Abstract: A valve arrangement is provided which comprises a valve body and a flexible curtain member. The valve body defines at least one fluid flow conduit, and a transverse curtain member track. The flexible curtain member is slidable positioned within the curtain member track, with ends projecting outwardly therefrom. Opposite ends of the curtain member are anchored securely in position, to define a curtain member orientation having opposite roll-cups defined thereby, projecting outwardly from the curtain member track. As a result of the roll-cups, the curtain member can slide between first and second extreme positions, to operate the valve arrangement.

Abstract: A steam bypass valve system for a steam turbine. The system provides a supplemental hydraulic seating force to a fast acting bypass valve after the valve plug is positioned against the valve seat with a spring force. The system also provides for quick hydraulic relief in order to retain the fast opening characteristics of a single acting hydraulic valve.

Abstract: A choke valve for use on water injection wells is disclosed. The valve comprises a body, a sliding sleeve, in the body, a boss shaped plug, and a means for urging the sliding sleeve against the plug. The fluid path through the valve is largely straight, reducing wear on the valve, and the valve is devoid of screwed fittings.

Abstract: A temperature compensated fluid metering valve has a body including a ported sleeve in which a metering element is slidable, the thermal coefficient of expansion of the sleeve and metering element being identical and different from that of the body. The sleeve is secured at one of its ends to the body and a device for detecting the position of the metering element is secured to the body at the other end of the sleeve. The dimensions of the body and the coefficients of expansion are selected so a change in temperature results in an apparent position error signal from the device, this signal repositioning the metering element to compensate for changes in specific gravity of the metered fluid as a result of the temperature change.

Abstract: The spindle of a butterfly valve for controlling the supply of compressed air to the starter of a turbine aero-engine is rotated to open and close the valve by the linear movement of a slide in a cylinder in response to the pressure differential between a pair of chambers defined by the slide and the cylinder. A resilient mechanism is provided for holding the slide when the valve is closed and temporarily preventing movement of the slide to open the valve until a predetermined minimum pressure difference exists between the two chambers. The slide is then released and travels initially at high speed and then at a speed limited by a throttle venting the lower pressure chamber to atmosphere. This makes it possible to create a relatively high rate of increase in the pressure of air supplied to the starter at the commencement of opening of the butterfly valve while controlling the final rate of pressure rise. The device can thus be used equally with an inertia starter or a free wheel starter.

Abstract: A fuel flow control valve is adapted to control the flow of fuel in a spill line to control the amount of fuel usable in a two speed gas turbine. The valve includes fluid pressure operated valve means controlled by two variable volume fluid pressure chambers to provide appropriate fuel flow for `run` and `idle` conditions, and positioning means to automatically position the fluid pressure operated valve means when the control valve is at rest to provide a flow of fuel appropriate for `start-up` of the gas turbine that is greater than the flow required in the `idle` condition but less than that required in the `run` condition. Operating fluid pressures connected to the chambers may comprise either gaseous fluid pressures tapped from a stage of the compressor of the gas turbine or a combination of said gaseous pressure source and a liquid fluid pressure source preferably comprising a fuel pressure supply tapped from the fuel supply line to the gas turbine.

Abstract: A valve choke actuating device utilizes a stepping actuator with a feedback control system. A command signal and a feedback signal are compared to produce a train of electrical pulses proportional to the difference in the signals. The train of pulses are utilized to actuate piston-cylinder assemblies to control the opening of the choke.

Abstract: An air conditioner assembly of the type including an air flow housing, an air flow valve rotatably mounted in the housing, and an actuator mounted on the housing. The actuator includes a rod extending therefrom. The rod and valve include first and second complementary connector parts, respectively. The second connector part is connectable with the first connector part by rotation of the actuator through approximately 90.degree. about the axis of the rod from a first orientation to a second orientation. The assembly includes a first bayonet coupling on the housing and a second bayonet coupling on the actuator for coupling the actuator to the housing.

Abstract: A device for transmitting simultaneously to two parallel rods a motion with a single degree of freedom as a longitudinal translational motion from a sleeve surrounding the rods and which is itself subject to first and second degrees of freedom, a translational and a rotary motion, which includes a plate interconnecting the ends of the parallel rods, the plate lying perpendicularly to the axis of translational motion of the rods, and a connecting mechanism between the plate and the sleeve such that the connecting mechanism is adapted for transmitting only the translational motion to the plate.

Abstract: A fluid control valve apparatus comprises logic valve means including a valve housing, a first valve member defined in the valve housing, and an axially movable valve body arranged in the first valve chamber, with the valve body including opposite end portions and a conical surface portion brought into contact with the conical surface portion when the valve body is moved in a valve closing direction. First and second hydraulic fluid chambers are defined in the valve housing and communicate with each other when the conical surface portion is out of contact with the valve seat and out of communication when the conical surface portion contacts the valve seat. A first pilot chamber in the valve housing, adjacent one end portion of the valve body, biases the valve body in a closing direction by a first pilot pressure signal.

Abstract: A safety relief system for a valve in a vent or a main flowline. The safety relief system utilizes a main actuator (24) utilized primarily for a positive pressure condition and a vacuum actuator (96) in axial alignment with the main actuator (24) utilized exclusively for a negative pressure condition. The main valve member (18) has a stem (22) which extends within both actuators (24, 96) and diaphragms (26, 100) are connected to the stem (22) for movement of the valve member (18).

Abstract: Process for the control of turbidity currents, especially of high temperature lubricants in the form of graphite and polymers, suspended in water, with a viscosity of 1,000 to 20,000 cP at a temperature of up to 250 bars and a current velocity of up to 120 m/sec. Closing and opening times of 2 to 20 milliseconds are maintained. Apparatus for achieving the process, which is a switching-off valve having closing and opening times of 2 to 20 milliseconds. The switching-off valve preferably is a plunger valve.

Abstract: The pressure-medium-actuated valve has a pressure medium inlet, a pressure medium outlet and a cylinder. A piston which is connected to a lid is movable in the cylinder and subdivides the cylinder into a first piston chamber and a second piston chamber. Two relief lines, each comprising a control valve are connected to the piston chambers and extend to a pressure medium sink. A first connecting line comprising a control valve extends from the inlet to the first piston chamber and a second connecting line comprising a control valve extends from the inlet to the second piston chamber. A third connecting line is disposed in the wall of the valve body and extends at one end into the first connecting line. The other end of the third connecting line is connected to the cylinder at a place which, with the piston in the operative position, extends into the second piston chamber and, with the piston in the safety position, extends into the first piston chamber.

Abstract: A rotary valve and a method of forming a sleeve for such a valve. The valve for controlling fluid pressure to a power assisted steering gear has a rotor 3 mounted in the bore 2 of a sleeve 1 so that relative rotation between the rotor and sleeve controls fluid flow through ports 5, 6a, 6b and 7 to actuate the power assistance means. The port 7 is in the form of an axially extending slot in the bore 2, one end 18 of the slot 7 terminating within the bore and the other end opening into an end face 19 of the sleeve to alleviate the requirement for an annular recess (such as 8, 9 or 10) on the sleeve for supply of fluid to the slot 7 and thereby permitting a reduction in length of the sleeve. The slot 7 may be flat bottomed and inclined relative to the sleeve axis and the method comprises rectilinearly machining such a slot--preferably as a single pass with a broaching tool inclined relative to the sleeve axis.

Abstract: An air actuator device is provided for manually operable hydraulic valves having a valve spool moving in a bore in a valve housing in the form of an actuator housing adapted for attachment on the valve housing and having a bore carrying a piston coaxially engageable with the spool end, spaced openings in the actuator housing communicating with the bore therein to introduce air to act on opposite sides of the piston and resilient means on at least one side of the piston normally urging the piston and spool to a closed position.

Abstract: The pressure medium actuated valve has a pressure medium inlet port, an outlet port and a cylinder in which a piston connected to a closure member can slide. The piston sub-divides the cylinder into a first cylinder space and a second cylinder space. Two relief conduits, each containing a control valve are connected to the cylinder spaces and extend to a pressure medium sink. A first connecting conduit containing a control valve extends from the inlet port to the first cylinder space and a second connecting conduit containing a control valve extends from the inlet port to the second cylinder space. The second connecting conduit has a non-return valve through which pressure medium flows in the direction of the second cylinder space, a third connecting conduit being provided between the first and second connecting conduits.

Abstract: The difference in the pressure drop in a pneumatic discharge conduit (5) between at least one discharge outlet (3) into the conduit and a point 9 downstream of the discharge outlet caused by lading in the discharge conduit is used to control opening and closing of the lading outlet valve 13 to automatically control pneumatic unloading of lading from a container. In one application, the container is a railway hopper car having a plurality of pneumatic discharge outlets 52, 52' and 52" which discharge into a pneumatic discharge conduit.

Abstract: A hydraulic throttle valve is disclosed which includes a choke piston slideably mounted in a bore for movement between an open position and a closed position. A differential piston is coaxially mounted with respect to the choke piston, and a control valve is mounted for slideable movement in a second bore which is laterally spaced from and parallel to the first bore. The control valve is operated by an electromagnet to selectively direct a control fluid to either side of the differential piston, and thereby open or close the choke piston. A feedback spring arm interconnects the choke piston and the control valve, with the spring arm resisting the opening of the choke valve and with the resisting force being a function of the force applied to the control valve by the electromagnet. A balance of forces acting on the choke piston is thereby achieved, with the choke piston being opened to an extend functionally related to the magnitude of the input current to the electromagnet.

Abstract: A pair (20) of unidirection actuators are opposingly disposed coaxially about an elongated member (1) for controllably imparting a series of stepwise rotary movements thereto. An outer race (5) disposed within a housing (2) is rotationally reciprocated as a result of the axial reciprocation of a coaxial drive member (3) under the influence of reciprocation means (12, 15, 9). An overrunning clutch (6) converts the reciprocal rotary motion of the outer race (5) into a series of uniform unidirectional stepwise angular movements.

Abstract: An auxiliary controlled valve including a valve body (8) displaceable against a valve seat (9) disposed in a drilling string (6) to produce pressure pulses in drilling fluid renders possible a selective closing or opening of a low-resistance transmission section (12) which lies parallel to a main throttle section (10). The valve has a central passage which permits the passage of measuring instruments through the valve regardless of the particular position of a valve body (8). The valve body (8) is largely balanced out with regard to dynamic flow forces so that only a comparatively small actuating force is necessary.

Abstract: The servo-motor system is provided with an internal control line which communicates one control valve with a cylinder chamber which is connected to a control valve connected with an external control line. The internal control line permits the second valve to be actuated via the externally controlled control valve.

Abstract: A rotary type pumping machine such as a pump turbine in a pumped storage hydro-electric plant, wherein, when the pumping operation of the runner of the machine is started, compressed air is introduced into the runner chamber to depress the water surface in the runner chamber to facilitate the start up of the runner and, when the runner is accelerated to a predetermined speed, the air in the runner chamber is discharged through an air discharge valve to commence the pumping operation. Water pressure available in the water passageway on upper reservoir side of the runner chamber is applied to the valve closing mechanism of the air discharge valve. The valve opening force exerted by a valve operating mechanism and acting on the valve opening mechanism of the air discharge valve is selected to be greater than the valve closing force generated by the water pressure applied to the valve closing mechanism of the air discharge valve.

Abstract: A hydraulically operated valve which is operated open and closed by applying differential pressure to opposite end surfaces of an annular piston which moves a concentrically positioned valve operating plunger.

Abstract: A control valve and a multiple control system therefor for controlling a plurality of remotely positioned hydraulically actuated underwater devices. The control valve includes first and second equal size pilot pistons acted upon by first and second pilot ports, respectively, for moving the valve to either an open or closed position, and third and fourth unequal size pilot pistons acted upon by third and fourth pilot ports for moving the valve to either an open or closed position. The control valve may be operated in an electro-hydraulic control mode by the use of electrically actuated valves controlling the supply of fluid to the first and second ports. In addition, the control valve can be operated in a hydraulic mode by hydraulically controlling the supply of fluid to the third and fourth pilot ports.

Abstract: The plate valve has a housing forming an inlet spigot and an outlet spigot. A movable valve member provided with a closure plate and an orifice plate is movable radially of the spigots via servo-pistons which are rigidly connected to the valve member. The pistons are guided in cylinders disposed diametrically opposite one another on the spigots. The cylinders may be integrally formed with the plate valve housing or may be separably formed as cylinder heads.

Abstract: A hydraulic control system, particularly for controlling the operation of roof support props of a mine working, employs control devices operated manually to feed pressure fluid to the working chambers of the props to effect extension or retraction thereof. A two-state valve device is operated when the props are extended to ensure that the correct setting pressure is established. This valve device has a control piston which is actuated to cause the device to establish independent connection between the main fluid pressure line and the associated working chambers of the props charged with fluid by the initial operation of the control devices. The connection established by the valve device is maintained even if the control devices break connection between the chambers and the pressure line. When the correct setting pressure is reached, a further control piston of the valve device is actuated to break the connection established by the valve device ready for the next operative cycle.

Abstract: A compressed air-actuated valve means useful for attachment to devices used in chemical analysis wherein a piston actuates a suitably positioned slide member in the piston thrust direction. The slide member glides on a base member provided with spaced-apart holes that extend approximately perpendicular to the glide surface of the base member. The holes are connected to one another on the side of the base member facing the slide member via at least one appropriately arranged groove positioned in the slide facing the base member. Intake and discharge nozzles are connected with such holes on the opposite side of the base away from the slide member. The piston is a double-headed piston with each piston head being of a different diameter and each head being positioned at opposite ends of the slide member so that the slide member moves with the piston.

Abstract: An actuator is provided which is respondable to control fluid pressure for moving an operative means of a valve between open and closed positions. Valve means are movable between open and closed positions and communicate between the accumulator means and the fluid passage means to permit fluid control pressure charging of the accumulator chamber when the valve is in the open position and for preventing discharge of fluid pressure within the accumulator chamber when the valve is in the closed position. The valve is responsive to pressure differential between the accumulator chamber and the fluid passage means.

Abstract: A control valve system and method are disclosed for blowout preventers having an actuating piston for actuating the closing of the blowout preventer whereby the piston has an opening side and a closing side. The control valve system and method include a means for selectively directing fluid from the opening side of the actuating piston to the closing side of the actuating piston in order to reduce the fluid requirements for closing the blowout preventer and reduce in stalled horsepower requirements thereby.

Abstract: A multiport valve for a dust-collection system has a pair of axially spaced seats for two of the ports which can be selectively engaged by a valve member in the form of two oppositely convex shells adapted to bear against one another at their edges. In addition, the shells can be separated so that each engages one of the seats. The actuator for the valve member or plate comprises two telescoping members which can be collectively or individually shifted in the axial direction. These members may be connected by swivel joints to the valve plate.

Abstract: A rotary fluid pressure device is disclosed of the type including a valve housing (19) defining a pair of fluid ports (41,43) and a shuttle port (85). The device includes a fluid pressure actuated displacement mechanism (15), and a rotatable valve member (53) which provides fluid communication from one of the ports to expanding volume chambers (27) of the displacement mechanism, and from the contracting volume chambers to the other fluid port. The device includes a shuttle valve assembly including a shuttle piston (97) having end portions (103,105) disposed within a pair of fluid chambers (77,79). A dampening sleeve (115,121) is disposed about each end portion of the piston and cooperates therewith to define a dampening orifice (127,129) to prevent hunting during low pressure operation.

Abstract: A four way valve assembly is provided which includes a main valve member operable by independent pilot valve actuation. The independent pilot operation means that the main valve stroke can be varied over a relatively wide range, enabling the valve to be produced in a number of sizes without requiring redesign of the pilot valve portion of the valve. A pilot body is mounted to the main valve and has a movable plunger of a conventional solenoid actuator attached to it. The plunger extends within the pilot body and has a loose fitting pilot slide mounted to its free end. The relative loose fitting pilot slide reduces the need for close manufacturing tolerances for the component parts used in constructing the pilot valve portion of the valve. The pilot slide is maintained in sealed relationship with a wall of the pilot body by relatively high pressure fluid passing through the pilot valve body.

Abstract: A reversing valve construction having a housing provided with a movable valve member therein that is interconnected to a piston unit having opposed piston heads that define a main chamber of the housing therebetween. The housing has end portions respectively cooperating with the piston heads to define a pair of opposed control chambers therewith, the end portions respectively having valve seats leading to the control chambers in directions substantially transverse to the direction of movement of the piston unit in the housing. Each piston head has a flexible seal member secured between a front disc member and a backing plate of the respective piston head so that an integral peripheral skirt of that seal member is urged into sliding and sealing engagement with an internal peripheral surface of the housing by an annular resilient O-ring member carried by the respective piston head and radially engaging and urging its respective skirt radially outwardly into the sliding and sealing engagement.

Abstract: A diverter device for use in direction pumpdown or through the flowline (TFL) tools through a connector joining a main flowline to at least one branch flowline. The diverter member is pivoted by operation of a removable operator to allow movement of the tool string through a selected branch of the connector. A sealing system allows removal of the operator having to depressurize the flowlines joined at the connector. The manual operator can be easily padlocked in position. The hydraulic operator provides a rugged, reliable mechanism to translate linear movement of a hydraulic piston into rotary movement of the diverter.

Abstract: A fail-safe-open actuator for actuating valves and the like which comprises a pair of opposed cylinders joined to define piston chambers, the axes of which are generally perpendicular to a valve stem. Pistons in the cylinders are connected to the valve stem by toggle links, the pistons being resiliently urged toward the ends of the assembly which corresponds to an open-valve position. To close the valve, a pressurized fluid, such as air, is introduced into the piston chambers and to the pistons at sufficient pressure to counter the resilient means so as to move the pistons away from their rest, valve-open positions, and thus move the valve stem perpendicularly to the axis of the piston chamber. A handwheel is provided to manually close the valve by moving the pistons from their rest positions.A solenoid controlled pneumatic valve may be used to control the supply of pressurized fluid, such as air, to the actuator.

Abstract: A control valve which can randomly select any one of a plurality of conduits for controlling the flow to a single output port. The valve is comprised of base plate and a cover or bearing plate, which together form a housing having a cavity. A slider or block of the same shape, but slightly smaller than the cavity, is confined in, but may move freely in the cavity to align a port in the base plate with ports in the slider. The slider has a plurality of ports and as the slider is moved from one corner of the cavity to another, the ports in the slider are selectively aligned with the port in the base plate. Fluid conduits may be connected directly to the ports in the slider through an aperture in the bearing plate. Actuators in the walls of the cavity selectively move the slider from corner to corner. The actuators may be driven by any suitable means.

Abstract: A secondary air supply system for the exhaust system of an internal combustion engine having a catalytic converter with a three-way catalyst, having an air control valve which selectively supplies a part of compressed air to the exhaust system while relieving the rest of the air to the atmosphere, wherein the air control valve has a valve element balanced by oppositely acting springs to a neutral position where it supplies a predetermined amount of secondary air necessary to provide stoichiometric exhaust gases at a standard flow of exhaust gases and is shifted to opposite sides of the neutral position in accordance with oscillation of feedback control of the air/fuel ratio of exhaust gases.

Abstract: A control valve assembly (10) is provided for controlling a hydrostatic transmission including a fluid pump having a variable swashplate, a source of control fluid under pressure, and a servo system responsive to the control fluid for varying the swashplate of the fluid pump. The control valve includes a valve body (12), first (26) and second (28) fluid chambers disposed in the valve body, a first fluid passageway (30) disposed in the valve body for directing pressurized control fluid to the first and second fluid chambers and a valve member (16) located in the valve body for controlling the flow of control fluid to the servo system. The pressurized fluid in the first fluid chamber acts on the valve member to bias the valve member in a first direction and the pressurized fluid in the second chamber acts on the valve member to bias the valve member in the second direction opposite the first direction.

Abstract: A valve actuator has at least one piston in a cylindrical chamber that has a segmental skirt provided with transverse teeth on its chordal face meshing with lengthwise teeth on the hub of a rotor extending diametrically through the chamber with one rotor end exposed and provided with a portion for mating engagement with a valve stem portion when the valve is clamped to the actuator. Air is delivered into the chamber on opposite sides of the piston and the skirt is provided with anti-friction elements. Single and dual piston embodiments are disclosed as well as the use of springs by which the valve is operated in a wanted manner in the event of loss of piston operating pressures.

Abstract: A reversing valve construction having a housing provided with a movable valve member therein that is interconnected to a piston unit having opposed piston heads that define a main chamber of the housing therebetween. The housing has opposed ends respectively cooperating with the piston heads to define a pair of opposed control chambers therebetween, the ends respectively having valve seats leading to the control chambers. Each piston head has a flexible seal member secured between a front disc member and a backing plate of the respective piston head so that an integral peripheral skirt of that seal member is urged into sliding and sealing engagement with an internal peripheral surface of the housing by an annular resilient O-ring member carried by the respective piston head and radially engaging and urging its respective skirt radially outwardly into the sliding and sealing engagement. Such seal member for each piston head can be adapted to close a valve seat carried by a respective end of the housing.

Abstract: A ball valve including a valve housing, a valve seat retainer fitted in a fluid passageway of the valve housing and being movable forwardly and backwardly within a given distance along the direction of movement of pressurized fluid, a sealed chamber formed in a portion of a spacing defined by the rear wall of the valve seat retainer and the inner wall of the valve housing, a channel formed in the valve housing for communicating the sealed chamber and an upstream fluid passageway, and a switch valve for opening or closing the channel to allow or prohibit movement of fluid within the upstream fluid passageway toward the sealed chamber, to vary the pressure force of the pressurized fluid acting on the valve seat retainer in the direction of movement of the pressurized fluid, whereby the valve seat retainer and the valve seat are displaced in the direction of movement of the fluid so as to come into contact with the periphery of the ball-shaped valve member when the pressurized fluid enters into the sealed chambe

Abstract: A slide valve has a spool valve element that is moved unidirectionally to a sequence of three positions during its operating cycle. The valve structure and unidirectional motion of the spool provide a precompression of the fluid being handled. The valve structure also permits relief of excess downstream pressure. Preferably hydraulic liquid is used to drive, position, and reset the spool valve. The spool valve itself has a hollow body with one groove on its outside surface and a valve body with a port at one end that is always in communication with the hollow portion of the spool valve. The slide valve is especially designed for and preferably used in a liquid reaction molding system to direct a reagent between a source (e.g. reservoir) and a destination (e.g. a mixing head). When applied to such a reaction molding system each slide valve replaces three conventional ball valves and one check valve and yet provides the additional features of precompression and relief of excess pressure.

Abstract: A valve in which a blade having an opening is moved between two oval-shaped seals, each having a pair of spaced circular inner seals, all housed in a valve body. One set of aligned circular seals has a central opening flanked by two opposing and aligned openings through the valve body. When the opening of the blade is positioned in alignment with the opening through the seals and the body, the valve is, of course, opened. When the opening of the blade is repositioned opposite the other set of o-shaped seals, the valve is very tightly closed.

Abstract: An actuator for actuating valves and the like which comprises a pair of opposed cylinders, the axes of which are generally perpendicular to a valve stem. Pistons in the cylinders are connected to the valve stem by toggle links, the pistons being resiliently urged toward the center of the assembly which corresponds to a closed valve position. To open the valve, a fluid, such as air, is introduced between the pistons, so as to move them away from their rest (valve closed) positions. A handwheel is provided to manually open the valve by moving the pistons from their rest positions.A solenoid controlled pneumatic valve may be used to control the supply of air to the actuator. Either a failure in air pressure or an electrical failure will result in the pistons being urged to the rest positions and also result in closing the connected valve, i.e., the failure mode.

Abstract: A multiway switching valve includes a valve member which is mounted in an internal compartment of a housing member for displacement between two terminal positions. The valve member is retained in each of the terminal positions by a respective magnet, especially a permanent magnet of an annular configuration which bounds a passage in which a magnetically attractable portion of the valve member is received in the respective terminal position. The housing and valve members are provided with abutments which abut one another in each of the terminal positions, the abutments being so located that the magnetically attractable portions of the valve member are out of contact with the housing member even in the terminal positions of the housing member. The magnetically attractable portions of the valve member are so dimensioned as to be spaced from the annular magnets even when the valve member assumes the terminal positions thereof.

Abstract: A multi-position flow control valve comprises a control piston movable in a boring in two opposite directions. At each end of the boring a pressure chamber is provided accommodating a pressure spring supported on a spring collar that at its end facing the boring has a conical recess. Each recess accommodates a conical projection of a supporting rod that is slidably guided in a blind end bore provided in the control piston. A spring is arranged in the blind end to urge the supporting rod into engagement with the recess in the spring collar. If a pressure fluid is introduced into one pressure chamber, it displaces the piston and compresses the biasing spring in the other pressure chamber whereby the spring biased supporting rods remain in engagement with the recesses in the spring collars.

Abstract: Disclosed is an improved hydraulic control comprising a fail-to-neutral module. As is conventional, the hydraulic control comprises a main spool and a fluid flow path comprising a bridge circuit including a driver stage. The fail-to-neutral module comprises means defining a fail-to-neutral orifice which (a) is located in the fluid flow path upstream of the bridge circuit and (b) has a relatively large flow area but a maximum dimension smaller than the smallest orifice in the pilot stage. Preferably the means comprise a pin positioned through a hole, the pin and the hole both being circular in cross-section and coaxial, and the fail-to-neutral orifice is the clearance between the pin and the boundary of the hole.

Abstract: A control valve of an exhaust recirculation apparatus comprises an expansible vacuum chamber communicating with a venturi portion and having a first diaphragm and a spring urging the diaphragm to expand the chamber, an expansible exhaust pressure chamber having a second diaphragm disposed to oppose the first diaphragm at a distance and communicating with an exhaust inflow chamber, a control chamber disposed between the above chambers and defined by the first and second diaphragms and a frame mounting the first and second diaphragms thereon. The first and second diaphragms are connected by a bracket to which a seal member is secured through a block. In the control chamber is disposed a conduit one end of which has an opening facing the seal member with a gap therebetween, the other end communicates with a throttle portion and an exhaust gas recirculation valve provided in an exhaust recirculation passage.

Abstract: The present invention is directed to a solids handling valve for use in combination with lock hoppers utilized for conveying pulverized coal to a coal gasifier. The valve comprises a fluid-actuated flow control piston disposed within a housing and provided with a tapered primary seal having a recessed seat on the housing and a radially expandable fluid-actuated secondary seal. The valve seals are highly resistive to corrosion, erosion and abrasion by the solids, liquids, and gases associated with the gasification process so as to minimize valve failure.

Abstract: The four-way reversing valve is utilized in refrigerating systems for heat pump applications to interchange the heating and cooling effects of the evaporator and condenser. The three-way pilot valve controls application of high or low system pressure to the end of the chamber adjacent the large piston. The different areas of the two pistons result in movement of the slide valve to the left (both modifications) when high pressure is applied and to the right when low pressure is applied.