US3792792A - Hydraulic self-leveling device for a loader bucket - Google Patents

Hydraulic self-leveling device for a loader bucket Download PDF

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Publication number
US3792792A
US3792792A US00249604A US3792792DA US3792792A US 3792792 A US3792792 A US 3792792A US 00249604 A US00249604 A US 00249604A US 3792792D A US3792792D A US 3792792DA US 3792792 A US3792792 A US 3792792A
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United States
Prior art keywords
port
fluid
spool
cylinder
bucket
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Expired - Lifetime
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US00249604A
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English (en)
Inventor
R Bromberek
G Holloway
R Oliver
R Yeh
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Komatsu America International Co
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International Harverster Corp
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Assigned to DRESSER INDUSTRIES, INC., A CORP. OF DEL. reassignment DRESSER INDUSTRIES, INC., A CORP. OF DEL. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INTERNATIONAL HARVESTER COMPANY
Assigned to KOMATSU DRESSER COMPANY, E. SUNNYSIDE 7TH ST., LIBERTYVILLE, IL., A GENERAL PARTNERSHIP UNDER THE UNIFORM PARTNERSHIP ACT OF THE STATE OF DE reassignment KOMATSU DRESSER COMPANY, E. SUNNYSIDE 7TH ST., LIBERTYVILLE, IL., A GENERAL PARTNERSHIP UNDER THE UNIFORM PARTNERSHIP ACT OF THE STATE OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: DRESSER FINANCE CORPORATION, A CORP. OF DE.
Assigned to DRESSER FINANCE CORPORATION, DALLAS, TX., A DE CORP. reassignment DRESSER FINANCE CORPORATION, DALLAS, TX., A DE CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: DRESSER INDUSTRIES, INC.
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Expired - Lifetime legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
    • E02F3/431—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like
    • E02F3/432—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like for keeping the bucket in a predetermined position or attitude
    • E02F3/433—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like for keeping the bucket in a predetermined position or attitude horizontal, e.g. self-levelling

Definitions

  • ABSTRACT A mechanically actuated single valve which has a sequence of opening and closing port connections controlled by a timed spool.
  • the timing of the spool and arrangement of the hydraulic circuitry is such that high pressure fluid can be delivered to both sides of a hydraulic cylinder, with no movement thereof because of the balance of forces on the cylinder.
  • This invention relates to material loaders including a prime mover and a loader frame having a boom and a bucket, and more particularly, to a self-leveling device for maintaining the bucket in a constant position relative to the ground during segments of the working cycle.
  • assemblies of this nature comprise a self-propelled vehicle or support, the front end of which mounts a boom structure that is hydraulically actuated in a plane perpendicular to that of the vehicle.
  • the boom of a front end loader for example, carries a bucket which engages material as the tractor is driven forwardly, etc. As the boom is raised, the bucket containing the material must be reoriented in relationship to the ground or tilted back such that the maximum amount of material be maintained therein.
  • the vehicle operator during this series of maneuvers, is required to steer the vehicle, actuate the boom and maintain the bucket in the proper tiltback orientation as the boom is raised.
  • the self-leveling valve means is basically a two-position design with an intermediate throttling range.
  • a sequence of opening and closing port connections are controlled by critical timing in the valve design, In its neutral position, the inlet pressure port of the valve is blocked off from the head side of the bucket cylinder. At this time, communication between the rod and the head side of the bucket cylinder is also blocked off at the valve.
  • the mechanical linkage connected to the bucket actuates the self-leveling valve means, causing high pressure fluid to be fed through the inlet port to the head side of the bucket cylinder means. Further actuation of the self-leveling valve opens a regenerative exit orifice for the fluid in the rod side of the cylinder, to be recirculated to the head side. This action causes the bucket cylinder to extend and level the bucket as long as the boom is raising within a given boom height range. When the boom stops, the feedback signal will dissipate, the spool will shift to a equilibrium position shutting off the exit ports in the valve.
  • an object of this invention is to provide an efficient economical self-leveling device for maintaining the proper bucket/ground orientation during the material handling cycle.
  • Another object of this invention is to provide a hydraulic self-leveling device which prevents cavitation of the bucket cylinder during dumping of the bucket contents.
  • Yet another object of this invention is to provide a self-leveling assembly which can be adjusted such that self-leveling becomes automatic at various boom heights.
  • Another object of this invention is to provide a selfleveling assembly which when in the self leveling range can be manually overridden, but only into a dump positron.
  • Still another object of this invention is to provide a spool-type valve assembly for controlling the actuation of the bucket hydraulic cylinders automatically.
  • Another object of this invention is to provide a selfleveling system which provides improved self-leveling of the loader bucket regardless of bucket payload or engine RPM.
  • Yet another object of this invention is to provide a self-leveling valve. which in a neutral self-leveled position has no significant dead band between signal input and response.
  • FIG. 1 is a side elevation of almaterial loader of the type mentioned with parts of the mechanism indicated;
  • FIG. 2 is a cross section view' of the self-leveling valve
  • FIG. 3 is a diagram showing the hydraulic circuitry involved in this invention.
  • the material loader 106 includes a support vehicle means 108 and a boom means 110 upon which is mounted a bucket means 112 and a double. acting hydraulic cylinder means 20.
  • a mechanical feedback linkage means 46 communicates movement of bucket means 112 to leveling assembly means 10.
  • the leveling assembly means 10 herein shown is a one-spool valve assembly comprising a housing means 12 provided with a longitudinally extending bore means 14 in which the spool means 16 horizontally reciprocates.
  • the manual control means 18 is cut in or cut out of the hydraulic circuitry whereby control of a head side working double acting'fluid cylinder means 20 is assumed by valve assembly means 10.
  • longitudinally extending bore means 14 is intersected at axially spaced intervals by first and second port means 22 and 24 and third, fourth and fifth port means 26, 28 and 30.
  • first and second port means 22 and 24 and third, fourth and fifth port means 26, 28 and 30.
  • a power driven hydraulic pressure source such as a pump 32 has its pressure side connected to manual control valve means 18 by line 34 and to valve means by line 36.
  • valve 18 is of any conventional open-center type having a high pressure outlet means 38 and a dump line means 40 whereby fluid is selectively supplied to and exhausted from the opposite sides of hydraulic cylinder means 20.
  • system A which includes line means 38 and 38a assumes the function of system B which includes dump line 40 and vice versa. This occurs simply upon moving the control spool located therein.
  • When being actuated such a dump command is given bucket 112, high pressure fluid passes through A system, and return fluid to dump through B system.
  • a and B systems perform the reversed function when a rollback command is given.
  • spool means 16 is in a neutral position, that is, high pressure fluid from manual control valve means 18, via system A and line 38, is passing directiy through spool valve means 10 to headside 24 of hydraulic cylinder means 20.
  • spool means 16 is moved to the left from its neutral position by mechanical lever means 42 into a working position, high pressure fluid lines 36 and 36a are opened and high pressure fluid line means 38 and'38a are closed.
  • the sensitivity of the mechanical feed-back linkage means 46, of which lever 42 is the terminus must be designed such that it is compatible with the loader means 106 geometry and the characteristics of valve means 10.
  • such mechanical linkages are well known in the art and that we, in no way, intend to limit the claims and scope of the invention herein disclosed.
  • Mechanical input shaft means 42 passes through a plug means 44 which closes off bore means 14 against loss of high pressure fluid. Seal means 41, cutting off leaks, is provided between plug means 44 and end 48 of housing means 12.
  • a second seal means 50 serves the same function between input shaft 42 and plug bore means 52.
  • a shoulder means 54 on input shaft means 42 functions such that when in a neutral state, a seating means is provided to limit the rightward travel of input shaft 42.
  • spring means 60 maintains the fluid directing assemblage to the right, that is, keeps shoulder means 54 in a seated arrangement and spool 16 in a neutral position.
  • Spring centering mechanism 60 has a first end section means 65 positioned in a counterbore means 62 of end 64 of spool means 16. The second end means 63 thereof, is positioned in a second counterbore 66 located in plug means 68. Plug means 68 closes off second end 70 of bore means 14, and a seal is formed with second end 72 of housing 12.
  • spring means 60 yieldably h-olds'spool meansl6 in a'neutral position as shown in FIG 2. ln this neutral position, high pressure fluid from manual control valve means 18 freely passes through high pressure line 38, via first port 22 and third port 26, to the head side 21 of hydraulic cylinder means 20.
  • a longitudinally extending channel means 74 extends directly through plug means 68 and spool means 16, groove means 76 being provided at end 56 of spool 16 allowing entrapped fluid to drain therefrom. Thus, any, fluid which might accumulate in front of plug 44 because of leakage or otherwise may be removed.
  • the spool means 16 is provided with a series of land means 78, 82, 84 and 86. Separating said axial spaced land means are groove means 88, and 92. Correspondingly adjacent to said spool groove means and land means are a plurality of spool bore groove passage means 94, 96, 98, and 102. As is apparent from a consideration of FIG. 2, passage means 94, 96, 98, 100 and 102 are extensions of the correspondingly adjacent port means.
  • third port means 26 will be closed by land means 86 and the groove means 88 will place fifth port 30 and second port 24, via high pressure line 36, in direct fluid communication with pump 32.
  • high pressure fluid will flow through self-leveling means 10 to fluid cylinder means 20.
  • grooved means 90 opens fourth port 28 such that low pressure hydraulic fluid from hydraulic cylinder means 20 passes into passage means 96 and therefrom, via groove means 88, back into the fifth port means 30.
  • the work cycle begins with the positioning of the boom in a float position and the filling of the bucket.
  • the boom means 106 as shown in FIG. I
  • the amount of leveling necessary to keep the bucket 112 properly aligned increases.
  • bucket orientation problems are minor.
  • the bucket is rolled back such that it dumps, the load falls in front of the vehicle and not on the operator.
  • the boom is progressively raised, dependent upon the loader system assembly, the dangers inherent with roll back increase.
  • an automatic self-leveling means performs the leveling function if the bucket is tipped into a rollback position.
  • the mechanical linkage means 42 causes the engagement of the leveling valve means 10 to move the bucket from a rollback position into a level position.
  • rollback via manual means 18 is prevented due to a balance of cylinder forces 20.
  • the selfleveling valve 10 assumes a static or equilibrium position. ln this steady state position,-spool'means l6 relocates such that land means 82 just contacts lip means 98. That is, leading edge 83 just contacts lip means 85.
  • the timing of spool means 16 is so designed that when the above relationship exists, port means 26 and 30 are open sufficiently to balance the hydraulic cylinder if a rollback command is given. It should be noted, however, that fifth port means 30 is open more than third port means 26 for reasons which will hereafter be explained.
  • FIG. 3 wherein is shown a diagrammatic view of FIG. 2, the self-leveling valve being in an equilibrium or static position as described above. This position can best be described by steady state antirollback and stability equation:
  • .4 and K are respectively the orifice area and flow coefficient of third port means 26.
  • a and K are respectively the orifice area and flow coefficient of fifth port means 30.
  • the operator can actuate manual control means 18 such that a rollback command can be given to bucket means 112. That is, high pressure fluid can be directed through B and line means 40 into the rod side of hydraulic cylinder means 20, A through line means 38 being opened to dump.
  • the anti-rollback feature of self-leveling valve means 10 is based on the timing arrangement of spool means 16, that is, the timing is such that the forces on both sides of hydraulic cylinder 20 remain balanced when the rollback command is given manually.
  • P A and A are known values and P is the unknown for which the equation must be solved.
  • P can be determined by control of the values A and A or the orifice sizes of third port means 26 and fifth port means 30 when spool 16 is in a static position.
  • a further advantage flowing from the disclosed structure is lack of an appreciable dead zone at the top of the cycle. That is, the relationship of edges 83 and 85 is such that only a very small amount of movement of spool 16 is necessary to cause leveling.
  • a second dead zone will exist from the time the mechanical linkage actuates spool 16 until spool 16 obtains a self-leveling position. This second dead zone is, however, not nearly as critical as the first since adjustments can be made for this.
  • the oil required to move the bucket cylinder during self-leveling includes the displaced cylinder oil as well as the pump supply. Therefore, the lift time of the boom is affected very little during normal operation and the delay time to energize the leveling circuit is greatly reduced.
  • a further aspect of the timing of spool means 16 involves the identical feathering or metering notch means 81, 81a, and 81b which are designed to handle the flow requirements during the leveling operation without the spool moving out of their range. Without such feathering means upon opening of the corresponding land means, a pressure peak would result causing the bucket to jump or chatter, etc.
  • the notch means 81 which is identical to the others, comprises a generally V like indentation on the surface of the land extending horizontally from the face means 118 of groove means 88.
  • the timing arrangement of the notch means 81, 81a and 81b is such that the working side of hydraulic cylinder means 20 is pressurized before the exit port side opens. That is, as shown in FIG.
  • port means 30 opens prior to port means 26, thereby avoiding cavitation.
  • the feathering is timed such that antirollback is achieved due to two orifices in series creating an intermediate pressure to the head side of the cylinder.
  • the cylinder forces balance if a rollback command is given during the leveling cycle and the command is nulified. Additionally the dead zone between the equilibrium or static position and the working position is minimized response thereby being immediate.
  • a valve assembly which automatically cuts out manual control and governs controlling actuation of the double acting fluid cylinder means of a work bucket to achieve leveling thereof upon boom raising comprismg:
  • a fluid pump means pumping high pressure hydraulic fluid
  • a valve means including:
  • a housing means having a longitudinally extending bore means intersected at axially spaced intervals therealong by first, second, third, fourth and fifth port means, said first port means being connected to said manual fluid direction control means and said second port means being connected directly to said fluid pump means, said third and fifth port means being connected to said double acting fluid cylinder means on the head side thereof and said fourth port means being connected to said double acting fluid cylinder means on the rod side: thereof;
  • valve spool means axially movable in said bore means from a neutral position blocking fluid from all port means except said first means and said third means, to a working position wherein first and third port means are closed and second, fourth and fifth port means are open, and an equilibrium position wherein only said fourth port means is closed;
  • a link means connected to said valve spool means for transferring force from said mechanical linkage means to shift said spool means whereby said manual fluid direction means is cut out and said bucket is automatically maintained level to ground.
  • valve assembly of claim 1 wherein said spool means has a timed feathering means whereby said third and fifth port means in series create an intermediate pressure to the head side of said cylinder means such that cylinder forces are balanced.
  • valve assembly of claim 2 wherein said spool means has a plurality of axially spaced apart circumferentially extending groove means whereby communicating said first and third port means, and said second, fourth and fifth port means.
  • valve assembly of claim 3 wherein said spool means has a plurality of axially spaced apart circumferentially extending land means attenuatively covering and opening said corresponding adjacent port means.
  • valve assembly of claim 4 wherein said plurality of axially spaced apart circumferentially extending land means include a first, second and third land means, said first means covering said first and third port means, said second covering said fourth port means and said third covering said second and fifth port means.
  • said bore means has a plurality of spaced apart circumferentially extending groove means positioned adjacent said inlet port means; and said land means have feathered edge means.
  • valve assembly of claim 6 wherein said longitudinally extending bore means has first and second end means each being provided with first and second stop means respectively, said first stop means carrying by said mechanical link means and said second stop means has a channel means therein.
  • a valve assembly which automatically cuts out manual control and governs controlling actuation of the double acting fluid cylinder means of a work bucket to achieve leveling thereof upon boom raising comprising:
  • a valvemeans including:
  • a spool means moving between a neutral, working, and equilibrium position, wherein said spool means has feathering means whereby forces on said cylinder in an equilibrium or self leveling position are described by the formula: KXA JKK 14, A P /P, wherein: A and K are respectively the orifice area and flow coefficient of the fifth port means, A and K are respectively the orifice area and flow coefficient of the third port means, P is the pressure on the head side of the cylinder means and P is the pressure on the rod side.
  • a non-leveling fluid conduit means communicating said manual control means and first end of said double acting fluid cylinder means when said spool means is in a neutral position
  • a leveling fluid conduit means including an inlet fluid means communicating said fluid pump means and a first end of said double acting fluid cylinder means, and whereby when said bucket has been leveled said leveling fluid conduit means prevents rollback thereof;
  • an anti-cavitation fluid conduit means connecting said inlet fluid means and the discharge outlet of said double acting fluid cylinder means when said spool means is in a working position.
  • a valve assembly which automatically cuts out manual control and governs controlling actuation of the double acting fluid cylinder means of a work bucket to achieve leveling thereof upon boom raising comprising:
  • a housing means having a longitudinally extending bore means intersected at axially spaced intervals therealong by first, second, third, fourth and fifth port means;
  • a spool means carried in said bore moving between a neutral, working, and equilibrium position, wherein said equilibrium position is described by the equation:
  • P is the pressure on the rod side.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Operation Control Of Excavators (AREA)
  • Fluid-Pressure Circuits (AREA)
US00249604A 1972-05-02 1972-05-02 Hydraulic self-leveling device for a loader bucket Expired - Lifetime US3792792A (en)

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US24960472A 1972-05-02 1972-05-02

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US00249604A Expired - Lifetime US3792792A (en) 1972-05-02 1972-05-02 Hydraulic self-leveling device for a loader bucket

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US (1) US3792792A (enrdf_load_stackoverflow)
JP (1) JPS5749689B2 (enrdf_load_stackoverflow)
CA (1) CA968254A (enrdf_load_stackoverflow)
FR (1) FR2183004B1 (enrdf_load_stackoverflow)
GB (1) GB1426357A (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4372729A (en) * 1980-07-21 1983-02-08 Veda, Inc. Tilt control
US4452559A (en) * 1982-09-03 1984-06-05 J.I. Case Company Attachment assembly for bellcrank arm
US4687406A (en) * 1985-04-20 1987-08-18 Kombilift Limited Load lifting apparatus with overturning prevention means
US10047502B2 (en) * 2015-12-10 2018-08-14 Caterpillar Inc. System and method for controlling a work implement of a machine
US11168712B2 (en) 2019-02-22 2021-11-09 Clark Equipment Company Hydraulic leveling circuit for power machines

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04127091U (ja) * 1991-05-10 1992-11-19 三菱重工業株式会社 船内溶接部検査装置
CN112482462B (zh) * 2020-11-16 2022-05-27 广西柳工机械股份有限公司 装载机铲装准备控制方法和系统

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3521781A (en) * 1968-09-26 1970-07-28 Case Co J I Anti-rollback mechanism
US3568869A (en) * 1969-01-09 1971-03-09 Case Co J I Antirollback mechanism
US3695474A (en) * 1970-08-05 1972-10-03 Case Co J I Hydraulic control linkage for implement

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2731162A (en) * 1953-11-19 1956-01-17 Superior Separator Company Loader with self-leveling carrier
US2883077A (en) * 1956-02-23 1959-04-21 John S Pilch Bucket control for loader or the like
GB783846A (en) * 1956-05-22 1957-10-02 Max Knobel Improved bucket scoop loader
US3009590A (en) * 1957-05-29 1961-11-21 Hough Co Frank Tractor loader
US2914202A (en) * 1957-09-16 1959-11-24 Mixermobile Manufacturers Inc Loader vehicle
US3032215A (en) * 1958-08-29 1962-05-01 Deere & Co Loader bucket leveling control
DE1100555B (de) * 1958-10-16 1961-02-23 Meiller Fahrzeuge Hydraulische Steuervorrichtung zum Parallelhalten der Ladeschaufel von UEberkopfladern
US3120314A (en) * 1960-10-11 1964-02-04 Massey Ferguson Inc Self-leveling valve attachment for loaders
US3179120A (en) * 1963-05-24 1965-04-20 Koehring Co Proportional flow divider
SE322469B (enrdf_load_stackoverflow) * 1968-06-06 1970-04-06 Ilsbo Ind Ab

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3521781A (en) * 1968-09-26 1970-07-28 Case Co J I Anti-rollback mechanism
US3568869A (en) * 1969-01-09 1971-03-09 Case Co J I Antirollback mechanism
US3695474A (en) * 1970-08-05 1972-10-03 Case Co J I Hydraulic control linkage for implement

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4372729A (en) * 1980-07-21 1983-02-08 Veda, Inc. Tilt control
US4452559A (en) * 1982-09-03 1984-06-05 J.I. Case Company Attachment assembly for bellcrank arm
US4687406A (en) * 1985-04-20 1987-08-18 Kombilift Limited Load lifting apparatus with overturning prevention means
US10047502B2 (en) * 2015-12-10 2018-08-14 Caterpillar Inc. System and method for controlling a work implement of a machine
US11168712B2 (en) 2019-02-22 2021-11-09 Clark Equipment Company Hydraulic leveling circuit for power machines

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Publication number Publication date
GB1426357A (en) 1976-02-25
CA968254A (en) 1975-05-27
JPS5749689B2 (enrdf_load_stackoverflow) 1982-10-23
JPS4921902A (enrdf_load_stackoverflow) 1974-02-26
FR2183004B1 (enrdf_load_stackoverflow) 1978-06-23
FR2183004A1 (enrdf_load_stackoverflow) 1973-12-14

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Owner name: DRESSER INDUSTRIES, INC., A CORP. OF DEL., STATELE

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Effective date: 19821101

Owner name: DRESSER INDUSTRIES, INC., A CORP. OF DEL.

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Effective date: 19821101

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Owner name: KOMATSU DRESSER COMPANY, E. SUNNYSIDE 7TH ST., LIB

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:DRESSER FINANCE CORPORATION, A CORP. OF DE.;REEL/FRAME:004994/0077

Effective date: 19880901

Owner name: DRESSER FINANCE CORPORATION, DALLAS, TX., A DE COR

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:DRESSER INDUSTRIES, INC.;REEL/FRAME:004994/0061

Effective date: 19880831