WO1982002230A1 - Systeme avec dispositif d'actionnement a force constante - Google Patents

Systeme avec dispositif d'actionnement a force constante Download PDF

Info

Publication number
WO1982002230A1
WO1982002230A1 PCT/US1980/001741 US8001741W WO8202230A1 WO 1982002230 A1 WO1982002230 A1 WO 1982002230A1 US 8001741 W US8001741 W US 8001741W WO 8202230 A1 WO8202230 A1 WO 8202230A1
Authority
WO
WIPO (PCT)
Prior art keywords
fluid
control valve
pilot
valve
actuator
Prior art date
Application number
PCT/US1980/001741
Other languages
English (en)
Inventor
Tractor Co Caterpillar
Original Assignee
Hall Lowell R
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hall Lowell R filed Critical Hall Lowell R
Priority to DE8181901579T priority Critical patent/DE3071525D1/de
Priority to JP50196681A priority patent/JPH0118285B2/ja
Priority to EP19810901579 priority patent/EP0067815B1/fr
Priority to PCT/US1980/001741 priority patent/WO1982002230A1/fr
Priority to BE0/206635A priority patent/BE891227A/fr
Publication of WO1982002230A1 publication Critical patent/WO1982002230A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20538—Type of pump constant capacity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • F15B2211/6054—Load sensing circuits having valve means between output member and the load sensing circuit using shuttle valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6058—Load sensing circuits with isolator valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76—Control of force or torque of the output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/78—Control of multiple output members
    • F15B2211/781—Control of multiple output members one or more output members having priority

Definitions

  • This invention is directed to pilot operated control valve systems and particularly those having an actuator requiring a continuous force on the actuator at the same time other work is being performed.
  • a fluid system has a fluid source, an actuator, a tank and a pilot operated control valve.
  • the pilot operated control valve has first and second ends and is movable between an actuated position and a neutral position. At the actuated position, the source communicates with the actuator and is blocked from a downstream control valve, and at the neutral position the fluid from the source is blocked from communication with the actuator and communicates with the downstream control valve through the pilot operated control valve.
  • a pilot control valve is connected to a source of pressurized pilot fluid and the first and second ends of the pilot operated control valve.
  • the pilot control valve is movable between a neutral position at which the source of pressurized pilot fluid is blocked from communication with the first and second ends, and an actuated position at which pressurized pilot fluid from the source is communicated with the first end establishing a differential pressure between the first and second ends.
  • a means modulatably reduces the pilot differential pressure between the first and second ends of the pilot operated control valve at the actuated position of the pilot operated control valve in response to the fluid pressure in the actuator reaching a predetermined level, so that the pilot operated control valve is controllably moved between the neutral and actuated positions to maintain the predetermined pressure level in the actuator and to pass fluid to the downstream control valve.
  • Fig. 1 is a schematic of an embodiment of the present invention.
  • Fig. 2 is a schematic of a portion of Fig. 1 illustrating a second embodiment of the present invention.
  • a fluid system is generally indicated by reference numeral 10 and includes a fluid source, such as, a pump 12 and a pilot operated control valve 14 connected to the pump 12 by a conduit 16.
  • An actuator 18 is connected to the pilot operated control valve 14 by a pair of conduits 20,22.
  • a control valve 24 is connected to the pilot operated control valve 14 by a conduit 26 and positioned downstream of the pilot operated control valve 14.
  • a tank 28 is connected to the pilot operated control valve 14 by a conduit 30.
  • the pilot operated control valve 14 is movable between a first or neutral position "A", a second or actuated position “B” and a third position “C".
  • the pilot operated control valve 14 is biased by centering springs 31 to the neutral position in a conventional manner.
  • the fluid source or pump 12 is blocked from communication with the actuator 18 and is in fluid communication with the downstream control valve 24.
  • the fluid source 12 is in communication with the actuator 18 through conduit 20 and the return flow in line 22 communicates with the control valve 24 through conduit 26.
  • the third position "C" the fluid source 12 is blocked from communication with the control valve 24 and is in communication with the actuator 28 through conduit 22.
  • the return flow in conduit 20 from actuator 18 returns to tank 28 through conduit 30.
  • a pilot control valve 32 is connected to a source of pressurized pilot fluid, such as a pilot pump 34, by a conduit 36.
  • the pilot control valve 32 is connected to first and second ends 38,40 of the pilot operated control valve 14 by first and second conduits 42,44 respectively.
  • a conduit 46 connects the pilot control valve 32 to the tank 28.
  • the pilot control valve 32 is movable between a first or neutral position "A'", a second, detented or actuated position "B'” and a third position “C'".
  • the first and second ends 38,40 of the pilot operated control valve 14 are blocked from communication with the source of pressurized pilot fluid 32 and are in communication with the tank 28.
  • the actuated position " B ' " the first end 38 is in communication with the source 34 of pressurized pilot fluid, and the second end 40 is open to the tank 28.
  • the second end 40 is in communication with the source 34 of pressurized pilot fluid and the first end 38 is open to the tank 28.
  • a differential pressure is established between the first and second ends 38,40 of the pilot operated control valve 14 by the difference in the pressures between the first and second ends 38,40.
  • a means 48 is provided for modulatably reducing the pilot differential pressure between the first and second ends 38,40 of the pilot operated control valve 14 in response to the fluid pressure in the actuator 18 reaching a predetermined level, so that the pilot operated control valve 14 is controllably moved between the neutral and actuated positions "A, B" to maintain the predetermined pressure level in the actuator 18 and to pass fluid to the downstream control valve 24.
  • the means 48 includes a two position valve 56 connected to the first end 38 and the actuator 18 and is adapted to controllably pass pressurized pilot fluid from the first end 38 in response to the actuator 18 reaching the predetermined level.
  • the fluid from the two position valve 56 is directed to the second end 40 of the pilot operated control valve 14 as hereinafter described.
  • the two position valve 56 is connected to the first end 38 by a conduit 54 and the first conduit 42.
  • a signal conduit 58 connects the two position valve 56 to the actuator 18.
  • the two position valve 56 is movable between a first position, as shown, at which the flow of pressurized pilot fluid through the conduit 54 is blocked and a second position at which the flow of pressurized pilot fluid is communicated through the conduit 54.
  • the two position valve 56 is biased to its first position by a spring 60 and to its second position in response to fluid pressure in the actuator 18 reaching a predetermined level.
  • the means 48 also includes a second means 50 for controllably communicating the pressurized pilot fluid to the second end 40.
  • the second means 50 includes a resolver valve 52 located in the second conduit 44, a third conduit 55 connected to the two position valve 56 and the resolver valve 52.
  • the resolver valve 52 is adapted to sense the higher of the pressurized pilot fluid in the second and third conduits 44,55 and deliver the higher pressure to the second end 40.
  • a conduit 62 having an orifice 64 located therein is connected to the third conduit 55 between the two position valve 56 and the resolver 52 and is connected to the tank 28.
  • a second embodiment is shown. It is noted that the same reference numerals of the first embodiment are used to designate similarly constructed counterpart elements of this embodiment.
  • the resolver valve 52, the two position valve 56, conduit 54, third conduit 55, conduit 62 and orifice 64 are deleted.
  • a two position valve 66 is connected to the pilot control valve 32 by conduit 42A and to the first end 38 of the pilot operated control valve 14 by a conduit 42B.
  • the two position valve 66 is also connected to the tank 28 by a conduit 68 and to the actuator 18 by signal conduit 58.
  • the two position valve 66 is movable between a first position, as shown, at which the presurized pilot fluid from the source 34 is directed to the first end 38, and a second position at which the pressurized pilot fluid is blocked from communication with the first end 38 and the first end 38 is communicated to the tank 28.
  • the two position valve. 66 is biased to the first position by a spring 70 and biased to the second position in response to fluid pressure in the actuator 18 reaching a predetermined level.
  • the present invention has particular utility in hydraulic systems that require having one actuator held under a constant force during operation of the system, such as, when lifting and/or transporting several logs in a log fork having clamping arms to hold the logs.
  • an operator moves the pilot control valve 32 to the second, detented position "B'" directing pressurized pilot fluid to the first end 38 of the pilot operated control valve 14 which establishes a differential pressure between the first and second ends 38,40, thus shifting the pilot operated control valve 14 to the second position "B".
  • Fluid from the source 12 is directed to the actuator 18 by conduit 20 to close the clamping arms, not shown.
  • the return flow by conduit 22 from the actuator 18 is passed to the downstream control valve 24 by line 26.
  • the pressure in the actuator 18 will increase.
  • the two position valve 56 sensing the pressure through conduit 58, will move towards the second position against the bias of spring 60.
  • the pressurized pilot fluid 34 from the first conduit 42 is modulatably directed through the two position valve 56 and the resolver valve 52 to the second end 40 of the pilot operated control valve 14.
  • the centering springs 31 moves the pilot operated control valve 14 towards the neutral position "B" thus allowing fluid from the source 12 to pass to the downstream control valve 24.
  • the two position valve 56 moves towards the first position and reduces the flow of pressurized pilot fluid 34 to the second end 40.
  • the pressurized fluid in the second end 40 is reduced by the flow of fluid across orifice 64 to tank 28.
  • the higher pressure on the first end 38 moves the pilot operated control valve 14 towards the second position "B" to direct fluid from the source 12 to the actuator 18.
  • the pilot operated control valve 14 will automatically move to a position to maintain the pressure in the actuator 18 at the predetermined pressure level until the pilot control valve 32 is returned to its neutral position "A'".
  • the second embodiment shown in Fig. 2 operates in a similar manner as the embodiment in Fig. 1 to automatically move the pilot operated control valve 14 to a position to maintain a predetermined pressure level in the actuator 18.
  • the two position valve 66 modulatably controls, in response to the pressure in actuator 18, the pressurized pilot fluid acting on the first end 38.
  • the two position valve sensing the pressure through conduit 58 moves towards the second position against the bias of spring 70.
  • the force of the centering springs 31 acting against the reduced differential pressure moves the pilot operated control valve 14 towards the neutral position "B" as in Fig. 1.
  • an actuator can be maintained at a predetermined pressure while still providing flow to a downstream valve.
  • the pilot operated control valve would automatically shift to its actuated position to supply the flow.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

Un mecanisme de commande (48) est concu pour maintenir de maniere controlee une force constante sur un dispositif d'actionnement (18) et pour permettre l'ecoulement d'un fluide vers une vanne de commande aval (24) en commandant une pression differentielle pilote entre une premiere et une seconde extremites (38, 40) d'une vanne de commande (14) fonctionnant par le pilote. Une vanne a deux positions (56, 66) agissant en reponse a un niveau de pression predetermine dans le dispositif d'actionnement (18) commande de maniere modulee l'ecoulement du fluide pilote pressurise vers la vanne de commande (14) fonctionnant par le pilote pour positionner cette derniere. Ceci permet de maintenir la pression d'un dispositif d'actionnement (18) a un niveau de pression predetermine et fait passer l'ecoulement de fluide en exces depuis une source (12) vers la vanne de commande aval (24).
PCT/US1980/001741 1980-12-24 1980-12-24 Systeme avec dispositif d'actionnement a force constante WO1982002230A1 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
DE8181901579T DE3071525D1 (en) 1980-12-24 1980-12-24 System with constant force actuator
JP50196681A JPH0118285B2 (fr) 1980-12-24 1980-12-24
EP19810901579 EP0067815B1 (fr) 1980-12-24 1980-12-24 Systeme avec dispositif d'actionnement a force constante
PCT/US1980/001741 WO1982002230A1 (fr) 1980-12-24 1980-12-24 Systeme avec dispositif d'actionnement a force constante
BE0/206635A BE891227A (fr) 1980-12-24 1981-11-24 Systeme comprenant un verin a force constante

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
WOUS80/01741801224 1980-12-24
PCT/US1980/001741 WO1982002230A1 (fr) 1980-12-24 1980-12-24 Systeme avec dispositif d'actionnement a force constante

Publications (1)

Publication Number Publication Date
WO1982002230A1 true WO1982002230A1 (fr) 1982-07-08

Family

ID=22154709

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1980/001741 WO1982002230A1 (fr) 1980-12-24 1980-12-24 Systeme avec dispositif d'actionnement a force constante

Country Status (5)

Country Link
EP (1) EP0067815B1 (fr)
JP (1) JPH0118285B2 (fr)
BE (1) BE891227A (fr)
DE (1) DE3071525D1 (fr)
WO (1) WO1982002230A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5809862A (en) * 1995-08-04 1998-09-22 Dallman; Jimmie J. Flotation control system

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2931389A (en) * 1956-04-18 1960-04-05 Moog Servocontrols Inc Servo valve producing output differential pressure independent of flow rate
US3720059A (en) * 1969-10-15 1973-03-13 Linde Ag Hydraulic system and valve therefor
US3799200A (en) * 1972-06-12 1974-03-26 Gardner Denver Co Flow and pressure regulating control for hydraulic motors
US4041983A (en) * 1975-07-09 1977-08-16 Caterpillar Tractor Co. Pressure controlled swing valve with safety feature

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE365486B (fr) * 1972-08-14 1974-03-25 Tico Ab

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2931389A (en) * 1956-04-18 1960-04-05 Moog Servocontrols Inc Servo valve producing output differential pressure independent of flow rate
US3720059A (en) * 1969-10-15 1973-03-13 Linde Ag Hydraulic system and valve therefor
US3799200A (en) * 1972-06-12 1974-03-26 Gardner Denver Co Flow and pressure regulating control for hydraulic motors
US4041983A (en) * 1975-07-09 1977-08-16 Caterpillar Tractor Co. Pressure controlled swing valve with safety feature

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0067815A4 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5809862A (en) * 1995-08-04 1998-09-22 Dallman; Jimmie J. Flotation control system

Also Published As

Publication number Publication date
JPS57502013A (fr) 1982-11-11
DE3071525D1 (en) 1986-05-07
BE891227A (fr) 1982-03-16
JPH0118285B2 (fr) 1989-04-05
EP0067815A4 (fr) 1984-04-04
EP0067815A1 (fr) 1982-12-29
EP0067815B1 (fr) 1986-04-02

Similar Documents

Publication Publication Date Title
US4372193A (en) System with constant force actuator
EP0545925B1 (fr) Soupape de compensation de pression et de controle de charge
US5568759A (en) Hydraulic circuit having dual electrohydraulic control valves
EP0621925B1 (fr) Systeme de regulation hydraulique possedant des vannes automatiques a bague et a champignon
US4024797A (en) Spring centered balanced resolver valve
WO1991017363A1 (fr) Systeme hydraulique detecteur de charge
EP0489817B1 (fr) Circuit de duplication de la pression de charge
US3872773A (en) Position controlling
US4509406A (en) Pressure reducing valve for dead engine lowering
GB2033015A (en) Hydraulic system
US5934406A (en) Jerk control valve for pilot operated steering system
GB1031258A (en) Hydraulic system
US4215622A (en) Hydraulic control system
US5060475A (en) Pilot control circuit for load sensing hydraulic systems
US4341243A (en) Pressure reducing valve with floating stem for make-up vent
EP0067815B1 (fr) Systeme avec dispositif d'actionnement a force constante
US4121501A (en) Flow combining system for dual pumps
US2977971A (en) Fluid distribution system and valves therefor
GB2234297A (en) Load-independent control device for hydraulic consuming devices
EP0056369B1 (fr) Soupape de reduction de pression pour l'abaissement d'une charge en cas de panne
GB1571932A (en) Dither for a hydraulic system
EP0056024B1 (fr) Soupape de reduction de pression avec tige flottante pour event d'appoint
WO1993013319A1 (fr) Systeme de commande hydraulique pour deux actionneurs independants
GB1437424A (en) Hydrostatic transmission
US4913191A (en) Directional control valve

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 1981901579

Country of ref document: EP

AK Designated states

Designated state(s): BR JP US

AL Designated countries for regional patents

Designated state(s): AT CH DE FR GB NL SE

WWP Wipo information: published in national office

Ref document number: 1981901579

Country of ref document: EP

WWG Wipo information: grant in national office

Ref document number: 1981901579

Country of ref document: EP