Abstract: A pneumatic control assembly for a pneumatic cylinder having cylinder ports at the opposite ends thereof wherein the control assembly includes a valve body clamped directly to the pneumatic cylinder by a stud extending completely through the valve body and threadedly engaging the bore in the cylinder to provide the only means for maintaining the valve body attached to the pneumatic cylinder. An identical stud extends through an adapter to engage the other port in the cylinder and a pilot body is connected to the valve body by screws and includes electrically actuated solenoids for conducting pilot pressure to the valve body for allowing the full pressure to enter and exhaust from the respective ports in the cylinder to move the piston therein back and forth.

Abstract: An improved right angle drill including a pneumatically powered motor and feed and retract apparatus driven by the motor. The feed and retract apparatus includes a control valve for controlling the flow of pressurized air to the motor and to the feed and retract apparatus to automatically stop the feed motion, to automatically stop the retract motion, and to stop the drill completely.

Abstract: A hydraulic control apparatus has at least two meter-in and two meter-out poppet valves. In order to be compact and deal with a great flow rate, the apparatus is arranged such that a pair of meter-in poppet valves and load check valves are located in an upper horizontal plane, a pair of meter-out poppet valves and solenoid-actuated pilot valves are located in a lower horizontal plane, and a pair of a pilot valve associated with the meter-out poppet valve and a reducing valve associated with the meter-in poppet valve are located in a middle horizontal plane and are respectively disposed in opposed relationship to each other, and the load check valve is vertically located in parallel relationship with the meter-out poppet valve.

Abstract: A known power steering system of the type in which movement of a steering wheel is transmitted via a torsion bar to an oil path switching valve to actuate a power cylinder in a desired steering direction by switching a high pressure oil pump to the oil path switching valve and a low pressure oil path extending from the oil path switching valve to an oil tank and a part of working oil flowing through the high pressure oil path is led to a reaction piston to restrain torsion of the torsion bar, is improved by providing a main orifice disposed in the high pressure oil path and a control oil path branched from the upstream side of the main orifice in the high pressure oil path and communicating with the reaction piston. A pressure control valve is interposed in the control oil path for controlling the oil pressure so as to be equal to or lower than a predetermined highest pressure, and a bypass is provided for bypassing the upstream side and the downstream side of the main orifice.

Abstract: A flow and pressure control valve system is provided in which a control valve body 18 has a bore 22 therein with a slidable piston 24, the piston being biased to the left by spring 32 to a stop 38, with ports 16 and 26 opening to the bore 22 in the pressure end portion of the bore, the port 16 being connected to a positive displacement pump 28 and the port 26 connected to a reservoir 30 through a two-way valve, a third port 40 being connected to an actuatable device 10 and a fourth port 42 being connected to the reservoir 30 and functioning as a pressure regulator port after the two-way valve 28 is closed, and the piston 24 is retracted to the right as in FIG. 2 so that the device 10 is first actuated, and the pressure is then regulated by the relation of the piston 24 to the pressure regulator port 42.

Abstract: A speed limiting hydraulic slide valve. The slide valve is provided with control pressure chambers at each end thereof. The slide is provided with a longitudinal passage at each end and this passage opens into the adjacent control pressure chamber. Each passage is normally closed by a check valve. Each longitudinal passage communicates with a peripheral passage on the valve of the slide by means of a radial passage. If the hydraulic actuator, such as a cylinder, begins to move too rapidly, the pressure in the radial passage will drop, and the pressure in the appropriate control pressure chamber will thereupon overcome the check valve in the passage which opens into such chamber, and this will cause the valve slide to move in a direction which will decelerate the action of the cylinder.

Abstract: A device for controlling an adjustable arm 1 has an operating circuit 10 including a movable valve 3 with two control mechanisms 11, 12 bidirectionally actuated by pressure. A control circuit to activate the movable valve is connected to a pressure source 19, to the two control mechanism 11, 12, and to an adjustable throttle 22 attached to one of the two control mechanism 12. The control circuit also includes an adjustable throttle 24, series connected adjustable throttles 27, 28 attached to the other control mechanism 11 and a fifth adjustable throttle 57. The fifth throttle is used to create an additional actual value input. An adjustable control valve 53 employs the desired and actual value inputs supplied by the adjustable throttles in various ways by interconnecting the throttles with the control devices and a pressure ratio valve 45 so that the system responds to applied force, position or both.

Abstract: An electrohydraulic compact drive for turbomachine valves includes: a device for supplying electric power, receiving electrical addressing signals and converting the signals into positioning and control variables; an hydraulic supply system including a fluid tank, pump, motor, accumulator and manifold; an hydraulic power piston/cylinder system including a piston rod connected to a valve, and a spring biasing the piston; an electrohydraulic addressing system generating a pressurized fluid flow opening the valve spindle against the spring dependent upon the variables; control members of the addressing system, the power system and the supply system forming a compact drive block at a valve; the pump being switched as a function of a pressure limit by intermittent charging and discharging operations between the charging pressures; the pump charging the accumulator in charging operation until the upper pressure is reached and, after being switched, returning the fluid to the tank in substantially pressureless circu

Abstract: A hydraulic circuit arrangement for controlling a plurality of actuators connected to a high pressure line of a main pump parallel to each other has a sequence valve interposed in a line bypassing from the high pressure line to a reservoir. In the bypass line a throttle is interposed between the sequence valve and the reservoir. A regulator for controlling the displacement of the main pump is connected to the bypass line between the sequence valve and the throttle at a pilot chamber thereof. An auxilially pump is connected to the high pressure line parallel with the sequence valve. A delivery line of the auxilially pump has a bypass line interposed with a relief valve. The main pump may be switched to unloaded condition for the stand-by condition of the actuators and to loaded condition for the operation condition of the actuators.

Abstract: An apparatus for controlling the movement of a movable element as a working circuit (10) with a directional control valve (3) equipped to control devices (11, 12) which can be pressure activated in two directions. A control circuit (29) which can be connected to a fluid source (19) is used to activate the directional control valve for which the control circuit is connected to the two control devices and has an adjustable first choke (24) connected to one of the two control devices (12), a second choke (22) which is similarly adjustable and connectable to the same control device, and third and fourth adjustable chokes (27, 28) which are connectable to the other of the two control devices (11). The first and third chokes are connectable further to a storage tank (7) and the second and fourth chokes are further connectable to a pressure source. A proportioning pressure valve (45) can be connected to the other of the two control devices (11). The first and third chokes are connected to a pilot valve (38).

Abstract: A cylinder driving apparatus, wherein a head chamber and a rod chamber of a cylinder for driving a load upwardly and downwardly are communicated with a pressure accumulation tank by way of a balance pipeway equipped with an electromagnetic proportional flow control valve and a recycling pipeway equipped with a pressure control valve mechanism, respectively, and the load is driven by feeding air at reduced pressure to the rod chamber or discharging it to the external atmosphere by way of the pressure control valve mechanism while applying air pressure into the head chamber of the cylinder against the load by way of the electromagnetic proportional flow control valve for adjusting the driving speed.

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, a pump for supplying fluid to said actuator, a pilot operated meter-in valve to which the fluid form the pump is supplied for controlling the direction of movement of the actuator, and pilot operated meter-out valves associated with each opening of the actuator for controlling the flow out of said actuator. The pressure of fluid being supplied to the actuator by the meter-in valve is sensed and caused to produce a force opposing the movement of the meter-out valve controlling flow from the actuator.

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 hydraulic system for operating a pressurizable load off a pressure source having a high-pressure side and a low-pressure side has a main valve having a load side connected to the load and a source side connected to both sides of the source and displaceable between one position permitting flow from the source to the load and another position for opposite flow. Respective fluid-operated actuators displace the valve into its positions. A controller has an input side connected to the high-pressure sides of the source at the source side of the valve and an output side connected to the load at the load-side of the valve and with the sump at the source side of the valve. This controller also is connected to the actuators for pressurizing same alternately and thereby moving the valve between its positions.

Abstract: A hydraulic system in which a pilot operated hydraulic four-way main valve (11) controls the direction and rate of fluid flow to a hydraulic load (13), includes a flow sensor (15) which is capable of operating bidirectionally and may therefore be located in one of the service lines (25, 26) from the main valve (11) to the load (13). The main components of the flow sensor are a variable or fixed aperture flow sensing orifice (52, 53), and a pressure transducer (18) to which the pressure differential developed across the orifice is applied and which converts the pressure differential into an electric negative feedback signal. This electric feedback signal is compared in an electronic circuit (17) with a demand signal, and a corresponding command signal sets the pilot valve (12) which controls the main valve (11).

Abstract: A control system for a fluid pressure operated actuator includes an arming valve having open and closed positions and a pilot operated selector valve having a neutral position and an extend position. The arming valve is connected to a source of fluid and the selector valve is connected to the arming valve so that two control inputs are necessary to connect the source to an operating chamber of the actuator. A solenoid actuated pilot valve is connected to the source and to a sump and has an on position in which the flow of fluid is unblocked and in an off position in which the flow of fluid is blocked. A pilot passage connects the pilot valve to a pilot chamber of the selector valve and a branch passage connects the pilot passage and the operating chamber of the actuator so that the operating chamber communicates with the sump whenever the pilot valve is off regardless of the position of the selector valve.

Abstract: An air pressure control system for use where a plurality of various sequential and repetitive air pressures are selectively required. A pilot air operated pressure regulator valve having a pilot air operator and a working air flow control valve are connected in series in a pressurized working air conduit between a source of pressurized air and an air cylinder. A pilot air pressure selector circuit means, for selectively and sequentially providing a plurality of pre-set pilot air pressures to the pilot air operator of the pilot air operated pressure regulator valve, includes a plurality of pressurized pilot air conduit means which are connected in parallel with each other, and with one end of each pressurized pilot air conduit means being operatively connected to the source of pressurized air and the other end thereof being operatively connected to the pilot air operator of the pilot air operated pressure regulator valve.

Abstract: An apparatus for positioning an adjustable member as a function of a command signal and a control condition, especially for the positioning of a hoisting mechanism on a tractor or the like, comprises an operating circuit and a control circuit. The operating circuit has a bidirectional positionable valve with a valve side and first and second control devices for regulating flow of pressure medium from a supply tank to the adjustable member. The control circuit connects a control pressure medium source to the control devices at first and second junctions and includes adjustable throttles and a flow-regulating valve. A first adjustable throttle is connected between the supply tank and the first junction. The second adjustable throttle is connected between the control pressure medium source and the first junction and in series with the first adjustable throttle.

Abstract: A hydraulic power system having a variable displacement hydraulic pump, a hydraulic motor driven by the hydraulic pump for actuating a load, with the pump and motor being connected to constitute a closed hydraulic circuit. A hydraulic servo controls the displacement volume of the pump, and a motor stop arrangement prevents, in its operative position, the motor from rotating. The system includes a control valve responsive to a main line pressure in the closed hydraulic circuit for controlling a hydraulic fluid supply to the hydraulic servo to prevent the main line pressure from substantially exceeding a predetermined level, and a control is responsive to the operation of the hydraulic servo for releasing the motor stop arrangement from the operative position when the hydraulic servo is operating.

Abstract: A control valve arrangement includes at least one first supply and exhaust valve, and a second supply and exhaust valve. The first and second valves are arranged in series and are manually operated with a single hand. The first valve is manually displaced in one direction, and the second valve is displaced in the opposite direction.

Abstract: In a pneumatic nailer using compressed air for driving nails, a work chamber contains a drive piston and is in communication with a storage chamber for effecting the return of the drive piston after it has driven a nail. A valve unit controls the supply of additional compressed air into the storage chamber. A switching element is arranged to react when a predetermined compressed air pressure is exceeded for controlling the flow of compressed air through the valve unit to the storage chamber. The switching element can be a pressure limiting valve. The combination of the switching element and valve unit avoids unnecessary compressed air losses in the higher pressure operating ranges.

Abstract: A fastener driving tool includes a control assembly that allows the tool to be fired sequentially by first placing the tool against a workpiece followed by actuation of a trigger to fire the tool. The control assembly includes a valve assembly that allows the tool to be selectively adjusted to operate in a multi-shot sequence or a single shot sequence. In the single shot sequence the tool may only be actuated once upon placement of the tool against a workpiece and subsequent actuation of the trigger. The tool must be removed and repositioned on the workpiece before the tool can again be fired. In the multi-shot sequence, the tool may be repeatedly fired by repeated actuation of the trigger once the tool has been placed on the workpiece.

Abstract: A first front face of a main control spool of a main control valve is loaded with a constant pressure, whereas the opposite face is loaded with a controlled pressure to control the fluid passages to and from a hydraulic actuator. The control pressure is adjusted by means of a two-edge control of the pilot control spool of a pilot control valve which is actuated by a single proportional solenoid against the force of a spring. The advantages obtained thereby result in a substantial savings in manufacturing expenditure and a substantially improved control operation.

Abstract: A tamper-proof railroad hopper car door operating system for preventing operation of the doors when the auxiliary train line air pressure, and thus the locomotive engine, is removed. A directional control valve is provided through which air pressure is switched from the car reservoir pressure tank to control a door operating air cylinder. The control valve includes a pilot inlet connected to the auxiliary train line for supplying air pressure to switch the control valve, while the reservoir air pressure flows through the valve to supply the power medium for the air cylinder. In this manner when the auxiliary train line air pressure is removed, reservoir air pressure cannot be switched to move the hopper car door.

Abstract: In one form of the present invention, a plurality of serovalves are connected to a common manifold. The manifold transmits fluid pressure from the servovalves to a modulator piston which controls the fluid pressure applied to a hydraulic actuator piston. The servovalves are designed such that, if the fluid pressure provided by any one of them to the manifold falls below a threshold, then the servovalve disconnects itself from the manifold, allowing control of the modulator piston to be assumed by the remaining, functioning servovalves. The present invention can be used in control surface actuators of short takeoff and landing (STOL) aircraft.

Abstract: A hydraulic fluid circuit of a hydraulic shovel including a first directional control valve group connected to a first hydraulic pump and including a first directional control valve and a second directional control valve respectively connected to a first hydraulic cylinder and a second hydraulic cylinder. A second directional control valve group, connected to a second hydraulic pump, includes a third directional control valve having a first working port connected to one cylinder chamber of the first hydraulic cylinder and a second working port connected to one cylinder chamber of the second hydraulic cylinder.

Abstract: An arrangement for controlling a hydraulic motor having supply and discharge sides, has a throttling directional valve having supply and discharge sides and a port, a speed lowering brake valve controlling the discharge side of the hydraulic motor and having a control piston with a control side and a port connected with said port of said directional valve, a control valve arrangement between the control side of the control piston and the supply side of the hydraulic motor and having end sides with end side ports, the control valve having a control slider which selectively connects the control side of the control piston with the supply side of the hydraulic motor and disconnects the control side of the control piston from the latter, is constantly connected at the end side ports with the discharge side of the hydraulic motor prior or after the directional valve and connects the discharge side of the hydraulic motor after the directional valve with the control side of the control piston or disconnect the discha

Abstract: The present invention relates to a device for controlling two fluid-controlled drive members, one of which is double-acting, wherein a communication conduit connects the supply conduits of said double-acting drive member, a non-return valve being disposed in said communication conduit and allowing the passage of the fluid solely from the small chamber towards the large chamber of said double-acting drive member, while another conduit is adapted to connect the large chamber of the double-acting drive member to the chamber of the second drive member. The result of the invention is the elimination of lift of a hydraulic loading shovel when digging.

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 device for the positioning of an adjustment element dependent upon a desired level and the actual level, particularly for the adjustment of a hoist gear train of a tractor, a combine or the like, has an operating circuit 10, which has a multi-way valve 3 pressure-operated in two directions, and a control circuit 29 for the operation of the multi-way valve, connected to a pressure source 19, which is connected to two control devices 11, 12 of the multi-way valve. Circuit 29 has two adjustable series-connected throttles 22, 24, connected to one of the two control devices. The first throttle 24 is also connected to a tank 7 and the second throttle 22 is also connected to pressure source 19. Both throttles have the same maximum flow-through cross section, and are adjustable in the same manner. Third and fourth throttles 27, 28 are provided, one being between the pressure source and control device 11, and the other between the control device and tank 7.

Abstract: A shear-type, fail-fixed servovalve is disclosed which includes a piston whose piston head is movably disposed in one chamber of a multi-chamber housing. A piston rod is attached to the piston head and extends into the other chambers. Two passages extend through the piston rod and communicate with the chamber on opposite sides of the piston head. A pair of input orifices are located proximate each other at one end of the piston rod, each corresponding to one passage. An angularly movable jet pipe emits fluid directed at the input orifices. The jet pipe has a null angular position disposed at a predetermined offset angle with respect to the axis of the piston rod, and directs fluid towards the pair of orifices. Means responsive to a selectively variable control signal for changing the angular position of the jet pipe is provided which is effective to produce a magnified linear piston displacement by varying the relative amounts of fluid supplied to the input orifices.

Abstract: A master/slave fluid-pressure apparatus having a first valve respective to angular movement of a master arm for producing fluid pressure which is applied as a pilot pressure to shift a closed-center three-position directional valve in one direction, which then allows a fluid-pressure actuator to be operated to cause a slave arm to follow the master arm in angular motion. The angular movement of the slave arm actuates a second valve coacting therewith to develop a fluid pressure which is applied as another pilot pressure to the directional valve. When the fluid pressure from the second valve reaches a predetermined point, the directional valve is shifted in the opposite direction to stop operation of the fluid-pressure actuator. The first and second valves may either be pressure reducing valves or relief valves.

Abstract: A fluid system (10) having a directional control valve (12) operated by a pilot valve (11) having a manually operable control handle (22) for selectively controlling a fluid motor (14) in positioning a load (17). The pilot valve (11) includes a spool (31) cooperating with associated portions of the pilot valve to provide a pressure regulated pilot signal to the directional control valve during normal operation of the system. Spool (31) includes a recess (98) which is placed in communication with the high pressure portion of the motor cylinder (16) during a dead engine condition by manipulation of handle (22) to provide pressure regulated delivery of the fluid from the motor (14) through recess (98) and to the conduit normally controlling the directional control valve for effecting a controlled lowering or retraction of the load. A single pilot valve is utilized for effecting the pressure regulated control in both normal and dead engine conditions.

Abstract: A four-function valve for operating a 2-way hydraulic cylinder has a pair of solenoid-operated pilots. The valve also includes a pair of valve members and a pair of poppet members, all slidable within bores in a pair of hollow sleeves. The solenoid-operated pilot valves control pilot pressure communication to the valve members to control movement of the valve and poppet members. Each poppet member has a pair of seats, one engageable with a shoulder on the sleeve to control fluid flow between a pump and the cylinder, the other engageable with an end of the corresponding valve member to control fluid flow between a sump and the cylinder.

Abstract: A control system for a plurality of hydraulic actuators which requires smaller number of control valves than that of actuators. In one embodiment, three control valves are arranged in parallel for controlling four hydraulic cylinders. The control valves are preferably solenoid-operated and one of control valves are used for supplying a pilot fluid pressure into a plurality of pilot-operated check valves disposed between the control valves and the hydraulic cylinders.

Abstract: A valve body is disclosed located in the hydraulic system of a machine which valve serves to direct hydraulic fluid under pressure to hydraulic components or divert the fluid to a system reservoir to prevent component operation. A check valve in the valve body is opened or closed by control means with the check valve indirectly determining the position of a pressure responsive spool for either normal fluid passage to hydraulic components or fluid diversion back to a reservoir. Remote actuation of the control means is by a hand operated air, lockable pump to enable an authorized equipment operator to remotely actuate said control means to effect locking or unlocking of the hydraulic system by positioning the check valve. A modified check valve control dispenses with the air pump and utilizes a lock plunger to bias the check valve to a closed position for normal hydraulic system operation or, conversely, to open the check valve to divert pressurized fluid back to a system reservoir.

Abstract: For operating the rollers and the steam chest in a laundry flatwork ironer a hydraulic system is provided which includes a hydraulic motor for driving the rollers, hydraulic cylinder-and-piston units for raising the steam chest, and a pump for operating the motor and the cylinder-and-piston units. Valves between the pump and the motor are selectively operable to establish low pressure standby operation of the pump with the hydraulic motor off, or low speed operation of the motor to jog the rollers or higher speed operation of the motor to drive the rollers at a speed appropriate for laundry flatwork. Other valves between the pump and the cylinder-and-piston units are selectively operable to raise the steam chest, reduce the cylinder pressure after the steam chest has been raised, and to increase the cylinder pressure whenever laundry flatwork is in the ironer.

Abstract: Fluid control systems frequently eliminate use of fluid operated jack protecting relief valves because additional visibility blocking and damage prone conduits are required to connect the relief valves to the reservoir. A fluid operated system having a controlling valve, a selecting valve, a fluid operated jack, a relief valve, a reservoir and a bypass valve is provided to controllably connect the relief valve to other portions of the system in response to the position of controlling valve and selecting valve. Therefore, no additional conduits are required to connect the relief valve to the reservoir and thus the problems of reduced visibility, premature conduit leakage and conduit damage are eliminated. The fluid control system is particularly suited for use in a work vehicle such as a lift truck having a lift mast.

Abstract: An improved trigger valve for a pneumatic nailing machine is disclosed. A communication hole between the main air chamber and the pilot air chamber is made as small as possible. This allows the trigger valve to return in a delayed manner so that the head valve and driver piston operate properly.

Abstract: A pneumatic valve is disclosed, for controlling the position of a ram in a partly-extended condition. The valve has a combination of rubbing seals and diaphragms, for smooth operation and reliability. A spring-loaded plunger presses the diaphragm against the mouth of a port, to seal off the port. A piston with rubbing seals lifts the plunger from the diaphragm, to open the port. The piston seals rub against plastic, for freedom from water contamination problems, while the diaphragm provides the high integrity seal needed to control the ram position. A particular application of the valve is to the air control of dentist's chair, medical table or medical chair.

Abstract: A control device for the sequential control of an advancing mine-roof support comprising pressure-controlled directional control valves alternately connectable to a high pressure line and to a return line in order to convert a pressure pulse into a switching step at the main control unit of the advancing mine-roof support and for transmitting an answering pressure pulse signalling the completion of the workstage for continuing the sequence.

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, a pump for supplying fluid to said actuator, a pilot operated meter-in valve to which the fluid from the pump is supplied for controlling the direction of movement of the actuator, and pilot operated meter-out valves associated with each opening of the actuator for controlling the flow out of said actuator. The pressure of fluid being supplied to the actuator by the meter-in valve is sensed and caused to produce a force opposing the movement of the meter-out valve controlling flow from the actuator.

Abstract: In an electro-hydraulic control assembly for turbine valves, including a shaft for the turbine valve, a valve housing, electrical control means, an electro-hydraulic converter connected to the electrical control means, a hydraulic control cylinder being connected to the electro-hydraulic converter, a control piston being movable in the cylinder in a valve opening and a valve closing direction and being connected to the valve shaft, a force storing spring loading the piston in the valve closing direction, and a hydraulic system including a hydraulic fluid reservoir, a fluid pump being fed from the reservoir and having a pressure side, an electric motor for driving the pump and a hydraulic pressure accumulator connected to the pressure side of the pump, the improvement including a support structure disposed in the housing including two mutually parallel support plates, the spring being disposed between the support plates, the electro-hydraulic converter, the cylinder and the supply system being fastened to the

Abstract: The servovalve includes a primary jet of fluid. A variable control signal is adapted to vary the angular position of the primary jet from its maximum recovery position. A first fluid path is adapted to supply fluid to a servopiston at a variable pressure determined at least in part by the control signal. A second fluid path is adapted to receive a predetermined portion of the primary jet fluid when the control signal reaches a predetermined value. The second fluid path terminates in the vicinity of the primary jet and is adapted to direct a secondary jet of fluid at the primary jet to deflect the primary jet toward the input orifice of the second fluid path. The resultant positive fluid feedback in the second fluid path causes the primary jet to latch in a first angular position relative to the maximum recovery position when the control signal reaches a predetermined value.

Abstract: A hydraulic control device for the pressurization of a clutch or the like for a transmission operable under load comprises a spool-type valve displaceable in one direction to pressurize the clutch and in the opposite direction to vent the same. The valve spool operates with a damping piston which receives the clutch pressure buildup and acts against a control piston which, in turn, is displaced by an operative valve. According to the invention, the pressure head is maintained substantially constant by providing a sleeve or bushing within the damping piston chamber which bears against the spool by a spring and which can be biased by a spring between the damping piston and the sleeve.

Abstract: A static leak seal assembly for use in a conventional compressor for preventing high pressure gas leakage from occurring through the spaces between a movable piston rod and a frame of the machine when the rod is motionless is disclosed. A piston is mounted on the rod for axial movement between retracted and extended positions. A follower ring is disposed around the rod and is likewise movable in an axial direction along the rod between retracted and extended positions in response to corresponding movement of the piston. When moved to its extended position by the piston, the follower ring engages a compressible, resilient collar to compress a neck of the collar inwardly against the rod to effect a substantially fluid tight seal therearound. The ring is separate and distinct from the piston to permit the former to adjust in radial disposition about the rod to uniformly compress the collar neck against the rod around the entire periphery of the latter.

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 arrangement for controlling the lifting mechanism of a tractor or a harvester or a harvester combine comprising a hydraulic actuator (17) connected to the lifting mechanism and controlled by a control valve (19) leaving a hydraulically controlled spool arranged in the bridge diagonal (27-19-27') of a hydraulic bridge circuit (23, 24, 25, 26), in the bridge branches of which two actual force value transducers (41, 42) for generating hydraulic signals proportional to the position of the lifting mechanism and desired force value setting means (32, 52) are respectively located for controlling the hydraulically controlled valve (19). An additional control valve (33) or throttle unit (53a) is provided for selecting one or both of the actual force transducers and if desired for controllably mixing the actual force signals.

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: There is disclosed an automatic firing system for pneumatic tools wherein there is a remote valve to produce actuation of the main valve of the device which remote valve has only one moving part, combined with a selector valve, by means of which the tool may be converted from single fire to auto-fire modes, and in the auto-fire mode the rate of fire may be controlled. The pneumatic circuitry is such that less compressed air is used than in conventional auto-fire tools and thus the tool is more economical than prior art tools.