Abstract: An actuator synchronization system comprising a control valve in fluid communication with a plurality of actuators; each of the actuators comprising an input member moveable by the control valve, a main valve moveable from a null to an off-null position, an output member moveable from a first to a second output position, and a feedback linkage and a drive link configured such that selective movement of the input member causes movement of the valve from the null to the off-null position and movement of the output member to the second output position causes movement of the valve member from the off-null to the null position; and a mechanical connector between each of the input members or drive links of the actuators configured such that rotational motion of each of the respective drive links is synchronized.

Abstract: Apparatus for providing mechanical feedback of a position of an actuator to a controller in a high vibration environment. The apparatus includes a member that contacts a cam surface of the actuator such that movement of the actuator and cam surface causes the member to move. The apparatus also includes a spring that exerts a force on the member toward the cam surface to maintain contact between the member and the cam surface. The apparatus also includes a damper that dampens motion of the member, thereby eliminating resonant movement of the spring and member caused by vibrations.

Abstract: A control program for a positive displacement metering system measures the time required for the travel of a free piston in a cylinder of known volume to determine an average flow rate during a full stroke of the piston. The system may also measure and record the inlet and outlet pressures or the differential pressure between the fluid inlet and outlet. The control program positions a four-way valve which may function as an adjustable metering orifice in response to the measured average flow rate and/or changes in the inlet and outlet pressures to achieve the desired flow rate. At the end of each stroke, the four-way valve is repositioned to reverse fluid flow through the metering cylinder. The system may revise the valve position settings for both forward and reverse strokes based on the measured time required for a full stroke at a certain valve position. In this way, the system automatically and iteratively compensates for changes in fluid properties and fluid pressure.

Abstract: An adjusting device of an axial piston machine having a displacement volume that is adjusted by a pivoting yoke. The adjusting device has a cylinder, which is radially spaced from and tangential to the yoke pivot axis. A piston communicates with the yoke and is adjusted by hydraulic pressure change. A control arrangement has a position regulating valve with a control piston which can set the hydraulic pressure acting on the piston. A mechanical return can transfer the yoke pivoting position to the control piston. The valve is axially parallel to the cylinder and radially spaced from the yoke pivot axis. The return comprises an axially movable sensing piston and coaxial return spring which are axially adjacent to the valve. The sensing piston abuts a yoke surface that is eccentric with respect to the pivot axis and connected to the control piston by the return spring.

Abstract: An apparatus is provided for exerting on a regulating piston of a control device a regulating force that is a function of the position of an actuating lever. The apparatus comprises a bearing arrangement for supporting the actuating lever, a first arm and a second arm, each of which is rotatably mounted on the bearing arrangement independently of the others. The apparatus additionally includes a carrier element that is connected to the actuating lever, and an elastic element connecting the first arm and the second arm to one another. The apparatus is especially distinguished by the fact that the position of the carrier element relative to the first arm and to the second arm is adjustable to establish freedom from backlash.

Abstract: The invention relates to a regulating device for hydrostatic piston machines consisting of an actuating piston (2) which can be removed between two end positions which can be impinged upon by actuating pressure exerted thereon in an opposite direction. An actuating pressure regulating valve (5) is used to regulate the actuating pressure. The actuating regulating valve (5), which is used to regulate the actuating pressure, comprises a regulating piston which can be shifted from a neutral position and which can be impinged upon with a regulating force which is dependent on the position of the actuating piston (2). The regulating force is directed counter to a control force acting upon the regulating piston (6) and the regulating force is zero when the regulating device (1) is in a rest position. When the regulating device (1) is in a rest position, the regulating piston (6) is in a neutral position and the actuating piston (2) is a specific end position.

Abstract: A servomechanism for a valve controlling engine intake flow via a cooler and a bypass uses a proportional solenoid operating a hydraulic valve to power a hydraulic actuator setting the position of the control valve. An engine sensor and electric controller provide input to the proportional solenoid, and feedback from the position of the control valve is applied to the hydraulic valve by a cam and spring applying a force in opposition to the proportional solenoid.

Abstract: A two-stage proportional control valve assembly regulates flow of a first fluid such as an engine exhaust gas using a second fluid such as engine oil for power. A directional valve under control of an electrical actuator regulates flows of the second fluid to operate a fluid-powered actuator. A mechanical connection between the fluid powered actuator and a flow control valve for regulating flows of the first fluid enables the electrical actuator to indirectly control the flow control valve with a minimum draw.

Abstract: A structure comprising firstly a differential sensor of linear displacement comprising a body and a core slidably mounted relative to said body, and secondly a rod of a servo-control actuator in which the core is mounted, said rod terminating in an endpiece which has a bore in which the core is received close to its end, said bore and the core having complementary threads which co-operate to hold said core relative to said bore, and means enabling the engagement of the core in said bore to be adjusted, wherein said means comprise an adjustment screw extending through the actuator rod and whose thread co-operates with complementary means carried by the core so that turning movement applied to the adjustment screw by an operator gives rise to axial displacement of the core in the bore of the endpiece.

Abstract: A feedback control system (i.e., a positioner) for precise positioning of a pneumatic actuator by adjusting the flow of air to the pneumatic actuator comprises an adjustable gain mechanism for adjusting the sensitivity of the positioner. The adjustable gain mechanism is coupled between a feedback input device of the positioner and a valve control device and is employed to adjust the amount of air supplied to the pneumatic actuator for a given displacement of the feedback input device. Preferably the adjustable gain mechanism is adjustable through a range of settings between a high gain setting and a low gain setting, the high gain setting allowing a greater range of motion of the valve control device than the low gain setting for a given displacement of the feedback input device.

Abstract: The present invention provides a servo-actuator capable of operating in both the Fail Safe and Fail Operate modes. In the Fail Safe mode, a pretensioned spring member moves a jet pipe in the servo-valve to cause said actuator rod to move in a first direction upon loss of electric power. A mechanical feedback means coupled to said spring member and said actuator rod opposes the force applied by the spring so that when a force equilibrium is reached the actuator rod will be at a predetermined position.

Abstract: The invention attenuates higher frequency vibrations or oscillations which can result in wear and/or less than optimal performance of a valve positioner. The invention provides a low pass mechanical filter which can be realized, for example, in a dash pot like damper device. The damper includes a pair of diaphragms associated with a pair of chambers, which are in communication with one another by an orifice. The chambers associated with each diaphragm are filled with oil or a hydraulic fluid such that the rate of relative motion (for example between a summing beam of the positioner and the location at which a signal force is applied) is controlled by flow of oil through the orifice.

Abstract: An electropneumatic positioner includes an electropneumatic converter, an pilot relay, an operating unit, and a sensor. The electropneumatic converter includes a yoke having central and side leg portions, a permanent magnet arranged on the central leg portion, a pair of coils for exciting the side leg portions to have opposite polarities, a nozzle embedded in one side leg portion to spray air having predetermined pressure, a stopper arranged on the other side leg portion, and a flapper arranged to be swingable on a fulcrum near the central leg portion and serving to change a nozzle back pressure by controlling the amount of air sprayed from the nozzle in accordance with a swing. The electropneumatic converter receives a duty signal, as a driving signal for the coils, which signal is obtained by converting a deviation between an input signal and a feedback signal into a duty. The flapper is set to be parallel to the yoke when the deviation between the input signal and the feedback signal is zero.

Abstract: A device capable of comparing the travel position of an output shaft of a diaphragm actuator or cylinder with the current level of an electronic input signal and further being capable of manipulating the pressure of a separate air signal piped to a diaphragm actuator or cylinder in order to correct any imbalance between such a shaft position and a given electronic signal level, including the ability of varying its dynamic response through built in adjustments.

Abstract: Position control for pneumatic positioning devices and the like, comprising a sensing lever linked to the drive rod of the positioning device and comprising a measuring lever acting on a measuring system, whereby the one lever is seated on a position control axle with positive lock or form-fit and the other lever is seated on said position control axle with non-positive lock, and comprising at least one detent acting on the measuring lever with which the sensing lever and the measuring lever are brought into an angle relative to one another that corresponds to a zero setting.

Abstract: A displacement controlled hydraulic proportional valve is provided with a dashpot disposed between a main valve spool and a pilot valve spool to stabilize the proportional valve. The dashpot includes a bore in a spring retainer engaging the main valve spool and a plunger axially extending from a spring retainer engaging the pilot valve spool with the plunger extending into the bore to define a dashpot chamber. The plunger is sized to permit restricted fluid flow thereby when the spools move relative to each other thereby dampening relative movement between the valve spools. Dampening the relative movement between the valve spools drastically reduces the amount of overshoot by the main valve spool.

Abstract: A displacement controlled hydraulic proportional valve has a spring retainer and a force feedback spring serially disposed between a pilot valve spool and a main valve spool in a control chamber. An arcuate convex end portion on the pilot valve spool extends into a cylindrical pocket in the spring retainer essentially defining a contact point through which force is transferred between the pilot valve spool and the retainer. The point contact minimizes side loading on the pilot valve spool due to buckling of the feedback spring to minimize tendency of the pilot valve spool to stick during operation.

Abstract: A valve positioner has a pneumatic transducer responsive to a signal pressure for displacing a spool valve away from a neutral position to effect actuation of an actuator output shaft and further includes a gain adjustment apparatus. The pneumatic transducer includes a balance beam being operably connected at one end to the spool valve and at the other end to a hinge spring. A clamp mechanism is attached to the hinge spring and is slidably adjustable along the length of the hinge spring to vary the spring characteristics. The hinge spring tapers in thickness such that the spring increases in thickness in a direction from a first end of the spring towards the balance beam. A window or cut-out is also provided in the hinge spring to further assist in varying the spring characteristics as the clamp mechanism is moved along the hinge spring, and provide a wide range of gain adjustment over the single spring.

Abstract: A device for converting an electric current signal into a mechanical correcting variable, includes a pneumatic correcting element (1) with slide rod (2), a pneumatic amplifier (3), a compressed-air supply (4) and an electropneumatic signal converter which has a solenoid (5) with coil, iron circuit and air gap, a nozzle/baffle-plate device (6), and a lever (8) which is swingably mounted on a tensioning band (7). One end of the tensioning band (7) is mounted for turning around its longitudinal axis and, perpendicular to the longitudinal axis there is arranged a feedback lever (12) one end of which is attached, fixed in rotation, to the turnable end of the fastening belt (7) while its free end is coupled to the slide rod (2) of the pneumatic correcting element (1).

Abstract: A displacement control valve has a valve body with a fluid metering valve spool axially movable between pilot pressure chambers formed at opposite ends of an interior bore in the valve body. An internal spring feedback apparatus is mounted on the valve spool in one of the pilot pressure chambers and elastically interconnects the swashplate of a variable displacement hydraulic unit with the valve spool. An elongated housing surrounds the spring and spring guides and is mechanically coupled with the swashplate. The housing and spring guides form a fluid seal between the valve spool and the valve body to seal the pilot pressure chamber in which the feedback apparatus is mounted.

Abstract: A control force input system for a balance beam pneumatic valve positioner which does not allow the controlled apparatus to make a full travel motion when the overall control signal is removed. The control force is transmitted to the balance beam or other force summing bar using a linear solenoid coupled to a control spring coupled to the balance beam. When the motive power control signal is removed from the linear solenoid, the balance beam establishes an equilibrium position based on the existing position of the linear solenoid. Split wedges are repelled from the linear solenoid when a control signal is applied, releasing the solenoid shaft for movement. Alternatively, split slides are repelled from each other when a control signal is applied, releasing the solenoid shaft bias spring. When the control signal is removed, the split wedges or split slides are biased and attracted to the solenoid, locking the solenoid shaft in position. A variation for use with a current to pressure transducer is detailed.

Abstract: A control force input system for a balance beam pneumatic valve positioner which does not allow the controlled apparatus to make a full travel motion when the overall control signal is removed. The control force is transmitted to the balance beam or other force summing bar using a linear solenoid coupled to a control spring coupled to the balance beam. When the motive power control signal is removed from the linear solenoid, the balance beam establishes an equilibrium position based on the existing position of the linear solenoid. The solenoid shaft extends into a captive cylinder. A piston connected to the solenoid shaft is located in the captive cylinder and forms two chambers in the cylinder. A solenoid valve connects a port in each chamber. When the solenoid valve is activated, the piston is free to travel. When the solenoid valve is deactivated, as when the control signal is removed, the piston is held in position, locking the solenoid shaft in position.

Abstract: The main control piston (8) is controlled hydraulically by pilot control slide valves, operated in each case via two control magnets (4, 6) with force build-up proportional to the control current. In the case of failure of the electrical activation, the valve is always positioned in the center position by pressure centering and in the case of failure of the pilot control pressure it is positioned in the center position by spring centering.

Abstract: A hydraulic sensor and pressure transducing apparatus is disclosed which is characterized by the use of a biased piston and valve element arrangement to translate the displacement of an actuator to provide a pressure signal proportional to the displacement being sensed. The piston is mounted in a bore provided with inlet and outlet ports. A valve element is positioned in the bore in an opposing resiliently biased relationship to the piston in communication between the inlet and outlet ports. A constant selected hydraulic flow is fed into the bore inlet through the valve element and out of the bore outlet port to develop a pressure on the inlet port side which is proportionally to the displacement of the piston as reflected by the biased force exerted against the valve element. An actuator is linked to the piston by a cam surface in a manner that permits the angular position of the cam operating on the piston to be reflected as a proportional pressure on the inlet side of the valve element.

Abstract: A pneumatic control valve comprises a position controller and a valve which is influenced by the controller. A valve member can be lifted by means of a servomotor which is securely connected to the valve housing by means of a yoke, the servomotor being connected to the valve member by means of a valve rod. The lift position of the valve rod is sensed by means of a rotatable lever of the position controller, which rotatable lever is in a working connection with the valve rod by means of an articulated device. A housing encloses the valve rod, the lever and the articulated device.

Abstract: A pneumatic control valve comprises a position controller and a valve which is influenced by the controller. A valve member can be lifted by means of a servomotor which is securely connected to the valve housing by means of a yoke, the servomotor being connected to the valve member by means of a valve rod. The lift position of the valve rod is sensed by means of a rotatable lever of the position controller, which rotatable lever is in a working connection with the valve rod by means of an articulated device. A housing encloses the valve rod, the lever and the articulated device.

Abstract: A valve positioning device capable of comparing the travel position of an output shaft of a diaphragm actuator or cylinder with the pressure level of a pneumatic input signal and further being capable of manipulating the pressure of a separate air signal piped to said diaphragm actuator or cylinder in order to correct any imbalance between said stem position and a given pneumatic signal level; wherein said valve positioning device is further capable of varying its dynamic response by built in adjustment means.

Abstract: A direct drive servo valve includes a housing and a series of conduits connecting the housing to a fluid pressure source and to an associated actuator, a sleeve in the housing having a plurality of passageways interconnecting the conduits and a spool valve member rotatable within the sleeve to connect the conduits as desired, the spool valve being rotated by a torque motor. The torque motor rotor is connected to the return side of the fluid pressure source. The sleeve is formed of a series of disks which have a desired pattern of holes therethrough and which are bonded together to create a manifold structure having the desired pattern of passageways. A rotary variable differential transformer is connected to the spool and provides feedback signals to an external circuit controlling the torque motor. A torque rod is connected to the spool and the housing to provide a preload which tends to center or "null out" the spool position when there is no input signal.

Abstract: A control force input system for a balance beam pneumatic valve positioner which does not allow the controlled apparatus to make a full travel motion when the overall control signal is removed. The control force is transmitted to the balance beam or other force summing bar using a motor coupled to a drive unit which compresses or extends a control spring coupled to the balance beam. When the motive power control signal is removed from the motor, the balance beam establishes an equilibrium position based on the existing position of the motor.

Abstract: A fluid powered actuator system includes two identical fluid powered actuators operable by respective supply pressures which are controlled by respective identical valve arrangements. Operating positions of flow control elements of the valve arrangements are applied through respective couplings to a differential arrangement which operates, if these positions differ by an unacceptable amount, to apply an error indication through respective coupling to prevent the supply pressures from being applied to the respective actuators.

Abstract: The booster comprises a first member (23) positioning the plunger (14) and fastened in the valve body (8) and interacting with a the first zone of a shoulder (21) of the plunger to position the latter in a specific position of maximum retraction relative to the valve body (8), and a second member (29, 31) positioning the plunger and mounted pivotally in the valve body and having a ramp surface (34) formed in a first portion (29) interacting with a second zone of the first shoulder (21) to position the plunger in a specific position of rest relative to the valve body (8) under the control of a second outer portion (31) interacting with a stationary element connected to the housing (9).

Abstract: An actuator for moving a valve or other controlled part in correspondence with variations in an input signal and including a piston movable in opposite directions within a cylinder and having a smaller effective area exposed to fluid in a first chamber at one side of the piston than to fluid in a second chamber at the opposite side of the piston, a pressure fluid source delivering pressurized fluid to the first of these chambers and delivering pressurized fluid to the second chamber through a three way valve having a body containing inlet and outlet openings and a valve element movable relative thereto in a manner varying the pressure delivered to the second chamber of the cylinder.

Abstract: A remote control proportional flow adhesive dispensing gun is pneumatically actuated and electrically controlled. An electric current applied to a magnetic torquemotor rotates a torquemotor arm which displaces the spool of a three-way air valve, admitting air to a control valve stem actuating piston. A constant rate feedback spring directly disposed between the actuating piston and the torque arm of the torquemotor acts to restore the air valve spool to an equilibrium non-flow position as the control valve stem approaches a position proportional to torquemotor control current. The air valve exhausts air from the piston and return springs close the control valve when control signal is removed. A shaped control plug attached to the flow control valve stem varies a control opening linearly as stem position changes.

Abstract: An axial bore which extends through the spool and receives a control rod. Channels formed in the control rod cooperate with radial passageways in the valve spool. A pair of torsion rods extend axially from the control rod. One is coupled to a stepping or torque motor, the other is coupled to a rotatable drive member. An assembly for converting axial motion to rotary motion couples the valve spool to the drive member. In the preferred embodiment, this assembly takes the form of a rotatable threaded member secured to the end of the torsion rod and receiving a complementarily threaded end portion of the valve spool. One alternate embodiment comprises a pair of threaded rods extending from the spool, which drives a centrally disposed gear through a pair of complementarily threaded pinion gears. In another alternate embodiment a pressure control valve is achieved. Output fluid from the spool valve is applied to opposite sides of a threaded piston, which is spring biased by opposed compression springs.

Abstract: In a pneumatic position controller for controlling the position of a pneumatic servomotor (10) to a value determined by a pneumatic command pressure, the command pressure acts through a movable wall member (30) on a pivotable balancing member (40). The balancing member (40) controls through a baffle plate (52) the outlet nozzle (56) of a pneumatic amplifier (24). The balancing member (40) is axially spaced from a feedback lever (44), with aligned pivot axes. A helical torsion spring (50) has one end attached to the balancing member (40) and the other end attached to the feedback lever (44). The feedback lever (44) is rotatable by the servomotor (10). An advantageous and compact construction permitted by the use of the helical torsion spring (50) is described.

Abstract: A servovalve includes a flow-control valve connectable between a source of fluid pressure and a load and having a spool displaceable between an open position permitting fluid flow between the load and the source and a closed position axially offset therefrom and blocking such flow. A pilot valve has an impact plate and a pair of nozzles operatively axially oppositely effective on the spool and oppositely flanking the plate. Thus when the plate is closer to one of the nozzles than to the other the spool is axially displaced into one of its positions and when the plate is closer to the other nozzle the spool is urged axially oppositely. A solenoid-type servomotor is connected to the impact plate to move same between the nozzles so that when it is close to one nozzle it blocks flow therefrom and allows pressure to build up on the corresponding end of the spool, while the other nozzle is opened to reduce pressure at the corresponding spool end.

Abstract: The invention is directed to a process for establishing a coupling with adjustable reduction ratio between a first driving rotation motion (r1) around a first fixed axis (10) and a receiving translation motion. The invention is also directed to a coupling device (1) that activates the receiving translation motion (f2) by mechanically coupling it with a second rotation motion (r2), called receiving motion, around a fixed axis (21) and establishing an adjustable mechanical correlation between the said driving (r1) and receiving (r2) rotation motions.The invention refers also to apparatus for the regulation of the amplitude of a parameter, and more particularly to valves (30) for the regulation of the flow rate of a fluid, whose nominal flow rate factor is steplessly adjustable, and which uses the abovedefined process and coupling device.

Abstract: An electro dynamic set device including an output set element, a piston having a piston rod and operable against the action of a force of hydraulic pressure and means defining a valve passage which communicates with an operating side of the piston to which hydraulic pressure is supplied. The passage is opened and closed by a control slide which operates by an electromagnet that can apply a magnetic force. A spring acts between the control slide and the piston such that the spring tends to move the control slide against the action of the magnetic force in a direction closing the passage. The control slide is annular and concentric around the piston rod and is located together with a coil of the electromagnet and an associated armature thereof in a common chamber. The coil encircles the piston rod as does the slide. The operating side of the piston is in the common chamber, the armature being suspended by another spring which permits movement of the armature in the length direction of the control slide.

Abstract: A force transmitting fluid actuator for use with a control device wherein an actuator member, movable within an actuator housing, actuates the control device due to the urging force of a plurality of pistons which can be selectively pressurized in unitary increments. The plurality of pistons are disposed within pressure chambers formed in the actuator housing in a symmetrical ring-shaped arrangement concentric to a single pressure chamber disposed on the vertical axis of the housing. A number of passageways interconnect the plurality of pressure chambers to form groupings of pressure chambers which act simultaneously in response to operation of a solenoid valve associated with each passageway. In addition to the symmetrical arrangement of the pressure chambers, the valve and passageway arrangement provide for a symmetric pressurization of the pressure chambers thereby resulting in a balanced force being exerted on the actuator.

Abstract: A power assistance device has a double acting piston and cylinder whose piston rod is connected to an output. Compressed air is passed via a pair of air pressure regulators to opposite sides of the piston. Each regulator has a regulator spring, and the regulators are housed in a body which is moved upon manual effort being applied to an input to cause the springs to differentially bias so decreasing pressure on one side of the piston and increasing pressure on its opposite side, creating a pressure differential across the piston causing it to move with its piston rod to apply a magnified load to the output which is proportional to the manual effort applied to the input. The regulators could be set so that in a neutral position of the power assistance device, zero pressures exist on opposite sides of the piston. In an alternative arrangement a pair of single acting piston and cylinder devices could be used.

Abstract: A positioner-actuator control system includes a pair of relays and a pivotally mounted beam for operation thereof in response to a pneumatic control signal. A summing beam has forces applied to it from an input signal, a controlled device position lever, a zero adjustment and a damping mechanism comprising a pair of flat springs attached to the relay beam and to the summing beam. A clamp is movable along the flat springs to permit user adjustment of the damping force.

Abstract: An electrohydraulic set device includes, as an output element, a piston which is operable by a hydraulic pressure against the action of a return force. The hydraulic pressure is led to the working side of the piston via a valve passage. The valve passage is opened and closed by an electromagnet operated control slide. The control slide is arranged along a piston rod connected to the piston together with a coil of the electromagnet, the armature being arranged therebetween, in a common chamber, of which the working side of the piston forms part. A spring force between the control slide and the piston tends to move the slide against the action of the magnetic force in a direction closing the passage. The control slide lies to the side of the piston.

Abstract: A two-stage pneumatic servo valve assembly for controlling an output motor is disclosed. An input device, such as a torque motor, is coupled to the two-stage servo valve assembly. The first stage of the servo valve assembly includes a vane valve movable by the output of the torque motor to selectively provide a fluid path from an input source to one of the first-stage output channels. The first-stage pneumatic servo valve is coupled with a second stage servo valve. The second stage servo valve controls fluid flow from a pneumatic fluid source to an output motor. The second stage servo valve includes a slidable spool valve movable by fluid received from the first-stage servo valve. A feedback control from the second-stage servo valve to the first-stage servo valve is provided. A second feedback control is provided from the output of the output motor to the first stage servo valve.

Abstract: An adjusting mechanism (92) is provided between a valve spool (62) and a valve actuating lever (26) whereby with the lever (26) locked in a selected position, the mechanism (92) is manipulated to move an element (99) carried by the valve spool (62) into alignment with an indicator (110) that has been predetermined to be the selected setting of the valve. With the element (99) aligned with the indicator (110), the mechanism (92) is locked so that the valve spool (62) is in the selected setting when the lever (26) is in the selected position. A lock-down apparatus (70) is provided for use in locking the lever (26) in the selected position while the adjusting mechanism (92) is being manipulated.

Abstract: A fail-fixed electrohydraulic servosystem in which a variation from a predetermined range of electrical input to the servosystem results in the output of the system being fixed in position. Fixing-in-position is accomplished by either hydraulically or mechanically locking a linkage to the output arm of the servosystem. Provision is also made for controlled drift and manual adjustment of the output after it is fixed in position.

Abstract: Single annular membrane type of pneumatic positioner associated with a servo control comprising a cylinder-piston assembly, feedback connected to the positioner, which includes a hollow body, internally of which there is provided at one side a reverse feedback spring controlled by the servo control, and at the other side a slide or distributing valve is provided, the inner cavity of the pneumatic positioner being separated by a single annular membrane, capable of being displaced under the action of an adjusting signal, said annular membrane being provided at the center with a hole through which a stem of the slide or distributing valve frictionessly slides, which stem bears against a dish-like member resting on the reverse feedback spring, while at the opposite side the slide or distributing valve bears on a low load spring.

Abstract: A flapper valve having a negative rate characteristic is variably opened by an external force and controls fluid pressure to a piston which moves, in response to this pressure, in order to return the valve to a null position. A positive rate flapper valve applies force to the negative rate flapper valve and balances the fluid pressure in the negative rate flapper valve, thus providing high sensitivity negative flapper valve operation in the null position region and a negative rate in the region to overcome piston friction, without instability.

Abstract: A fluid control system includes a fluid motor 11, a control valve 12 for directing fluid flow to and from the motor 11, and a control valve actuator 14 for operating the control valve 12. The control valve actuator 14 includes an actuator member 32, a feedback member 44, and a spring 46 which exerts a force on the actuator member 32 whose magnitude varies with the relative positions of the actuator member 32 and the feedback member 44. A command pressure signal moves the actuator member 32 to operate the control valve 12 in order to direct fluid flow to and from the fluid motor 11. A feedback link 41 connects the feedback member 44 to the fluid motor 11. The actuator piston 32 is slidably carried on the feedback member 44, so that any drifting of the fluid motor 11 results in immediate movement of the actuator member 32 and control valve 12 to correct the drifting.

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

Abstract: In the case of a pressure-worked automatic control system with a closed loop, and, more specially, a position automatic control system, the position of a servo-element is dependent on a spring placed between the servo-element or servo-motor and the sensing unit of the position automatic control system. The spring, placed between the servo-element or servo-motor and the sensing unit of the position automatic control system, is made up of at least one spiral spring, whose one end is able to be turned by a moving servo-part of the servo-element or servo-motor, while its other end is designed for acting on the sensing unit of the position automatic control system.