Abstract: Seat fittings for attaching seats to seat tracks in a vehicle and related systems and methods are described herein. An example seat fitting includes a body having a bottom surface to face a seat track, a locking stud, and a solenoid disposed in the body. The solenoid is operable to move the locking stud between a retracted position in which the locking stud is disposed in the body and an extended position in which the locking stud extends outward from the bottom surface of the body and into the seat track.

Abstract: A pressure-regulating valve includes a valve sleeve with first and second ends defining a longitudinal axis, a sense line, a sense piston, a main chamber, and first and second valve spools. The sleeve includes an axially aligned bore. The sense line is within the bore proximate the first end. The sense piston is within the bore between the sense line and the second end, and is configured to move along the longitudinal axis in response to pressure exerted by fluid in the sense line. The main chamber is within the bore between the sense piston and the second end, and includes supply and vent ports. The first valve spool is within the bore between the sense piston and the second end. The second valve spool is within the bore between the first valve spool and the second end.

Abstract: In pneumatic non-load quick dual-speed hydraulic jack, the small of piston ring (17) of hydraulic pump cylinder integrates with pump body (19) and external ring of step pump core (14) to form movable assembly. The middle part of step pump core (14) is provided with pump core step interface (8) used for conversion of hydraulic speed. The step hole on the same axis of pneumatic valve block on special pneumatic valve structure is provided with washer (48), button (49), pneumatic valve core (45), compressed spring (68) and valve core fastness set. The pneumatic valve parts can replace the hydraulic quick pump structure partially when the high-pressure air source is available. High-pressure air delivered to the oil reservoir of the external sleeve (4) presses the hydraulic oil into the oil chamber of oil cylinder, and thus facilitates the quick lift of jack piston under light load or empty load.

Abstract: An antagonistic fluid control system, wherein the system may comprise multiple antagonistic pressure control valves operable with a single actuator, or multiple pressure control valves operable with respective antagonistic actuators. The pressure control valves are configured to provide functional and efficiency advantages, and operate together to provide several operating or valving states. A first valving state comprises an active valving state configured to actively control the movement of the load. A second valving state comprises an inactive actuation state, wherein either the return and pressure ports of one pressure control valve are closed, or only the return ports of one pressure control valve are opened, to allow the other pressure control valve to operate in an active valving state. A third valving state comprises a passive valving state, wherein the pressure control valves are operated in a slosh mode configured to allow the load to freely move or dangle.

Abstract: The present invention describes, generally, a method and system for controlling the dynamics of an actuatable load functioning or operable within a servo or servo-type system, wherein the dynamics of the load are controlled by way of a unique asymmetric pressure control valve configured to provide intrinsic pressure regulation. The asymmetric pressure control valve, which may be referred to as a dynamic pressure regulator because of its capabilities, utilizes different sized free floating spools that are physically independent of one another and freely supported in interior cavities of respective corresponding different sized valving components that make up the valve body to regulate the pressures acting within the overall system between the control or pilot pressure and the load or load pressure.

Abstract: A lift axle control module is disclosed that is simpler than prior art lift axle control systems, and does not require cycling the input pressure to the regulator. The module includes a housing fluidly connected to a first pressurized air supply and having one chamber with a load bladder port, a second chamber with a lift bladder port, and a common vent port. A pilot pressure is selectively provided for switching the module between the retracted and deployed modes. When the control module is set to the retracted mode, the lift bladders are pressurized to the system pressure, and the load bladders are vented. When the control module is set to the deployed mode, the lift bladders are vented and the load bladders are inflated and maintained at the regulated pressure.

Abstract: The present invention describes, generally, a method and system for controlling the dynamics of an actuatable load functioning or operable within a servo or servo-type system, wherein the dynamics of the load are controlled by way of a unique pressure control valve configured to provide intrinsic pressure regulation. The pressure control valve, which may be referred to as a dynamic pressure regulator because of its capabilities, utilizes dual spools that are physically independent of one another and freely supported in the valve body to regulate the pressures acting within the overall system between the control or pilot pressure and the load or load pressure.

Abstract: A method and system for controlling the dynamics of an actuatable load operable within a servo or servo-type system, wherein the dynamics of the load are controlled by way of a unique pressure control valve configured to provide intrinsic pressure regulation, thus eliminating the need for electronically or mechanically user controlled systems. The pressure control valve, which may be referred to as a dynamic pressure regulator, utilizes dual spools that are physically independent of one another and freely supported in the valve body to regulate the pressures acting within the overall system between the control or pilot pressure and the load or load pressure. The dual spools function in cooperation with one another to maintain a state of equilibrium in the system, namely to keep pressure acting on or within the actuator (the load pressure), or the feedback pressure corresponding to the load pressure, the same as the pilot pressure.

Abstract: A method and system for controlling the dynamics of an actuatable load functioning or operable within a servo or servo-type system, wherein the dynamics of the load are controlled by way of a unique pressure control valve configured to provide intrinsic pressure regulation. The pressure control valve comprises dual spools physically independent of one another and freely supported in a valve body to regulate the pressures acting within the overall system between the control or pilot pressure and the load or load pressure. The dual spools of the pressure control valve, although physically independent of one another, function in cooperation with one another in an attempt to maintain a state of equilibrium in the system, namely to keep pressure acting on or within the actuator (the load pressure), or the feedback force corresponding to the load pressure, the same as the control or pilot pressure.

Abstract: A multi-stage telescoping transmission jack with a high flow, lower pressure air-over-oil pump.

Abstract: A hydraulic system comprises a pump having a fluid feed end a fluid release. Hydraulic actuator has an advance port and a retract port A directional converter is fluidically coupled between the pump and the hydraulic actuator. The converter has a housing having a plurality of fluid passages that terminates in a pump outlet port, a pump inlet port, a first actuator port, and a second actuator port. A plurality of valves is disposed within the fluid passages. The plurality of valves has a first position and a second position. In the first position, a fluid flow direction at the first actuator port is into said housing from the actuator and a second fluid direction and a second actuator port is out of the housing. When the switches are in a second position the fluid flow direction is out of the housing at The second actuator port.

Abstract: A protection system for a pipeline comprises a hydraulically actuated valve operable to switchably prevent a flow of fluid from a first section of the pipeline to a second section of the pipeline, a hydraulic fluid source for supplying hydraulic fluid to said hydraulically actuated valve to enable actuation thereof, a vent for venting hydraulic fluid from the hydraulically actuated valve, the hydraulically actuated valve being connected to the vent via a differential pressure valve to control venting of the hydraulically actuated valve, a pressure transfer barrier with a first port connected to the first section of the pipeline and a second port connected to said differential pressure valve, said differential pressure valve being supplied with hydraulic fluid at a reference pressure.

Abstract: An improved hydraulic valve for a camera dolly includes a valve pin having an extension within a valve housing to reduce vibration and noise and to reduce hydraulic closing forces. The valve pin is resiliently supported by e.g., rubber o-rings at both ends. Valve performance is improved as reducing hydraulic forces on the valve pin results in smooth valve operation, especially when opening the valve under heavy loading.

Abstract: An improved hydraulic valve for a camera dolly includes a valve pin having an extension within a valve housing to reduce vibration and noise and to reduce hydraulic closing forces. The valve pin is resiliently supported by e.g., rubber o-rings at both ends. Valve performance is improved as reducing hydraulic forces on the valve pin results in smooth valve operation, especially when opening the valve under heavy loading.

Abstract: A band controlled valve apparatus for controlling fluid flow from a source to a sink, including a base (12) having an upper surface and an aperture (16) extending from the upper surface through the base (12) allowing the flow of fluid from the source through the base (12) to the sink when the aperture (16) is not covered, an elongate flexible band (8) with a first portion (8a) in contact with the upper surface of the base (12) and a second portion (8b) extending forwardly of the first portion (8a) then upwardly and rearwardly above at least a part of the first portion (8a), the second portion (8b) being actuated to selectively move the second portion (8b) of the band (8) forwardly or rearwardly to cover or uncover, respectively, the aperture (16) with the first portion (8a) of the band (8) to thereby prevent or allow, respectively, fluid flow through the aperture (16).

Abstract: The present invention relates to a control apparatus for a construction machine such as a hydraulic shovel, and the control apparatus for a construction machine includes a revolving operation member for operating a construction machine revolving unit (14), a fluid pressure pump (2) and an accumulator (5) for accumulating working oil from the fluid pressure pump (2), a fluid pressure actuator (7) for driving the construction machine revolving unit (14) to revolve with the working oil from the fluid pressure pump (2) and the accumulator (5), a first control valve (8) interposed between the fluid pressure actuator (7) and the fluid pressure pump (2), a second control valve (11) for controlling an inflow condition of the fluid from the fluid pressure actuator (7) into the accumulator (5), and control means (9) including first valve control means (9a) for controlling the first control valve (8) and second valve control means (9b) for controlling the second control valve (11).

Abstract: A hydraulic system for working cylinders of construction equipment is disclosed. The system allows oil to be smoothly drained from a chamber of a working cylinder into an oil tank through a first passage or/and a second passage without being resisted during an operation of the cylinder. The system thus effectively and smoothly moves the working cylinder while improving operational efficiency and operational speed of the cylinder. When the system is used with a boom cylinder of a power excavator, the system effectively performs a boom-up or boom-down action without losing pressure.

Abstract: A hydraulic circuit in a monoblock structure for lifting and lowering a load has at least two electromagnetically actuatable proportional distributing valve elements, a check valve, a pressure balance for load-independent lifting of the load as an input element, a housing accommodating at least some of the elements and having at least one pump connection, at least one consumer connection, and at least one return connection, the proportional distributing valve elements being disposed parallel to one another, electromagnetic drives seated side-by-side on a same side and at a same height, the pressure balance having a piston which is disposed coaxially next to a longitudinal slide of a first one of the proportional distributing valve elements in a bore that guides and supports both the valve elements, the longitudinal slide of the first proportional distributing valve elements being spring-loaded, and at least one component for adjusting a prestressing and bracing of a spring on the housing of a control penetrat

Abstract: A servo valve arrangement with a high-pressure, low-pressure and motor connection and with a pressure control valve arranged between the high-pressure connection and motor connection and a return control valve arranged between the motor connection and low-pressure connection is provided. The pressure control valve normally is closed and the return control valve normally is open. The pressure control valve can be opened by a common actuating member whilst closing the return control valve. The valve arrangement is suitable, in particular, for hydraulic power steering systems of motor vehicles with a so-called closed center.

Abstract: A hydraulic jack movably supported by a plural casters has a vertically extending hydraulic cylinder with telescoping piston rods, has a load supporting frame at an upper end of the innermost piston rod, and has a reservoir partially filled with hydraulic fluid. A single foot pedal is pivotally supported on the jack, and is movable between first and second positions through a center position. A hydraulic valve arrangement is responsive to movement of the actuating member toward its first position for permitting fluid flow from the reservoir to the hydraulic cylinder and is responsive to movement of the actuating member toward its second position for permitting fluid flow from the hydraulic cylinder to the reservoir. A kicker lever supported for pivotal movement about the same axis as the actuating member is operatively coupled to the actuating member for movement therewith by two springs, and can actuate an air valve.

Abstract: The invention relates to a variable displacement pump supplying fluid to a number of consumers. The pump control for adjusting the delivery rate is actuated by a signal which is produced by the respective highest loaded consumer. The signal is provided by a valve, in particular a pressure compensating valve which is associated with the consumer, and which valve opens a spool land when the valve becomes positioned at its control end range. A pressure signal from any pressure fluid source is delivered through the land to the pump controller. The control, according to the invention, offers a broad variety of possibilities for arranging the pressure compensation valve at various locations, engaging the valve by a variety of pressure differences, and using a number of pressure fluid sources of provide for the signal pressure to actuate the pump controller.

Abstract: A metering valve adapted to operate a seat on a side of an actuator port by means of a poppet section of a main poppet arranged in a valve casing to selectively communicate the actuator port to a tank passage. The main poppet is formed with a pressure chamber on a side thereof opposite to the poppet section. The pressure chamber has a pressure receiving area substantially equal to that of the seat. Also, the main poppet is formed with a through-hole constantly communicated to the actuator port and a pilot chamber to which pilot pressure for moving the main poppet in a direction of opening the seat is applied. Thus, the metering valve is capable of stably accomplishing its control irrespective of a variation of pressure on the side of the actuator port.

Abstract: A hydraulic circuit for controlling the deck swiveling speed of a working vehicle comprises a hydraulic actuator for driving the swivel deck, a flow control valve for controlling a rate of oil flow to the hydraulic actuator, and a direction control valve for switching an operating direction of the hydraulic actuator. The flow control and direction control valves are operatively connected to a swivel control lever. The greater amount of swivel control lever is operated toward a right or left swivel position, to the greater extent the flow control valve is shifted in a flow increasing direction. The direction control valve is operable to switch oil lines in response to an operation of the swivel control lever.

Abstract: Presented is a fluid drive motor that may be attached to a conventional garden hose, for instance, to effect reciprocating motion of a drive shaft that may be connected to a utilitarian device, such as a scrub brush. The fluid drive motor is provided with a piston assembly that responds to the pressure of the fluid to translate the piston assembly from one position to another and in so doing imposes rotational reciprocation on a drive shaft that extends out of the motor block of the fluid drive motor. The reciprocating characteristics of the piston assembly are controlled by the imposition of fluid pressure, and the imposition of fluid pressure is controlled by a valve assembly cooperating with a reciprocable magnetic bar to channel fluid under pressure alternately to opposite ends of the piston assembly.

Abstract: The hydraulic piston cylinder assembly which operates the governor of a turbine which powers a hydropower generator has a servo valve capable of flowing only a portion of its flow requirements during normal low power fluctuation conditions of the turbine's operation. During high power fluctuation conditions of the turbine's operation, such as during start-up, hydraulic fluid also flows to and from the piston and cylinder assemblies through high flow pressure and return conduits that bypass the servo valve. Control of fluid flow in the high flow conduits is accomplished by a proportional throttling valve located in the high flow return line. The servo valve and proportional throttling valve together have a flow capacity which is equal to the flow requirements of the piston and cylinder assembly and they are both actuated by the same electronic controller.

Abstract: A time division multiplexed (TDM) hydraulic control system having a plurality of channels, each channel having a servo actuator. Electrical demand signals are arranged in TDM sequence and applied to a single multiplexed pilot valve so that the pilot valve produces a plurality of hydraulic signals. Commutator means are associated with the pilot valve for distributing the hydraulic signals to the associated channels. In order to achieve useful output flow rates in the channels, each channel includes a second stage valve which integrates the hydraulic signals for its channel to produce an output flow rate which is a function of the integrated signal. The flow rates are continuously produced (as compared to the multiplexed output signals) and are coupled to actuators in the channels for controllably adjusting the position thereof. Feedback means associated with the actuators includes rate feedback for stabilizing the multiplexed control loops.

Abstract: In a sensitive analytical instrument having an optical bench carried by a base member, new and improved vibration and shock isolation apparatus which includes three spaced pneumatic mounts interposed between the optical bench and the base member to provide vibration and shock isolation therebetween, each of the mounts having a preselected optimum linear range of operation, a source of pressurized gas, apparatus for individually controlling the inflation and deflation of each of the mounts with pressurized gas to maintain actual operation of each of the mounts within its preselected optimum linear operating range.

Abstract: The present invention provides a valve for controlling fluid flow. The tapered actuation surface of the actuation cam of the present invention controlled by electric motors may be utilized to gradually open and close the various pistons which regulate flow through the valve passageways. An actuation monitor acts to measure the amount of piston actuation so as to permit interactive control of the valve. One embodiment of the present invention may be utilized in response to signals received from an apparatus connected to a boom support member mounted on the back of the truck wherein it is desired to maintain the boom support apparatus in the substantially vertical direction.

Abstract: Adiabatic positive displacement gas cycle machinery is designed with explicit control of the heat flow between the gas and the walls. The control is achieved by maintaining near-laminar flow and a small wall area to volume ratio. The most stable near-laminar flow in a cylinder is an axial vortex because of symmetry, and hence the induction port design should establish an axial vortex and a low velocity. Induction and exhaust port designs to achieve this flow are applied to a vane pump, an adiabatic air compressor, a diesel engine, and two and four stroke Otto cycle engines. The gain in thermal efficiency for these designs can be significant, up to a factor of 2, since the largest inefficiency in nearly all positive displacement machinery is imperfect control of heat flow.

Abstract: An electro/pneumatic proportional valve having a housing defining an upper and lower chamber separated by an annular web. An inlet port and exhaust port concentric with the annular web are provided in said lower chamber while an outlet port is provided in the upper chamber. An exhaust cylinder is resiliently disposed through the exhaust port and has a radial flange engaging said annular web to occlude the annular web's central opening. The exhaust cylinder also has an axial bore passing therethrough and exiting through the exhaust port. A piston disposed in the upper chamber has a pintle which is operative to engage the exhaust cylinder with the displacement of the piston and occlude the exhaust cylinder's axial bore. Pilot valves are provided to pressurize the upper chamber in response to a pulse train signal displacing the piston towards the web. The displacement of the piston causes the pintle to engage the exhaust cylinder and unseat it from the annular web.

Abstract: A hydraulic pivot drive comprising a rotary-piston hydraulic cylinder and control device for maintaining the pressure difference between pressure chambers defined by the rotary vane and at least one radial wall of the cylinder housing required for maintaining a defined relative rotary position between the vane and the housing of the rotary piston hydraulic cylinder. The control a follow-up control valve, wherein the actual condition relative to the pivot angle is fed back via a measuring spindle coupled with the rotating part of the rotary piston hydraulic cylinder and the desired value is pre-set by rotation of a spindle nut engaging the spindle, an actuating member arranged for axial displacement together with the spindle nut and for actuating pairs of seat valves for enabling alternative connection of the at least two pressure chambers of the rotary-piston hydraulic cylinder with a system to obtain the desired rotation.

Abstract: The invention involves a new structure for a distributor for a hydraulic fluid utilization means, such as a single-acting jack, controlled by the distributor in any position. The distributor includes a spool-type valve and a hollow piston valve which is piloted by a needle valve. The needle valve and spool-type valve are both mechanically connected to a single mechanical lever.

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 and a variable displacement pump with loading sensing control for supplying fluid to said actuator. A pilot pressure operated meter-in valve is provided to which the fluid from the pump is supplied and pilot pressure is applied to the meter-in valve for controlling the direction and displacement of movement of the meter-in valve and the direction and velocity of the actuator. A pair of lines extends from the meter-in valve to the respective openings of the actuator and a pilot pressure operated meter-out valve is associated with each line of the actuator for controlling the flow out of the actuator when that line to the actuator does not have pressure from from the pump applied thereto.

Abstract: A pneumatic valve which is suitable for use in controlling the operation of a pneumatic drive system such as that used for raising and lowering the body of a dump truck. The valve is opened and closed by a slide member which is mounted in a cylinder fomed in the valve housing. An air inlet passage opens into the cylinder and an air outlet passage and a vent passage open from said cylinder. A first flow control valve in the inlet passage which is operable to close to prevent and open to permit the passage of air from the inlet passage to the cylinder. A second flow control valve in the vent passage which is operable to close to prevent and open to permit the passage of air from said cylinder to the vent passage thereby to vent the outlet passage.

Abstract: A hydraulically-operated breaking device of this invention uses a hydraulically-operated differential piston for driving an electric circuit switching unit, and making and breaking pilot valves for actuating the differential piston. In this device, a control valve operated by the action of the pilot valves includes two poppet valves, and drives an intermediate valve which drives the differential piston. Further, the control valve can perform a quick operation at breaking, and can accomplish a given operation even with use of impulse command signals to operate the pilot valves or even in case of a liquid pressure drop during the operation. Furthermore, the use of an auxiliary valve and an auxiliary switch provides the device with a simultaneous action preventive function, pumping action preventive function, and breaking operation preference function.

Abstract: A 3-port, 2-position, directional control valve has two cylindrical closure elements for the alternate connection of a control line to a return flow line and a high pressure line. The switching force exerted on a thrust member is transmitted via pressure pins, and a manifold member with a centrally-positioned axial bore connected to the control line is arranged between the closure elements. Sealing elements on the closure elements seal the exit openings of the bore in the manifold member alternately. One of the pressure pins extends through the manifold member eccentrically while extending parallel to the axial bore and is always under pressure, like the high-pressure-side closure element, so that the closure element on the low pressure side is always held open in the zero position of the valve while the closure element on the high pressure side is acted on by the pressure medium in the direction of closure.

Abstract: A fluid control valve fluidly connected between a source of fluid pressure and a fluid operated device for controlling the pressurization and depressurization of the fluid device. The control valve comprises an elongated housing having an inlet port and an outlet port formed at one axial end of the housing and an exhaust port formed at its other end. The inlet port is connected to the fluid pressure source while the outlet port is connected to the fluid device. A first fluid passageway formed in the housing fluidly connects the inlet port to the outlet port while, similarly, a second fluid passage in the housing fluidly connects the outlet port to the exhaust port. A first valve is disposed in the first fluid passageway and movable between an open and closed position while a second valve is disposed in the second fluid passageway and also movable between an open and closed position.

Abstract: A control system for controlling a double-acting cylinder includes four pilot-operated, proportional-type poppet valves for controlling fluid flow between the cylinder, a pump and a reservoir. Four solenoid-controlled pilot valves operate the poppet valves in response to error signals generated by a control circuit. The control circuit receives a cylinder position feedback signal and an operator-generated command signal. The control circuit provides for float, shutdown, variable deadband and pressure adjustment operation.

Abstract: A control system 54 for a doser type hydraulic actuator 56 is disclosed. The doser actuator includes a pair of unequal area pistons 18, 20 on a common shaft 16 which are moved incrementally by injecting into or removing from a control pressure chamber metered quantities or doses of fluid. The doses are metered by timed openings of solenoid valves 32, 34 connecting the control pressure chambered to a supply 44 or return 48 pressure sources. The control system includes a base pulse width signal generator 106 which pulse modulates the solenoids as a function of the error between a requested position and an actual position. The base pulse width is modified by a correction means 108, 110, 112 when the error is within a predetermined band width. The correcting means compensates for the reaction of the actuator when its response is uncertain with respect to the base pulse width.

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 system 54 for a doser type hydraulic actuator 56 is disclosed. The doser actuator includes a pair of unequal area pistons 18, 20 on a common shaft 16 which are moved incrementally by injecting into or removing from a control pressure chamber metered quantities or doses of fluid. The doses are metered by timed openings of solenoid valves 32, 34 connecting the control pressure chambered to a supply 44 or return 48 pressure sources. The control system includes a base pulse width signal generator 106 which pulse modulates the solenoids as a function of the error between a requested position and an actual position. The base pulse width is modified by a correction means 108, 110, 112 when the error is within a predetermined band width. The correcting means compensates for the variations of the actuator when its response is uncertain with respect to the base pulse width.

Abstract: A hydraulic rotation control circuit for a rotational actuator such as a hydraulic motor for rotating a rotary frame of a hydraulic crane, the circuit employing a combination of a number of check and variable reducing valves in a manner which allows smooth and delicate control of the rotation of the actuator to provide an operation performance equivalent to that of mechanical drive, including coasting operation of the motor.

Abstract: A hydraulic cylinder arrangement of the type wherein the opposite ends of a cylinder are connected selectively to either a pump or sump by a control valve. Each end of the cylinder is provided with a pair of oppositely acting, uni-directional check valves, each connected to a port on the control valve by an individual conduit. The four check valves are so arranged that all the fluid discharged from either end of the cylinder in response to the reciprocation of the piston therein is constrained to flow to sump before it is pressurized and returned to the cylinder.

Abstract: A 4-way, 2-position pilot valve having two ball valves seatable at approximately the same time without a precise spacing.

Abstract: The amount of axial movement of a plunger is controlled by a hydraulic servomechanism. The pressure in the hydraulic chamber of the servomechanism is controlled by opening and closing an inlet valve and outlet valve provided respectively at the inlet and outlet sides of the hydraulic chamber. When the difference value between the actual position and desired position of the plunger is greater than a first predetermined value, only one or the other of the inlet and outlet valves is energized. When the difference is intermediate the first predetermined value and a second predetermined value which is smaller than the former, the inlet and outlet valves are energized at different duty cycles. When the difference is smaller than the second predetermined value, the valves are both deenergized.

Abstract: A force balance instrument providing precision control of pneumatic actuators in response to command pressure signals independent of external forces on the actuator shaft. The instrument includes a high gain signal detection circuit in combination with one or two pilot operated output valves. In the case of two output valves inverse "push-pull" control of a double acting pneumatic actuator is provided. Full supply pressure differential can be developed across the piston of the actuator, permitting to minimize the size of the actuator for any specified output force.The positioner proper controls the position of valve actuator system through a stem connector arm and a feed-back spring. A force balance condition is initially established between the feedback spring and the force of a rolling diaphragm controlled piston assembly for the range of signal pressure P.sub.1 to be used. Any change in this force balance condition because of a change in signal pressure P.sub.

Abstract: A hydraulic amplifier comprising a housing wherein is defined a pressure chamber. A servo piston is slidable in a bore opening onto the pressure chamber. The amplifier also comprises a set of control valve connectible to a high pressure fluid source and a low pressure reservoir. An operator operated control rod has one end projecting into the chamber. In the pressure chamber is mounted a lever mechanism comprising a lever having one end pivoted on a pin associated with the housing, and the other end is moved by the control rod. The lever mechanism also comprises a rocker member which is pivoted on the lever and whose respective ends can bear on the servo piston and are adapted to move at least one valve in the control valve set. The pin is slidable relative to the housing and is urged by resilient means into an idle position. The control valve set comprises an exhaust valve operated by a rocker member, and a high pressure valve operated in response to the movement of the pin from its idle position.

Abstract: The invention relates to a hydraulic booster of the closed-center type and comprising a housing containing a working chamber, an actuating piston slidable in the working chamber, a set of a high-pressure valve and an exhaust valve of the ball valve type controlling fluid connections between an accumulator, the working chamber and an exhaust orifice. The high-pressure valve is controlled by a tappet including a sleeve having a central passage therein communicating with the working chamber and the exhaust orifice. The exhaust valve controls the fluid flow through the central passage. Both valves are actuated by movement of a sliding block adapted to engage the exhaust valve member.

Abstract: A fluid control valve assembly comprises a pair of identical valves mounted on a manifold with connections to the controlled actuator and to the high and low pressure sides of a fluid circuit incorporating a pump or other source of high-pressure fluid. Each valve includes a reciprocating tappet directly connected to a conical valve head and spring biased into a closed position of the valve, with a portion of the tappet protruding from the valve body. Superimposed on the two protruding tappets is a rocking beam which may be pivoted into contact with either tappet by means of a handwheel engaged in a bracket. A threaded shaft affixed to the handwheel passes through a nut pivotally secured to the rocking beam, so that rotation of the handwheel in either sense will result in the depression of one of the two valve tappets and the opening of the valve associated therewith.

Abstract: A control system for controlling a double-acting cylinder includes four pilot-operated, proportional-type poppet valves for controlling fluid flow between the cylinder, a pump and a reservoir. Four solenoid-controlled pilot valves operate the poppet valves in response to error signals generated by a control circuit. The control circuit receives a cylinder position feedback signal and an operator-generated command signal. The control circuit provides for float, shutdown, variable deadband and pressure adjustment operation.