US3840049A - Compact fluid motor control system with float position - Google Patents

Compact fluid motor control system with float position Download PDF

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Publication number
US3840049A
US3840049A US00386717A US38671773A US3840049A US 3840049 A US3840049 A US 3840049A US 00386717 A US00386717 A US 00386717A US 38671773 A US38671773 A US 38671773A US 3840049 A US3840049 A US 3840049A
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US
United States
Prior art keywords
valve
passage
pilot
motor
outlet
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Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US00386717A
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English (en)
Inventor
J Field
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Caterpillar Inc
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Caterpillar Tractor Co
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 Caterpillar Tractor Co filed Critical Caterpillar Tractor Co
Priority to US00386717A priority Critical patent/US3840049A/en
Priority to CA202,761A priority patent/CA996842A/en
Priority to JP49089555A priority patent/JPS5930922B2/ja
Priority to BE147355A priority patent/BE818565A/fr
Priority to GB3504074A priority patent/GB1427503A/en
Application granted granted Critical
Publication of US3840049A publication Critical patent/US3840049A/en
Assigned to CATERPILLAR INC., A CORP. OF DE. reassignment CATERPILLAR INC., A CORP. OF DE. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: CATERPILLAR TRACTOR CO., A CORP. OF CALIF.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/0401—Valve members; Fluid interconnections therefor
    • F15B13/0402—Valve members; Fluid interconnections therefor for linearly sliding valves, e.g. spool valves
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/86493—Multi-way valve unit
    • Y10T137/86574—Supply and exhaust
    • Y10T137/86582—Pilot-actuated
    • Y10T137/86606—Common to plural valve motor chambers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y10T137/87177—With bypass
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y10T137/87193—Pilot-actuated
    • Y10T137/87201—Common to plural valve motor chambers

Definitions

  • a control system for a fluid motor includes a motor direction control valve having a spool and means for selectively shifting the spool in response to fluid pressure signals from a manually operated pilot valve.
  • the directional valve has make-up valve means which automatically opens a bypass passage between the motor ports and fluid return passage when necessary to prevent cavitation of the motor due to an overrunning condition from external load force.
  • the spool of the pilot valve has four positions including one for each direction of motor motion, another for blocking any motor motion and a float position for deliberately interconnecting both motor ports and the fluid return passage so that the motor may move in either direction as determined by external load forces.
  • the spool of the larger and more costly directional valve need have only three positions as the float function is achieved by relieving the fluid pressure which normally biases one of the make-up valves towards the closed position.
  • Fluid-driven motors are usually controlled with a directional control valve wherein a spool or other valve member is shiftable between a Hold position at which the motor is stopped and another position for operating the motor in a first direction and still another position for reversing operation of the motor.
  • the motor moves a load which may on occasion tend to move faster than is provided for by the rate at which fluid is supplied to the motor through the directional control valve.
  • powered loaders of the type described in US. Pat. No. 3,599,813 and used to handle loose earth or other bulk material have a bucket carried on a pair of pivoting lift arms at the front of the vehicle wherein upward and downward movement of the bucket is typically provided for by fluid motors controlled by the vehicle operator.
  • fluid motors controlled by the vehicle operator.
  • gravitational force may tend to drive the fluid motors faster than is provided for by the supply of driving fluid.
  • motor cavitation will occur, with well known undesirable effects, unless corrective means are provided.
  • One such means of preventing cavitation are make-up valves which sense incipient cavitationand open to supplement the driving fluid flow to the motor with fluid:
  • the Float mode of operation is realized by manually initiating communication of the two ports of the motor with each other and with the return line to tank.
  • Providing of a Float position in the control system may also be. useful for purposes other than utilizing gravity force to speed movement of the load.
  • a loader as discussed above is often used to pick up loose material by pushing the bucket long the surface of the ground to receive such material. On uneven terrain, it is desirable that the bucket follow the contour of the ground and a Float position of the control system enables the bucket to do this.
  • a Float condition in fluid motor control systems has been provided for by means of directional control valve complications such as additional lands on the principal spool and appropriate passages in the valve body additional to those needed for establishing the other modes of motor operation discussed above.
  • This adds substantially to the length of the directional control valve spool and the complexity of the valve body.
  • Directional control valves are often a necessarily large assembly and these conventional provisions for a Float position add to the costs of such valves and substantially increase the space requirements for positioning the control system in a working context.
  • This invention is a compact and economically manufactured system for controlling a fluid motor wherein a Float mode of operation is to be provided for and wherein make-up valves are present to forestall cavitation.
  • the invention utilizes the make-up valve means for this purpose.
  • manual shifting of the operators pilot valve, which controls the directional valve, to the Float setting is arranged to relieve the pressure which normally biases a make-up valve towards a closed condition.
  • the make-up valve may then open to intercommunicate both ports of the motorto establish the Float condition.
  • FIG. 1 illustrates a fluid motor and control system therefor in accordance with the invention wherein valve bodies are shown in section and certain other components are shown schematically, the system being shown in the Hold or neutral position,
  • FIG. 2 is a section view of the pilot valve portion of FIG. 1 shown shifted to an Extend position at which the motor is caused to operate in a first direction,
  • FIG. 3 is a view of the pilot valve shown shifted to a Contract position at which the motor is caused to operate in an opposite direction
  • FIG. 4 is a section view showing the pilot valve shifted to the Float position.
  • a linear fluid motor 10 which is controlled by the present invention may be of conventional design and is therefore shown schematically in the drawing.
  • a pair of such motors 10 may, for example, be used to raise and lower the bucket of a loader vehicle of the kind previously discussed; however, it should be appreciated that the present control system is not limited to this particular usage nor is it limited to fluid motors of the linear kind, but is also applicable to rotary motors.
  • a linear motor of this form has two fluid ports 11 and 12 to which actuating fluid may be supplied. If actuating fluid is supplied to one such port 11, the motor retracts and fluid is discharged from the other port 12. If actuating fluid is supplied through port 12, the motor extends with fluid being discharged through the other port 11.
  • Pressurized fluid for driving the motor 10 is supplied by a pump 13 which draws fluid from a reservoir 14.
  • the outlet of pump 13 is communicated to an inlet port 16 of a directional control valve 17 by way of a conduit 15.
  • a relief valve 18 is connected between conduit and reservoir 14 to establish a maximum fluid pressure which can be transmitted to the motor and to return excess fluid directly to the reservoir.
  • Directional valve 17 has a first valve member or spool 19 located in a first bore 21 of a valve body 22 and the spool is movable axially to one of three positions which respectively constitute a Hold position at which motor 10 is stopped, a Retract position at which the motor is driven in the direction R indicated by arrow 23, and a third or Extend position at which the motor is driven in the opposite direction E as indicated by arrow 23.
  • Spool 19 of valve 17 is urged toward a centered position in bore 21, which constitutes the Hold position, by a pair of springs 24 and 24a situated in bore 21 at opposite ends of the spool.
  • Fluid inlet port 16 communicates by means of a passage 59 with an annular groove 61 at the center of bore 21.
  • Bore 21 has an additional groove 71 spaced to one side of input groove 61 and which is communicated with motor port 11 through a valve body passage 69, and conduit 67.
  • bore 21 has still another groove 63, on the opposite side of central input groove 61, that is communicated with the motor port 12 through a valve body passage 64 and conduit 66.
  • Bore 21 has still additional grooves 73 and 77 spaced outwardly from grooves 71 and 63 respectively, which are each communicated with the reservoir 14 by a drain passage 74 in the valve body and a drain conduit 76.
  • Spool 19 has a pair of grooves 62 and 72 situated on opposite sides of a central land 19' of the spool. Accordingly, when the spool 19 is at the above-described centered or Hold position, land 19' blocks driving fluid from both motor ports 11 and 12 while the end portions of the spool block communication between the two motor ports and drain passage 74. Thus, motor 10 is stopped and can neither extend nor retract. lf spool 19 is shifted to the left as viewed in FIG. 1, spool groove 62 communicates input port 16 with motor port 12 while spool groove 72 communicates motor port 11 with drain conduit 76 causing motor 10 to extend. Similarly, if spool 19 is shifted in the opposite direction, spool groove 72 transmits driving fluid from input port 16 to motor port 11 while groove 62 vents motor port 12 to drain causing the motor to retract.
  • Pilot valve 25 has a body with a bore 32 in which a spool 31 is disposed for axial movement by the operator between four positions which are the Extend, Hold, Retract and Float positions. Pilot valve 25 receives pressurized fluid from a second pump 26 which draws fluid from reservoir 14 and transmits the flow to an input port 28 of the pilot valve through a conduit 27. A second relief valve 29 is connected between conduit 27 and reservoir 14 to establish the basic pilot fluid pressure and to return excess output of pump 26 to reservoir 14.
  • a valve body passage 56 communicates the input port 28 of pilot valve 25 with an annular input groove 58 at bore 32. Additional grooves 34 and 43 of bore 32 are situated at opposite sides of groove 58 and connect with output passages 33 and 42 respectively of the pilot valve. Conduits 49 and 53 respectively connect output passages 33 and 42 with ports 51 and 54 respectively at opposite ends of bore 21 of the directional control valve 17.
  • Bore 32 of the pilot valve has additional grooves 36 and 45 spaced outwardly from grooves 34 and 43 respectively.
  • Groove 36 communicates with the reservoir 14 through a drain passage 37 while groove 45 connects with reservoir 14 through a passage 46.
  • Spool 31 has spaced-apart grooves 35 and 44 which in the Hold position of the spool communicate grooves 34 and 43 with drain grooves 36 and 45 respectively while the intervening portion of the spool blocks flow between input groove 58 and either of grooves 34 and 43.
  • spring chambers 52 and 55 of directional control valve 17 are vented and the directional control valve assumes the Hold position at which motor 10 is stopped.
  • pilot pressure from inlet port 28 is transmitted through grooves 58, 44 and 43 and passage 42 to conduit 53 while conduit 49 is opened to reservoir 14 through passage 33, grooves 34, 35 and 36 and passage 37.
  • this pressurizes spring chamber 55 of the directional control valve 17 while venting spring chamber 52.
  • Directional control valve spool 19 is thereby shifted to the hereinbefore described position at which motor 10 is caused to extend.
  • directional control valve 17 has a pair of cylindrical make-up valve members 78 and 79 disposed in additional bores 83 and 83a respectively of valve body 22 for axial movement therein.
  • a spring 86 urges valve member 78 against a seat 81 through which bore 83 connects with a short passage to groove 73 and thus with drain passage 74.
  • a spring 86a in bore 83a urges valve member 79 against a seat 82 through which the bore connects with a passage 75a to groove 77 and drain passage 74.
  • bores 83 and 83a respectively are normally blocked from communication with the drain passages by the valve members 78 and 79 but movement of either such valve member away from the associated seat 81 or 82 communicates the associated bore and motor port with drain passage 74.
  • valve member 78 and 79 which is exposed to the pressure within spring chambers 84 and 88 is greater than the area of shoulders 87 and 103 on which the pressure acts oppositely, the valve members normally remain closed in the presence of pressure rises in the associated flow passages 69 and 64 except under certain conditions to be hereinafter described.
  • Althrough passage 75 is connected to reservoir 14, the flow conduit 76 therebetween constitutes a sufficient flow restriction that adequate pressure is present in passage 75 to lift the valve member 78 from its seat once the pressure within spring chamber 84 has dropped sufficiently due to the incipient cavitation of motor 10.
  • valve member 78 When valve member 78 lifts from seat 81 as described above, the supply of driving fluid passing to motor port 11 through passage 69 is supplemented by additional fluid from drain passage 74 which fluid is the discharge flow from the other side of motor 10.
  • additional fluid from drain passage 74 which fluid is the discharge flow from the other side of motor 10.
  • the other make-up valve member 79 opens automatically to forestall cavitation during the Extend movement of motor 10 in a manner essentially similar to that described above for the make-up valve member 78.
  • pilot control valve 25 is shifted to the Float position as shown in FIG. 4, pilot pressure from inlet port 28 is transmitted to directional control valve 17 in the same manner as was previously described for the Retract position of the pilot valve which is closely adjacent the Float position.
  • pressure from inlet port 28 is transmitted to spring chamber 52 of directional control valve 17 through conduit 49 causing the spool 19' of the control valve to shift to the position at which driving fluid is supplied to the motor port 11 while motor port 12 is communicated with reservoir 14.
  • the Float position of pilot valve 25 communicates an additional groove 91 in pilot valve bore 32 with drain passage 37 through an additional groove 89 on pilot valve spool 31.
  • a passage 92 and conduit 94 connect groove 91 with a float valve 93 which is in turn connected to spring chambers 84 and 88 through separate conduits 95 and 99 respectively.
  • Float valve 93 is a two position valve having a body 104 and internal spool 106 biased by a spring 107 towards a position at which conduit 94 is communicated with conduit 99 while being blocked from conduit 95.
  • a pilot line 108 transmits fluid pressure from groove 58 of manual pilot valve 25 to one end of valve 93 to shift spool 106 to an alternate position whenever pump 26 is supplying fluid pressure. At this alternate position, depicted in FIG. 4, conduit 95 is communicated with conduit 94 while conduit 99 is blocked.
  • a control system for a fluid motor which has first and second motor ports (11, 12) wherein admission of pressurized fluid to said first motor port causes motor operation in one direction and admission of pressurized fluid to said second motor port causes motor operation in the opposite direction, the combination comprising:
  • a directional control valve (17) having an inlet passage (59) for receiving pressurized fluid and having a discharge passage (74) and first and second outlet passages (69, 64) for connection to said first and second motor ports respectively and having a valve member (19) movable between a first motor operating position at which fluid from said inlet is transmitted to said first outlet while said second outlet is communicated with said discharge passage and a second motor operating position at which fluid from said inlet is transmitted to said second outlet while said first outlet is communicated with said discharge passage, and further having pilot means (51, 54) for shifting said valve member between said positions in response to fluid pilot pressure signals,
  • make-up valve means disposed in a bypass passage (75) between at least one of said outlet passages of said directional control valve and said discharge passage and having a first make-up valve member (78) movable to close said bypass passage and having means forming a first chamber (84) wherein fluid pressure derived from said one outlet passage acts against said first make-up valve member to urge said first make-up valve member towards the position at which said bypass passage is closed, and
  • pilot valve (25) having an inlet passage (56) for receiving pressurized fluid and a discharge passage (37) and an outlet means (33) communicated with said pilot means of said directional control valve for transmitting said fluid pilot pressure signals thereto to shift said valve member of said directional control valve, said pilot valve further having a valve member (31) movable between a plurality of motor operating positions for selectively transmitting said pilot pressure signals to said directional control valve, and being further movable to a float position, said pilot valve having venting means (36, 91, 95) for communicating said first chamber of said make-up valve means with said pilot valve means discharge passage upon said movement of said pilot valve member to said float position.
  • pilot valve means has means (35, 49) for transmitting said pressure signals to said directional control valve pilot means to shift said valve member of said directional control valve to one of said motor operating positions thereof while said pilot valve member is at said float position thereof and said pilot valve means is communicating said first chamber of said directional control valve with said discharge passage of said pilot valve means.
  • said make-up valve means further comprises means forming a second bypass flow passage (a) between the other outlet passage (64) of said directional control valve and said discharge passage thereof, a second make-up valve member (79) movable to close said second bypass passage, means forming a second chamber (88) wherein fluid pressure derived from said other outlet passage acts against said second make-up valve member to urge said second make-up valve member to close said second bypass passage, a float valve (93) connected between said second chamber and said venting means, and means for opening said blocker valve in response to an unpressurized condition in said outlet means of said pilot valve means whereby said pilot valve means communicates said second chamber to said pilot valve discharge passage if said pilot valve member is at said float position and said fluid pilot pressure signal is absent.
  • a control system for a fluid motor having a first port to which pressurized fluid is supplied to drive said motor in a first direction and having a second port to which pressurized fluid is supplied to drive said motor in an opposite direction, the combination comprising:
  • a directional control valve having a valve body with an inlet passage for receiving the pressurized fluid and first and second outlet passages for connection to said first and second motor ports respectively and a discharge passage for discharging fluid, said valve body having a bore therein, said directional control valve having a first spool movable in said bore between a centered Hold position at which both of said outlet passages are blocked from said inlet passage and said discharge passage and having a first operating position at which said inlet passage is communicated with said first outlet passage while said second outlet passage is communicated to said discharge passage and having a second motor operating position at which said inlet passage is communicated with said second outlet passage while said first outlet passage is communicated with said discharge passage, and having spring means for urging said first spool towards said Hold position thereof; make-up valve means having means forming a first bypass passage between said first outlet passage and said discharge passage and having means forming a second bypass passage between said second outlet passage and said discharge passage and having first and" second make-up valve members disposed in said first and second bypass passages

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Multiple-Way Valves (AREA)
  • Reciprocating Pumps (AREA)
  • Fluid-Pressure Circuits (AREA)
US00386717A 1973-08-08 1973-08-08 Compact fluid motor control system with float position Expired - Lifetime US3840049A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US00386717A US3840049A (en) 1973-08-08 1973-08-08 Compact fluid motor control system with float position
CA202,761A CA996842A (en) 1973-08-08 1974-06-18 Compact fluid motor control system with float position
JP49089555A JPS5930922B2 (ja) 1973-08-08 1974-08-06 フロ−ト位置を備えたコンパクトな流体モ−タ制御システム
BE147355A BE818565A (fr) 1973-08-08 1974-08-07 Systeme de commande compact pour moteur a fluide avec position de flottement
GB3504074A GB1427503A (en) 1973-08-08 1974-08-08 Control system for fluid-driven motors

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00386717A US3840049A (en) 1973-08-08 1973-08-08 Compact fluid motor control system with float position

Publications (1)

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US3840049A true US3840049A (en) 1974-10-08

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US00386717A Expired - Lifetime US3840049A (en) 1973-08-08 1973-08-08 Compact fluid motor control system with float position

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US (1) US3840049A (fr)
JP (1) JPS5930922B2 (fr)
BE (1) BE818565A (fr)
CA (1) CA996842A (fr)
GB (1) GB1427503A (fr)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3960059A (en) * 1974-12-09 1976-06-01 Caterpillar Tractor Co. Fast exhaust circuit for hydraulic jacks
US4085920A (en) * 1976-11-15 1978-04-25 Caterpillar Tractor Co. Pilot control valve with servo means
WO1981003689A1 (fr) * 1980-06-16 1981-12-24 Caterpillar Tractor Co Systeme de vanne
WO1981003686A1 (fr) * 1980-06-16 1981-12-24 Caterpillar Tractor Co Soupape de reduction de pression avec tige flottante pour event d'appoint
WO1981003685A1 (fr) * 1980-06-16 1981-12-24 Caterpillar Tractor Co Soupape de reduction de pression pour l'abaissement d'une charge en cas de panne
US4320691A (en) * 1979-11-16 1982-03-23 Caterpillar Tractor Co. Hydraulic load lifting system with hydraulic surcharge to make up valve pilot lines
WO1982002229A1 (fr) * 1980-12-19 1982-07-08 Melocik Kurt B Commande d'abaissement dans le cas d'un moteur en panne
US4341243A (en) * 1980-06-16 1982-07-27 Caterpillar Tractor Co. Pressure reducing valve with floating stem for make-up vent
WO1982003663A1 (fr) * 1979-11-16 1982-10-28 Orcenith D Mcwilliams Systeme hydraulique de levage de charge pourvu d'une surcharge hydraulique au conduit pilote de vanne de compensation
US4362089A (en) * 1980-06-16 1982-12-07 Caterpillar Tractor Co. Valve system
US4392415A (en) * 1980-12-19 1983-07-12 Caterpillar Tractor Co. Control for dead engine lower
US4509406A (en) * 1980-06-16 1985-04-09 Caterpillar Tractor Co. Pressure reducing valve for dead engine lowering
JPH0272204A (ja) * 1989-03-17 1990-03-12 Komatsu Ltd バルブ
JPH0276908A (ja) * 1989-03-17 1990-03-16 Komatsu Ltd 圧油供給方法
JPH02225806A (ja) * 1989-03-17 1990-09-07 Komatsu Ltd 作業機シリンダの圧油供給制御方法
US20080149200A1 (en) * 2006-12-21 2008-06-26 M-I Llc Pressure-balanced choke system
WO2009005426A1 (fr) * 2007-07-02 2009-01-08 Parker Hannifin Ab Ensemble vanne fluidique
WO2015180824A1 (fr) * 2014-05-30 2015-12-03 Hydac Technology Gmbh Dispositif formant soupape, en particulier du type soupape anti-retour et procédé de fonctionnement d'un tel dispositif formant soupape

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5752426A (en) * 1909-04-04 1998-05-19 Komatsu Ltd. Pilot pressure operated directional control valve and an operating cylinder control apparatus
JPH04133024U (ja) * 1991-05-30 1992-12-10 エヌテイエヌ株式会社 転がり軸受

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2981287A (en) * 1958-11-14 1961-04-25 American Brake Shoe Co Pilot operated valve mechanism

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2981287A (en) * 1958-11-14 1961-04-25 American Brake Shoe Co Pilot operated valve mechanism

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2554892A1 (de) * 1974-12-09 1976-06-16 Caterpillar Tractor Co Rueckstromkreis fuer hydrozylinder
US3960059A (en) * 1974-12-09 1976-06-01 Caterpillar Tractor Co. Fast exhaust circuit for hydraulic jacks
US4085920A (en) * 1976-11-15 1978-04-25 Caterpillar Tractor Co. Pilot control valve with servo means
US4320691A (en) * 1979-11-16 1982-03-23 Caterpillar Tractor Co. Hydraulic load lifting system with hydraulic surcharge to make up valve pilot lines
WO1982003663A1 (fr) * 1979-11-16 1982-10-28 Orcenith D Mcwilliams Systeme hydraulique de levage de charge pourvu d'une surcharge hydraulique au conduit pilote de vanne de compensation
US4362089A (en) * 1980-06-16 1982-12-07 Caterpillar Tractor Co. Valve system
US4509406A (en) * 1980-06-16 1985-04-09 Caterpillar Tractor Co. Pressure reducing valve for dead engine lowering
WO1981003685A1 (fr) * 1980-06-16 1981-12-24 Caterpillar Tractor Co Soupape de reduction de pression pour l'abaissement d'une charge en cas de panne
US4341243A (en) * 1980-06-16 1982-07-27 Caterpillar Tractor Co. Pressure reducing valve with floating stem for make-up vent
WO1981003686A1 (fr) * 1980-06-16 1981-12-24 Caterpillar Tractor Co Soupape de reduction de pression avec tige flottante pour event d'appoint
WO1981003689A1 (fr) * 1980-06-16 1981-12-24 Caterpillar Tractor Co Systeme de vanne
US4392415A (en) * 1980-12-19 1983-07-12 Caterpillar Tractor Co. Control for dead engine lower
WO1982002229A1 (fr) * 1980-12-19 1982-07-08 Melocik Kurt B Commande d'abaissement dans le cas d'un moteur en panne
JPH0272204A (ja) * 1989-03-17 1990-03-12 Komatsu Ltd バルブ
JPH0276908A (ja) * 1989-03-17 1990-03-16 Komatsu Ltd 圧油供給方法
JPH02225806A (ja) * 1989-03-17 1990-09-07 Komatsu Ltd 作業機シリンダの圧油供給制御方法
US20080149200A1 (en) * 2006-12-21 2008-06-26 M-I Llc Pressure-balanced choke system
US8418989B2 (en) * 2006-12-21 2013-04-16 M-I L.L.C. Pressure-balanced choke system
WO2009005426A1 (fr) * 2007-07-02 2009-01-08 Parker Hannifin Ab Ensemble vanne fluidique
US8757196B2 (en) 2007-07-02 2014-06-24 Parker-Hannifin Corporation Fluid valve arrangement
WO2015180824A1 (fr) * 2014-05-30 2015-12-03 Hydac Technology Gmbh Dispositif formant soupape, en particulier du type soupape anti-retour et procédé de fonctionnement d'un tel dispositif formant soupape

Also Published As

Publication number Publication date
JPS5070789A (fr) 1975-06-12
JPS5930922B2 (ja) 1984-07-30
GB1427503A (en) 1976-03-10
BE818565A (fr) 1975-02-07
CA996842A (en) 1976-09-14

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AS Assignment

Owner name: CATERPILLAR INC., 100 N.E. ADAMS STREET, PEORIA, I

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905

Effective date: 19860515

Owner name: CATERPILLAR INC., A CORP. OF DE.,ILLINOIS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905

Effective date: 19860515