is small enough to fit into a user's mouthpiece.

Abstract: Disclosed is a cylindrical, single-component two-stage regulator for controlling a pressure and a flow rate of a gas. The regulator includes a housing for holding the two stages having an ingress adapted for connection to a source of gas at a high input pressure and an egress adapted for supplying gas at a lower output pressure than the high input pressure; a first stage for reducing the pressure of the gas from the high input pressure to a fixed intermediate pressure; and a second stage for reducing the pressure of the gas from the fixed intermediate pressure to the lower output pressure and regulating the flow rate of the gas out of the egress. One application of the present invention is for use in SCUBA (Self-Contained Underwater Breathing Apparatus) applications, where it replaces the traditional two-component user-adjustable regulator. The regulator may be made out of stainless steel, and is small enough to fit into a user's mouthpiece.

Abstract: The invention relates to a re-configured valve design to accommodate a high volume of product in the delivery system and the dispensation of product upon the application of a predetermined vacuum condition on the downstream side of the valve.

Abstract: A pressure regulator having a housing that defines a gas inlet, a gas outlet, and a reference pressure connector. A diaphragm is provided in the housing, where the diaphragm defines, at least in part, a reference pressure chamber. In some illustrative embodiments, the reference pressure connector fluidly references the reference pressure chamber to a first pressure via a first orifice, and to a second pressure via a second bleed orifice. A gas valve incorporating a pressure regulator is also disclosed.

Abstract: A gas pressure regulator comprises a main body having a first, gas inlet pipe and a second, gas outlet pipe, a calibrated gas passage through which gas flows from the first pipe to the second pipe, a shutter housed at least partially in the main body and mobile lengthwise along a first defined line to adjust the opening of the calibrated passage, a device for actuating the shutter and a regulator spring unit opposing the movement of the shutter.

Abstract: The present invention relates to a breath controlled air inlet valve for controlling a flow of air supplied to a wearer of a facemask, the valve permitting the flow of air when a wearer breathes in and restricting the flow of air when the wearer breathes out. The valve includes an inlet, an outlet, one or more pivotable shutters, and a shutter articulating mechanism for articulating the one or more shutters between an open state and a closed state. The shutter articulation mechanism actuates in response to the respiration of the wearer. The valve also enables a positive pressure to be maintained within the facemask by permitting an amount of air to flow around the one or more shutters when the one or more shutters are in the closed state.

Abstract: An automatic shut off circuit for controlling the flow of a gas through a gas separation system is disclosed. The gas separation system includes a gas separation module for separating nitrogen from air, and a non-electric automatic shut off circuit for controlling the delivery of air to the gas separation module. The non-electric automatic shut off circuit includes a pneumatically operated valve that enables or inhibits a flow of air to the gas separation module, and a pneumatic pressure switch operatively coupled to the pneumatically operated valve, wherein the pneumatic pressure switch monitors a pressure indicative of a demand for nitrogen, and the pneumatic pressure switch commands the pneumatically operated valve to enable or inhibit the flow of air based on the monitored pressure.

Abstract: Improved actuators and valve control systems, and methods for controlling actuators and/or engine valves, are disclosed. In addition to the inherent capability of timing control, the ability to provide continuous valve lift or stroke control greatly improves engine achieve fuel economy, emission and performance. The power-off state of the actuator is at the minimum stroke, from which an easy start-up can be directly executed. The minimum stroke is also very beneficial to achieve efficient low load operation. Even with continuous lift variation, the present invention is able to keep the spring force neutral or zero point in the center of a stroke, thus maintaining an efficient scheme of energy conversion and recovery through the pendulum action. When in compression braking or other high engine cylinder air pressure working mode, the invention is able to supply necessary force to open the engine valve.

Abstract: A safety shut-off device for sections of fluid circuits, which in case of damage or the like, have to shut off from each other on safety considerations. The safety shut-off device includes at least two valves connected to each other via a control chamber. A first pressure differential with the control chamber closes the valves and a second pressure differential, which is greater than the first, opens the valves.

Abstract: Improved actuators and valve control systems, and methods for controlling actuators and/or engine valves, are disclosed. In addition to the inherent capability of timing control, the ability to provide continuous valve lift or stroke control greatly improves engine achieve fuel economy, emission and performance. The power-off state of the actuator is at the minimum stroke, from which an easy start-up can be directly executed. The minimum stroke is also very beneficial to achieve efficient low load operation. Even with continuous lift variation, the present invention is able to keep the spring force neutral or zero point in the center of a stroke, thus maintaining an efficient scheme of energy conversion and recovery through the pendulum action. When in compression braking or other high engine cylinder air pressure working mode, the invention is able to supply necessary force to open the engine valve.

Abstract: A pressure reducing valve comprises a valve support member provided with a water passage, a valve seat fitting on the portion of the valve support member primary side relative to the secondary side end of the water passage, a cup-shaped valve body fitting on the secondary side end of the valve support member to slide and capable of abutting the valve seat at the open end, while enclosing the secondary side end of the water passage at the cylindrical portion, a seal member for sealing the sliding contact part between the valve support member and the valve body, and a resilient member disposed in the valve body to force the valve body away from the valve seat.

Abstract: Improved actuators and valve control systems, and methods for controlling actuators and/or engine valves, are disclosed. In addition to the inherent capability of timing control, the ability to provide continuous valve lift or stroke control greatly improves engine achieve fuel economy, emission and performance. The power-off state of the actuator is at the minimum stroke, from which an easy start-up can be directly executed. The minimum stroke is also very beneficial to achieve efficient low load operation. Even with continuous lift variation, the present invention is able to keep the spring force neutral or zero point in the center of a stroke, thus maintaining an efficient scheme of energy conversion and recovery through the pendulum action. When in compression braking or other high engine cylinder air pressure working mode, the invention is able to supply necessary force to open the engine valve.

Abstract: Actuators, and corresponding methods and systems for controlling such actuators, provide independent lift and timing control with minimum energy consumption, while supplying sufficient supplemental energy to overcome friction. In an exemplary embodiment, an actuation cylinder in a housing defines a longitudinal axis and having first and second ends in first and second directions. An actuation piston in the cylinder, with first and second surfaces, is moveable along the longitudinal axis. First and second actuation springs bias the actuation piston in the first and second directions, respectively. A first fluid space is defined by the first end of the actuation cylinder and the first surface of the actuation piston, and a second fluid space is defined by the second end of the actuation cylinder and the second surface of the actuation piston.

Abstract: A pipeline assembly for transporting a fluid such as oil, gas and water along a fluid path extending in the pipeline has a pressure control device incorporated therein. The pressure control device regulates the pressure of the fluid downstream the pressure control device to a predetermined pressure which is independent of, and less than, the pressure prevailing in the pipeline upstream of the pressure control device.

Abstract: A pressure relief valve has a housing fluidly connected to a pressurized system line carrying a system fluid. The housing carries a moveable piston and a valve member that both move between closed and open positions. The piston defines an upper chamber and a lower chamber within the housing. A pressurized fluid is supplied to the upper chamber to bias the piston toward the closed position. After the relief valve opens from excessive system pressure, the pressurized fluid is injected into the lower chamber to delay the return of the piston to the closed position. Initially, the fluid in the lower chamber flows through a check valve while the piston returns to the closed position. Then the fluid vent in the lower chamber vents from the lower chamber as the piston and valve member approach the closed position.

Abstract: A direct operated valve assembly is provided including a valve body having a pressurized inlet port in communication with a source of pressurized air, a cylinder port, a valve bore extending axially within the valve body, and a valve member supported within the valve bore and movable between predetermined positions within the valve bore to selectively direct pressurized air from said inlet port through the cylinder port. An actuator is also included that is mounted to the valve body for moving the valve member in a first direction and a biasing member disposed between the valve member and the valve body to provide a biasing force to the valve member in an opposite direction. Also, an air-assist passage is included for providing a source of pneumatic pressure that acts in combination with the biasing member to operatively move the valve member in a direction opposite to the movement induced by the actuator.

Abstract: A hydraulic damper for an automotive engine electromechanical cylinder valve 20 is provided. The hydraulic damper includes an inner piston 130 which is slidably mounted within an outer piston 110. The outer piston is slidably mounted within an interior hydraulic filled cavity 82 of a damper body 80. Movement of the valve body 20 along extreme positions causes the inner piston 130 to move the outer piston 110 within the interior cavity 82 to effectuate hydraulic damping of the valve body 20.

Abstract: A hydraulically controllable globe valve having a stem piston to which pressure can be applied by a spring connected to a pressure source, with the stem piston being able to move from a first end position in the direction of a second end position. Pressure control means are provided which maintain a constant pressure of the hydraulic spring means on the stem piston while the latter moves from the first end position in the direction of the second end position by connecting the hydraulic spring means to a pressure source during a variable portion of the valve lift. The valve can be used, for example, as a gas exchange valve in a reciprocating engine.

Abstract: An apparatus for and a method of introducing a gas into a vacuum processing chamber are provided. In one aspect, a processing apparatus is provided that includes a vacuum processing chamber, a first source of gas coupled to the vacuum processing chamber, and a fluid actuated valve for regulating the flow of the gas from the first source of gas to the vacuum processing chamber. The fluid actuated valve is operable to open in response to a flow of an actuating fluid and has a minimum valve opening pressure. A valve is provided for enabling the actuating fluid to flow to the fluid actuated valve. A controller is provided for selectively modulating the flow of the actuating fluid to the fluid actuated valve whereby the pressure of the actuating fluid is increased incrementally from an initial pressure to at least the minimum valve opening pressure. The apparatus reduces the risk of troublesome gas bursts in vacuum processing chambers.

Abstract: A valve for controlling fluids is embodied with a piezoelectric actuator (3) for actuating a valve member (2) that on one end has a valve head (7), forming a valve closing member, that cooperates with a seat (8) provided on the valve body (6) for opening and closing the valve (1). On a side of the piezoelectric actuator (3) remote from the valve member (2), a hydraulic chamber (21) is provided, which communicates, via at least one hydraulic line (23), with a bore (5) of the valve member (2) that is sealed from the piezoelectric actuator (3), and into which bore a piston (20) connected to the piezoelectric actuator (3) can plunge; the hydraulic chamber (21) is embodied as a hydraulic spring, which with its spring force on the piston (20) connected to the piezoelectric actuator (3) act as the prestressing element and the tolerance compensating element. The valve is intended in particular as a component of a fuel injection valve.

Abstract: A valve device for low-viscosity to high-viscosity fluids, especially for fluid plastic components of plastic mixtures consisting of one or more components, with a valve housing having a fluid inflow and a dosaging valve, which has a dosing nozzle that can optionally be closed or opened by a closing element, as well as a pressure control device which acts on the fluid in the fluid inflow.

Abstract: A hydraulically controllable globe valve having a stem piston to which pressure can be applied by a spring connected to a pressure source, with the stem piston being able to move from a first end position in the direction of a second end position. Pressure control means are provided which maintain a constant pressure of the hydraulic spring means on the stem piston while the latter moves from the first end position in the direction of the second end position by connecting the hydraulic spring means to a pressure source during a variable portion of the valve lift. The valve can be used, for example, as a gas exchange valve in a reciprocating engine.

Abstract: A poultry drinker system includes a number of drinker lines each supplied from a common high pressure water supply through a water pressure regulator. Each regulator includes a reference spring establishing a default minimum water pressure. A centralized remote control system provides regulated low pressure air to the water pressure regulators to augment the reference spring force and remotely adjust the water pressure in the drinker lines. The remote control system periodically applies higher pressure air to the water pressure regulators to increase water pressure and flow rates and sequentially flush the drinker lines. The remote control system includes a source of high pressure air, an air pressure regulator for supplying lower pressure air and a stack of 3-way valves for applying low or high pressure air to each water pressure regulator.

Abstract: The present invention relates to an air pressure regulator, characterized in that a regulator made of a piston body connected with a return spring is disposed at the top of a main body, wherein the high-pressure gas flowing from the primary pressure chamber to the secondary pressure chamber can be controlled by means that the secondary pressure inside of the closed space created by the piston body and the top of the main body exerts a stable and balanced effect on the piston body which raises or lowers the plug assembly, and that a stable output and a high accuracy of the secondary pressure can be ensured by means that the resilience of the return spring and the gas pressure creates a coordination effect without being influenced by the pressure difference created by the change of the internal pressure inside steel cylinder after bottling, so that the using life thereof can be extended and its safety can also be enhanced.

Abstract: A low cost diaphragm actuated absolute pressure regulator. The regulator comprises a housing having first and second sections that are secured together. The first section has a cavity and a diaphragm that seals the cavity and first section of the housing. An O-ring seal is disposed in a groove of the first section that seals against the diaphragm. The second section of the housing houses a movable and sealable vent plug that moves in response to movement of the diaphragm, and one or more vent openings for venting the interior of the second section to external pressure in response to motion of the diaphragm. The pressure regulator may be preferentially used in an upper atmospheric system that needs to maintain a specified pressure, but requires venting capabilities. Such systems include missiles that fly into the upper atmosphere.

Abstract: A pressure reducing valve 30 comprises a body unit 32, a bonnet unit 36, and an operating unit 38 having a handle 126. The pressure reducing valve 30 further comprises a first diaphragm 84, a second diaphragm 86, a third diaphragm 100, and a fourth diaphragm 102 which are provided to extend in the body unit 32 while being separated from each other by predetermined spacing distances, and a nozzle 106 and a flapper 110 which are arranged in a third diaphragm chamber 116.

Abstract: The present invention uses a regulator in the form of dispensing check valve and a flow restriction arrangement to provide a virtually fail safe system for preventing hazardous discharge of fluid from a pressurized cylinder or tank. A diaphragm controls the movement of a check valve element to prevent discharge of gas from a tank unless a predetermined vacuum condition exists downstream of the check valve. A capillary tube or other structure that provides capillary size opening minimizes any discharge of gas in the unlikely event of a failure of the regulator. This system is particularly useful in the delivery of arsine gas and provides multiple safeguards against accidental discharge.

Abstract: The invention relates to a valve system for a space (1) which is under vacuum in relation to its surroundings (3), which valve system comprises a valve unit (7) which is intended to be arranged in association with a wall (2) which delimits the said space and has a wall opening (4) through the said wall, which valve unit comprises a valve (8) which is normally shut and closes the said wall opening but is arranged to be opened and allow air from the surroundings into the said space if the vacuum, i.e.

Abstract: A flow control device or valve used in a power steering system of an automotive vehicle. The flow control device comprises a housing formed with an axially extending hole in which a spool valve is movably disposed. A first pressure chamber is defined in the hole, with one end of the spool valve. A drain passage is opened to the first pressure chamber and closable with the spool valve. A second pressure chamber is defined in the hole, with the other end of the spool valve. A restricting orifice is provided to be communicated with the first pressure chamber. An introduction passage is formed to be communicated through the restricting orifice with a discharge passage and opened to the first pressure chamber. The pressure in the discharge passage is introduced to the second pressure chamber. A first spring is disposed in the second pressure chamber to bias the spool valve in a direction to close the drain passage. A spring holding member is movably and coaxially disposed in the axially extending hole.

Abstract: In a power steering system which has a fluid pump and a hydraulic actuator, there is used a flow control device which comprises a spool unit slidably received in a spool receiving bore in a manner to partition the bore into first and second pressure chambers. The spool unit comprises a hollow cylindrical outer spool slidably received in the spool receiving bore. The outer spool has a bottom portion exposed to the second pressure chamber. The bottom portion has an aperture formed therethrough. A cylindrical inner spool is incorporated with the outer spool. The inner spool includes a larger diameter portion slidably received in a major part of the outer spool and a smaller diameter portion slidably received in the aperture of the bottom portion of the outer spool. The inner spool is engaged with a control spring to be biased toward the first pressure chamber. A spring member is employed for biasing the outer and inner spools toward the second and first pressure chambers respectively.

Abstract: In a hydraulic valve control arrangement particularly of an internal combustion engine wherein the valve has a valve stem by which it is supported so as to be slideable between a closed and an open position and first there are provided first spring means biasing the valve in the closed position and second spring means providing an opening force which is transmitted via a valve tappet and an end of the valve tappet is received in a cylinder which is engaged by the second spring means so as to form a hydraulic force transmitting structure to which hydraulic fluid can be admitted for tensioning the second spring means. The valve tappet has a control piston received in a control chamber to which pressurized fluid is admitted which holds the control piston in either of its open or closed valve end positions and a pressure space is arranged adjacent the closed valve end positions of the control piston to which pressurized fluid can be admitted for initiating opening of the valve.

Abstract: In a hydraulic operating mechanism for a valve which comprises a valve stem with first spring means acting on the valve stem in the valve closing direction, and second spring means acting at least intermittently on the valve stem in a valve opening direction, the compressing force of the second spring means is controlled hydraulically during the operation of the valve control device. In order to keep the control forces required for operating the valve as low as possible over its entire operating range, the second spring means comprises a spring combination composed of at least two springs which have different spring forces providing for a maximum spring force of the second spring means at the start of the valve opening stroke.

Abstract: A pressure compensation valve is constructed with a valve establishing and blocking a communication between an inlet port and an outlet port, a pressure receiving chamber, a piston driven by a load pressure within the pressure receiving chamber and shifting the valve in blocking direction, an intermediate pressure receiving chamber communicated with the inlet port via a first conduit and pushing the valve in blocking direction by the pressure therein, and a pressure variable relief valve for relieving a pressurized fluid in the intermediate pressure chamber to the outlet port via a second conduit.