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

Abstract: A thermostat construction having a valve unit for directing a pneumatic signal to a pneumatically operated control device in relation to the force differential between the temperature sensed by the temperature sensing unit thereof and the temperature setting of a temperature setting unit thereof, a lever being pivotally mounted to the construction and being operatively interconnected to the valve unit at a first portion of the lever and to the temperature setting unit and the temperature sensing unit at a second portion of the lever.

Abstract: A servo mechanism for adjusting the position of a biased control member of a sliding ring for controlling pressure fluid in a main conduit of a hydraulic machine, comprises a manually adjustable sleeve, a setting piston arranged for reciprocating movement in the sleeve and being hydraulically connected thereto to resume a position preset by the sleeve, a follower piston coupled between the setting piston and the biased control member of the recoiling device, a control pressure space provided above the follower piston, a unidirectional first control conduit delivering a regulating stream of pressure fluid from the main conduit to actuate the setting piston, a second control conduit between the main conduit and the pressure space, and a flow controlling valve controlled by pressure in the first control conduit for equalizing pressure between the pressure space and the main conduit thus allowing override of the setting piston during the pressure setting operation.

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: An improvement in a servovalve employing spool-valve-position feedback provided by a feedback spring, wherein the feedback spring centerline is not aligned vertically with the center line of the spool valve, comprising a receiving hole in the spool valve body and a slot in the spool for feedback spring clearance; a pin or ball rigidly attached to the feedback spring with the portions of the pin or the ball which contact the sides of the receiving hole fitting in face to face relation to the inner surface of recesses formed in the slot by the hole.

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

Abstract: A method of making a pneumatically operated actuator having a pneumatically operated movable wall interconnected by a feedback tension spring to a pilot valve positioner that is adapted to pneumatically operate the movable wall of the actuator in relation to a pneumatic signal directed to the positioner, the method including the steps of loosely projecting one end of the spring through an opening in the wall after the other end of the spring has been interconnected to the pilot valve positioner and pulling on the one end of the spring while directing a predetermined pneumatic signal to the positioner so that the wall will assume a position thereof relative to the one end of the spring and the actuator that corresponds to the predetermined pneumatic signal whereby the one end of the spring can be secured to the wall while the wall is in that position thereof and the spring is in the pulled condition thereof that caused the wall to move to such position.

Abstract: The instant invention relates to an electrically operated control which operates the displacement setting mechanism of a variable displacement pump and allows the displacement mechanism to be manually operated when the electrically operated control is disabled.

Abstract: A pneumatic valve actuator having a rotatable output shaft is provided with a valve positioner comprising an axially displaceable spool valve and a pneumatic transducer responsive to applied signal air pressure for displacing the spool valve away from a neutral position to effect rotation of the actuator output shaft. The actuator output shaft is gear-connected to an element which rotates with the output shaft, and an elongated cantilever beam spring attached at one end to the rotatable element extends in a direction transverse to the axis of rotation of said element to the transducer for providing a feedback force which balances the control signal responsive transducer force when the actuator output shaft has rotated to a desired position.

Abstract: Fuel dispensing apparatus for dispensing fuel to a gas turbine engine is provided which includes a fuel metering slide valve having a control slide piston which directly controls an opening for supply of fuel to a gas turbine engine. A piston-cylinder servo-mechanism is provided for controlling flow of a servo fluid which acts on the control slide piston to assist in the movement thereof between respective positions. An auxiliary control slide piston of the servo-mechanism is in turn acted upon by supply of pressure to respective oppositely facing pressure surfaces from an electro-hydraulic converter. The electro-hydraulic converter is controlled by an electronic control mechanism responsive to control an engine operating parameters.

Abstract: An electrohydraulic servovalve including a second stage piston slidably mounted within a housing and movable responsive to application of pressure signals thereacross to control the flow of fluid under pressure from a source to a load in response to electrical input signals applied to the servovalve. The electrical signals are applied to a torque motor which has a driven member affixed thereto which generates the pressure signals applied to the spool. A mechanical feedback member is connected between the driven member and the spool. The mechanical feedback member is part of an assembly which is removably attached to the driven member. The removable attachment includes a tang extending radially from the driven member which receives a holder to which the feedback member is permanently affixed. The holder includes opposed flanges one of which receives the tang through an indexing opening provided therein.

Abstract: A conventional control valve hydraulically powered by a double acting cylinder and controlled electrically through a double acting solenoid supplied by a variable D.C. supply. The solenoid transmits varying forces to a four-way pilot valve which in turn controls the positioning of the double acting cylinder. The de-energized solenoid, control valve spool and pilot spool are neutrally balanced between two springs equally loaded with differing spring rates so that a small movement of the solenoid core will cause a proportionally larger movement of the main control valve spool proportioned to the different spring rates.

Abstract: A method of making a pneumatically operated actuator having a pneumatically operated movable wall interconnected by a feedback tension spring to a pilot valve positioner that is adapted to pneumatically operate the movable wall of the actuator in relation to a pneumatic signal directed to the positioner, the method including the steps of loosely projecting one end of the spring through an opening in the wall after the other end of the spring has been interconnected to the pilot valve positioner and pulling on the one end of the spring while directing a predetermined pneumatic signal to the positioner so that the wall will assume a position thereof relative to the one end of the spring and the actuator that corresponds to the predetermined pneumatic signal whereby the one end of the spring can be secured to the wall while the wall is in that position thereof and the spring is in the pulled condition thereof that caused the wall to move to such position.

Abstract: A pilot operated valve positioner having a pilot valve unit operated by a pneumatic signal to pneumatically operate an actuator unit carrying a main valve member to position the same relative to its main valve seat in a valve unit in relation to the magnitude of the pneumatic signal, the actuator unit having a range spring and a feedback spring for the pilot valve unit. The springs are coiled compression springs and are substantially concentrically mounted. The pilot valve unit has a feedback positioning diaphragm and part of its housing concentrically disposed in one end of the range spring to render the valve positioner relatively small and compact.

Abstract: An electrohydraulic servo system to actuate the power shaft of a fuel control system from the cockpit throttle including electrical devices responsive to the position of the throttle that actuates a hydraulic piston for moving the power shaft together with a backup system that assures a shaft position proportional to the throttle position. This permits the use of electrical lines from the cockpit to the engine rather than mechanical cables and linkages.

Abstract: A fluid pressure operable servo positioner for selectively positioning a mechanical member or lever by a power cylinder selectively positionable in accordance with the degree of operating fluid pressure supplied thereto through a control valve device at a pressure determined by the degree of a selectively variable control pressure supplied to the control valve device, the power cylinder including a counteracting spring for balancing the force of the operating pressure to maintain the power cylinder in the selected position and a cam member engaging the control valve device and positionable according to the position of the power cylinder for maintaining the control valve device in the selected pressure supply position.

Abstract: A cable is connected between the dump body of a dump truck and the movable control member of an hydraulic valve to automatically shift the valve from its "raise" position to its "neutral" position when the dump body approaches its uppermost raised position. There is means to prevent inadvertent transmission of forces from the cable to the movable control member to thereby prevent accidental lowering of the dump body due to an inadvertent pull on the cable.

Abstract: A positioner for a fluid-operated actuator has a fluid control valve displaced by a controlling force applied to a force-balance lever engaging one end of a biasing spring, the other end of which engages feedback means including an element displaceable by actuator movement. The valve lies between the biasing means and said feedback means element. Adjustment means are provided for the spring and for the feedback means to set the actuator zero position and movement range. Fluid conduits from the valve comprise open channels in a unitary member containing the valve and with a wall of a housing form closed section passages to porting in said wall opening directly into the actuator porting.

Abstract: A hydromechanical servo system having mechanical feedback is stabilized by damping the control valve and providing limited motion yieldable means for allowing limited yielding movement of feedback means relative to biasing means which biases such feedback means to a passive position.

Abstract: A mechanical feedback controlled valve regulates the fluid flow into the vane or piston compartment for controlling the direction, position, velocity, acceleration and/or deceleration of the output shaft.