Pilot valve (304)

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This subclass is indented under subclass 418.  Apparatus in which the valve means comprises a main or primary valve which is movable by fluid under pressure to control the flow of motive fluid to or from the motor and a secondary or pilot valve operable to control the application of pressure fluid to the main valve, or a fluid actuator therefor, so as to control movement of said main valve, said fluid under pressure being separate or separated from the motive fluid controlled by the main or primary valve and not entering the working chamber.

SEE OR SEARCH THIS CLASS, SUBCLASS:

304through 314, for cyclically operable expansible chamber motors having a pilot valve controlled distributor. NOTE "PLACEMENT OF PATENTS" IN THE CLASS DEFINITION AND THE PARAGRAPH FOLLOWING THE TITLE IN THE SCHEDULE OF THIS CLASS.


 
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Patent Number
Title
  Date
3941534 Injection molding control system Mar-2-1976
An injection molding control provides for the programmable control of ram velocity as a function of the position of the ram through closed-loop feed-back of the measured actual velocity. Closed-loop feed-back of the actual mold cavity pressure overrides the velocity program in an analog fashion to stop...     
3943715 Servo mechanism Mar-16-1976
A servo mechanism for a prime mover interconnected to a hydrostatic transmission includes a source of pressurized fluid, a fluid reservoir, an actuator having a piston operatively connected to the hydrostatic transmission and being provided with large and small hydraulic receiving areas which are exposed...     
3948148 Devices for controlling pneumatic actuators Apr-6-1976
1. A device for controlling a pneumatic actuator comprising a working piston, a working chamber in which a pressure varying as a function of the effort to be exerted by said working piston is to be produced, a body, a cylindrical bore formed in said body, a regulating piston slidably fitted in said cylindrical...     
3964504 Leveling valve Jun-22-1976
A hydraulic valving mechanism for controlling an object in a normally level position such that upon a shifting of the same from level an actuating mechanism is driven to return the object to the desired level, such valving mechanism including a valve housing with control ports therein with a gravity...     
3968729 Fluid-operated apparatus exhibiting hysteresis effect Jul-13-1976
A fluid-operated apparatus receiving an input pressure signal exhibits a hysteresis or deadband effect by responding to an increasing pressure signal at a first level and a decreasing signal at a second and lower level. The apparatus includes a spool valve to which the input pressure signal is applied...     
3968732 Hydraulic power transmission system Jul-13-1976
In a system comprising first and second drive units each including one or more hydraulic motors, a two-position valve is provided in circuit with the motors of one drive unit, the motors of the other drive unit being supplied independently of the valve; the valve has a first operative position for blocking...     
3972503 Servo pressure operated piston arrangements Aug-3-1976
A servo-pressure operated piston arrangement includes a pilot valve which is movable by a torque motor against a biasing spring. A closed chamber is defined between one end of the piston and its surrounding cylinder, and this chamber communicates with an orifice which is shut by the pilot valve, under...     
3976098 Hydraulic motor control apparatus Aug-24-1976
A hydraulic motor control apparatus comprising a plurality of standard multiple function modules adapted to be selectively programmed in various arrays to effect substantially any required hydraulic control function.
3980348 Fluid flow control valves Sep-14-1976
A diaphragm valve has a relatively long seating formed by a plurality of ribs which engage with one air operated diaphragm. An annular valve is provided by slotting the outer surface of an annular seating member which engages an endless diaphragm, alternate slots communicating with the inlet or outlet...     
3988966 Fluidic repeater Nov-2-1976
Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressureload characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor means...     
3995533 Hydraulic steering unit Dec-7-1976
The invention relates to a hydraulic steering unit for automotive vehicles. A main feature of the unit is that pressure relief means are provided for relieving excessively high pressures developed in the unit which are caused by the steered wheels encountering road obstacles. The unit includes a pump,...     
3996840 Control circuit of actuator Dec-14-1976
A control circuit for an actuator having an operation valve for selectively distributing hydraulic oil from a pump to plural actuators which has a plurality of conduits, a plurality of pilot-operated valves for controlling the flow direction of oil to the actuator side or the tank side, and a pilot spool...     
4007666 Servoactuator Feb-15-1977
A servoactuator for stopping a ram in its existing position or retracting the ram at a fixed rate to a locked position.
4030655 Improved fastener applying device Jun-21-1977
A pneumatic fastener driving tool in which a piston-driver assembly is moved in opposed working and return strokes within a cylinder. Vent passage means of a predetermined area are provided adjacent the lower end of the cylinder to permit greatly increased velocity on the working stroke. Valve means...     
4033233 Fluid pressure operable servo positioner Jul-5-1977
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...     
4045994 Compressed air rivet setting tool Sep-6-1977
An air-powered blind rivet setting tool including a pivotable transmission linkage between the compressed air powered piston rod unit and the rivet pulling mechanism including a valving arrangement for accomplishing cyclical operation of the tool.
4046059 Fluidic repeater Sep-6-1977
Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor...     
4072169 Hydraulic control system Feb-7-1978
A hydraulic control system has a three-position valve which in its central position disconnects the high-pressure and low-pressure sides of a pressure source from outlet lines but connects these sides of the source together through a low-pressure valve. Moved to either of its end positions the valve...     
4083381 Control valve Apr-11-1978
A control valve for controlling flow relative to a pair of control ports which includes a pair of 3-way valve components each having one of the control ports and a poppet valve member which, when closed in one position under pilot control, blocks pressure flow to a control port and connects the control...     
4085658 Operating means Apr-25-1978
Operating means comprise an air cylinder and a hydraulic cylinder mounted in axial alignment. A rod passes through both cylinders, and a piston in the air cylinder is mounted on the rod. A hollow member which is positioned about the rod passes through the hydraulic cylinder and extends from the ends...     
4089171 Four position valve assembly May-16-1978
A hydraulic power circuit for operating hydraulic motors at several speeds includes first and second fluid sources and a valve assembly for combining flow from the second source with flow from the first source as a faster motor speed is required. The valve assembly includes a first valve controlling...     
4089172 Position controller May-16-1978
A device for infinitely controlling the position of a controlled member along its axis of movement. The device includes hydraulic actuators coaxially secured to the controlled member and a mechanically and/or manually actuated cylinder is fluidly connected to the hydraulic actuator so that by actuation...     
4094229 Fluidic repeater Jun-13-1978
Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor...     
4096784 Hydraulic power system Jun-27-1978
An hydraulic power system comprising a dual acting work piston adapted to be operatively connected to an external mass to be moved, the piston being instantly directionally responsive to a pair of control valves adapted to be sequentially opened and closed to actuate the work piston for movement in opposite...     
4098171 Pneumatic piston apparatus Jul-4-1978
An improved pneumatic piston apparatus is provided wherein a movable poppet valve member employs at least one composite member exposed to air pressure which varies dynamically during the operation of the apparatus. Delamination of the composite member and resultant malfunction of the poppet valve are...     
4104954 Hydraulic control system Aug-8-1978
The invention is a hydraulic control system for use in positioning and clamping a movable object on a support, which system is adapted to be connected to a source of pressurized hydraulic fluid, to a hydraulically operated piston-cylinder assembly connected to the movable object for moving the movable...     
4117767 Compressed air-operated fastener driver Oct-3-1978
The invention pertains to a compressed air-operated fastener driver utilizing a piston reciprocally mounted within a cylinder wherein a control valve at one end of the cylinder selectively opens and closes cylinder ports communicating with a compressed air source, and the control valve utilizes an exhaust...     
4119016 Hydraulic control device Oct-10-1978
A hydraulic control device for use in a hydraulic system having a pump supplying fluid from a reservoir to a working circuit. The control device detects leaks in the working circuit by monitoring the level of hydraulic fluid in the reservoir. In the event of a drop in the level of hydraulic fluid beyond...     
4126082 Travel-brake control system Nov-21-1978
A hydraulic control system for use with a vehicle having an earthworking implement and having a plurality of components operated by hydraulic motor means having hydraulic release type brakes associated therewith and including means responsive to actuation of the brake for precluding operation of the...     
4132152 Closed loop electro-fluidic control system Jan-2-1979
Two embodiments of closed loop electro-fluidic controlled systems are disclosed for controlling the velocity, acceleration, torque, force or pressure applied to the member. The system includes a source of electrical command signals correlated to the desired magnitude of the parameter being controlled,...     
4137825 Fluidic repeater Feb-6-1979
Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor...     
4145956 Pilot operated stepping valve Mar-27-1979
A pilot operated stepping valve where an electrical pulse motor drives a pilot valve spool which controls the flow of hydraulic fluid driving a main valve spool which actuates a hydraulic motor or actuator. The main valve spool follows the pilot spool and is hence sensitive to the pulses received by...     
4145957 Pilot-operated valve structure Mar-27-1979
A pilot-operated valve structure for controlling high pressure fluid flow relative to a pair of cylinders, each having an extend port and a retract port. The valve structure has a pair of pilot-operated 3-way valves, each with a poppet valve member and with pilot valve structure including pilot lines...     
4148248 Hydraulic valve control system Apr-10-1979
A hydraulic valve system particularly adapted for controlling a hydraulically powered elevator. The system involves essentially a bypass valve which selectively bypasses hydraulic fluid from the pump directly back to the tank during the up mode operation, thereby controlling the up speed of the elevator;...     
4152971 Fluidic repeater May-8-1979
Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor...     
4159671 Self-advancing mine roof supports Jul-3-1979
A self-advancing mine roof support is provided, in addition to the normal manually operable control valve means for controlling raising and lowering of the roof-engaging structure of the support and operation of the advancing means, with an automatic sequence control valve means operable in response...     
4159778 Straddle carriers for containers Jul-3-1979
A straddle carrier consisting of an inverted U-shaped frame, having a pair of vertically extending legs that define an elongated container carrying bay with each leg supported by a plurality of wheels is disclosed herein. First and second engines are respectively supported on the legs and each engine...     
4161135 Fail safe fluid power device Jul-17-1979
A fluid power device such, for example, as one for opening and closing clam shell gates is operated by a ram under fluid pressure. A tank is provided for storing fluid under pressure and by a system of valving extension of the ram, as for a gate opening operation, is inhibited until enough fluid under...     
4161136 Hydraulic jack control device Jul-17-1979
A control unit for controlling the supply of fluid to a hydraulic jack, the control device including a main valve having a valve member normally held closed by pressure in a pressure chamber, the pressure chamber being fed with fluid through a bore in a valve member of the main valve. In one embodiment,...     
4161905 Hydraulic servomechanism Jul-24-1979
Disclosed is a hydraulic servomechanism wherein the motion of a driven element is synchronized with the motion of a command element by detecting any phase difference between the movement of the driven element and that of the command element, controlling the flow rate of a hydraulic fluid being fed to...     
4166506 Controlling apparatus for bulldozer blade Sep-4-1979
A controlling apparatus for bulldozer blade in which the control is carried out automatically or manually. The apparatus comprises an electromagnetic valve for controlling a cylinder of the bulldozer blade, a switch for changing the control of the bulldozer blade automatically or manually, a safety relay...     
4174017 Vehicle power assisted steering apparatus Nov-13-1979
A steering system includes a sensor device which is responsive to excessive steering effort to actuate a power assist for steering. A housing rotatably receives an input member and an output member which are rotatable relative to each other when the steering effort is excessive. The housing includes...     
4184334 Closed center draft control valve Jan-22-1980
A variable displacement pump supplies fluid to the single acting draft control cylinder of an agricultural tractor through a valve for controlling flow to and from the draft control cylinder. The valve houses a control rod activated valve spool that when displaced allows fluid to unseat a check valve...     
4201052 Power transmission May-6-1980
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...     
4202247 Closed loop electro-fluidic control system May-13-1980
Two embodiments of closed loop electro-fluidic controlled systems are disclosed for controlling the velocity, acceleration, torque, force of pressure applied to a member. The system includes a source of electrical command signals correlated to the desired magnitude of the parameter being controlled,...     
4217810 Regulation system for steam turbines Aug-19-1980
A regulation system for steam turbines which includes a servomotor controlled by a servovalve (1) and two safety valves (31, 31') controlled by two electrically-operated valves (19, 19'). When the control inlet (7) of the servomotor is connected to the drain pipe (6) by at least one of the safety valves,...     
4221155 Vibration-free hydraulic power system Sep-9-1980
A vibration-free hydraulic power system having an opposing pair of pistons adapted to be moved in unison with the same stroke and equal force, but in opposite directions, one of the pistons being operatively connected to an external mass to be moved, the other of the pistons being operatively connected...     
4223592 Pneumatic operating-mechanism construction Sep-23-1980
An improved pneumatic operating mechanism construction is provided including the usual stationary operating cylinder with a movable reciprocally-operable driving piston member movable therewithin, and having an extremely-fast pneumatic valve-device cooperable with a movable valve-sealing member attached...     
4227440 Fluidic repeater Oct-14-1980
A fluid repeater system may be balanced so that displacement of the load has a desired correspondence to displacement of the transmitter. This may be done by making the fluid resistance offerd to fluid flowing along a path from the source to the reservoir and through the feedback controlled directly...     
4235155 Delaying control for hydraulic motors Nov-25-1980
A delaying device for a fluid system for operating a hydraulic motor (10) wherein electrically operated pilot valves (39,40) are actuated by limit switches (13,13') in the motor to control flow through pilot lines (37,38) into a control block (20) and then to and from the motor, said delaying device...     
4254689 Fluidic repeater Mar-10-1981
A fluidic repeater comprising: transmitter means, a responder, a single line for transmitting pressure signals between said transmitter means and responder, and means including a source of pressure fluid for causing a pressure fluid to flow through said line.
4261249 Hammer Apr-14-1981
A fluid operable hammer including variable volume exhaust chamber means for receiving motive fluid and improved motive fluid inlet and exhaust valve means cooperable with the exhaust chamber means.
4276809 Simplified fail-fixed servovalve Jul-7-1981
A simplified fail-fixed electrohydraulic servovalve for operating with a source of fluid under pressure, and a piston translatably disposed within a bore. The piston has a rod side face area which is less than its head side face area and translates in a first direction for electrical input signals above...     
4287813 Two-stage concentric hydraulic brake booster Sep-8-1981
Booster providing both hydraulic feed-back and hydraulic feel-back in a two-stage operation in which we boost-brake a vehicle. Concentric, nesting, inner and outer control parts include, as the sliding outer part, a brake-pedal-connected input signal spool or sleeve for developing a desired signal pressure...     
4289063 Hydraulic driving device Sep-15-1981
A hydraulic driving device of a circuit breaker which opens and closes a system in response to two signals is principally constructed of a cylinder, a piston, and a main control valve for controlling the motion of the piston. A spool adapted to slide within the main control valve has its motion controlled...     
4296910 Hydraulically controlled safety valve Oct-27-1981
A safety valve is mounted on an underwater oil well and is remote-controlled from a central control station. The control station is connected to a receiving station, where the valve is disposed, via a single small-section hydraulic line which feeds, at a low rate of flow, a hydropneumatic accumulator...     
4311296 Cartridge element control Jan-19-1982
A system for regulating the flow of a fluid in dependence of an input signal includes a valve housing, a valve between an inlet and an outlet of the valve housing, a cylinder substantially closed off from the cartridge valve housing, and a piston in driving connection with the valve, and movable within...     
4316486 Electrohydraulic control apparatus Feb-23-1982
The invention relates to an electrohydraulic control assembly of the type having a slide valve unit for controlling the operating direction of a hydraulic servomotor. The assembly includes a bridge circuit between the pressure source and the drain tank which has a pressure operated valve in each of its...     
4319705 Fastener driving tool Mar-16-1982
A tool for driving fasteners includes a casing defining a nose portion and a handle portion within which is a reservoir for pressurized fluid. A driver is mounted in the nose portion that is reciprocated by a piston attached thereto and an assembly for returning the piston to a static position after...     
4335645 Fluidic repeater Jun-22-1982
A fluidic Repeater, includes a rotary transmitter, a responder, and a rotary feedback. Various constructional features useful in conjunction with the system are disclosed.
4343972 Hydraulic drive for electrical switches Aug-10-1982
A hydraulic drive for an electrical switch is disclosed including magnetically operated control signal organs for initiating closing and opening of the electrical switch which is hydraulically driven by a drive with a differential piston moving in a drive cylinder. A switch-over control valve is employed...     
4350209 Hydraulic draft control valve Sep-21-1982
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...     
4353289 Power transmission Oct-12-1982
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, pilot operated meter-in valve means to which the fluid from...     
4353290 Pneumatic control valve and circuit Oct-12-1982
A pneumatic circuit includes a source of fluid pressure 11, a selector valve 12, a control valve 14, and a power cylinder 15. The control valve 14 includes main valves 35 and 45 and a pilot interlock valve 27. The main valves 35 and 45 include a main inlet port 36, a main exhaust port 38, and cylinder...     
4362089 Valve system Dec-7-1982
A fluid power control system (17) having an improved control valve (20) providing reduced regulated pressure fluid selectively from a high pressure pump supply (P) or the fluid motor (10) under conditions wherein the pump supply has failed to supply the desired pressurized fluid. The system utilizes...     
4367765 Flow regulator for hydraulic circuits Jan-11-1983
The regulator is designed to control the flow of a pressurized fluid between a source of said fluid which feeds it at a feed pressure, and a user device in which the fluid is at a utilization pressure which depends on the operating conditions of the device; the regulator also comprises a valve element...     
4372193 System with constant force actuator Feb-8-1983
A control mechanism (48) is provided to controllably maintain a constant force on an actuator (18) and provide fluid flow to a downstream control valve (24) by controlling a pilot differential pressure between first and second ends (38,40) of a pilot operated control valve (14). A two position valve...     
4375223 Dial operated pressure regulator Mar-1-1983
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...     
4385493 Hydraulically assisted steering device May-31-1983
Pump pressure in a fluid power assisted steering device is regulated through the suction side of the pump to supply pressurized fluid to a servomotor through a fluid pressure actuated steering control valve. A pre-control valve controls pressure in an actuating chamber of the steering control valve in...     
4391183 Hydraulic blocking valve Jul-5-1983
The invention relates to a hydraulic blocking valve, a so-called holding valve (10), the shutting-off member of which consists of a movable ball (16) coacting with a seat (17) in an inlet chamber (24). The space (15) on the side of the ball opposite its seat forms an operating chamber (15), and both...     
4392415 Control for dead engine lower Jul-12-1983
A mechanism (80) is provided to controllably lower an actuator (28) upon the loss of a source (62) of pilot fluid in a fluid system requiring a float condition of operation. A resolver (80) is located in a vent line of a make-up valve and is connected to a second load supporting end (32) of the actuator...     
4404892 Hydraulic operating apparatus Sep-20-1983
A hydraulic operating apparatus including an actuating cylinder having a piston arranged therein and moved by a fluid under high pressure further includes a control valve having only one metallic seal whether the piston is at its upper or lower positions. The control valve is operative to apply the fluid...     
4404897 Fluidic repeater Sep-20-1983
Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor...     
4407122 Power transmission Oct-4-1983
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, pilot operated meter-in valve means to which the fluid from...     
4437385 Electrohydraulic valve system Mar-20-1984
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...     
4464976 Two-stage pneumatic servomotor Aug-14-1984
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...     
4475442 Power transmission Oct-9-1984
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...     
4476898 Mine-roof support control means Oct-16-1984
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...     
4479678 Pneumatic valve Oct-30-1984
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...     
4487106 Fluid operated system Dec-11-1984
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...     
4506700 Poppet valve with float function Mar-26-1985
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...     
4509404 Master/slave fluid pressure apparatus Apr-9-1985
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...     
4510848 Shear-type fail-fixed servovalve Apr-16-1985
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...     
4516472 Hydraulically-operated breaking device May-14-1985
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...     
4526085 Hydraulic loading shovels Jul-2-1985
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...     
4538504 Fail-safe servovalve system Sep-3-1985
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...     
4543875 Electro-hydraulic directional control valve Oct-1-1985
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...     
4550643 Fastener driving tool Nov-5-1985
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...     
4554861 Pneumatic nailer Nov-26-1985
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....     
4564047 Control valve Jan-14-1986
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...     
4571941 Hydraulic power system Feb-25-1986
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...     
4598626 Feedback controlled hydraulic valve system Jul-8-1986
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...     
4606258 Self-pressurizing hydraulic control system Aug-19-1986
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...     
4611527 Power transmission Sep-16-1986
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...     
4611528 Power transmission Sep-16-1986
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...     
4616476 Cylinder driving apparatus Oct-14-1986
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...     
4627239 Hydraulic circuit arrangement Dec-9-1986
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...     
4644846 Power steering system Feb-24-1987
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...     
4650377 Right angle drill Mar-17-1987
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...     
4653271 Boom crane centering Mar-31-1987
The present invention incorporates a free swing system into the hydraulic flow system of a boom crane in order to permit an operator to control the boom crane during the centering operation, which occurs immediately before and during the hoisting of a load. The free-swing system is incorporated into...     
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