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Publication numberUS3856163 A
Publication typeGrant
Publication dateDec 24, 1974
Filing dateDec 14, 1973
Priority dateJul 17, 1972
Publication numberUS 3856163 A, US 3856163A, US-A-3856163, US3856163 A, US3856163A
InventorsSeaberg D
Original AssigneeCase Co J I
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of using a hydraulic leveling circuit on an implement
US 3856163 A
Abstract
The disclosure relates to a hydraulic circuit for a vehicle having a boom pivoted thereon by a boom ram and a bucket pivoted on the boom by a bucket ram. The hydraulic circuit includes a main pump that supplies fluid under pressure from a reservoir to the boom and bucket rams through control vales. An auxiliary circuit supplies fluid from the reservoir to the bucket ram to maintain the material handling unit at a predetermined attitude with respect to the reference plane and the auxiliary circuit includes a pump that is driven by the flow of fluid between the boom control valve and the boom ram.
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Description  (OCR text may contain errors)

United Stat es Patent 191 Seaberg [4 1 Dec. 24, 1974 METHOD OF USING A HYDRAULIC LEVELING CIRCUIT ON AN IMPLEMENT [62] Division oiSer. No. 272,365, July 17, 1972. Pat. No.

3,311,587 a bucket pivoted on the boom by a bucket ram. The

hydraulic circuit includes a main pump that supplies [52 0.5. CI. 214/152 fluid under Pressure from a reservoir to the boom and 51 Int. Cl. 865g 7/00 bucket rams through control vales- An auxiliary [58] Field of Search 214/140, 762, 763, 764, wit pp fluid from the reservoir to the bucket 1 214/152 ram to maintain the material handling unit at a prede- 4 termined attitude with respect to the reference plane [56] I Referen s Cit d and the auxiliary circuit includes a pump that is driven UNITED STATES PATENTS by the flow of fluid between the boom control valve 3,032,215 5/1962 French et al 214/763 and the boom ram 3,563,137 2/1971 Graber 214/763 3 Claims, 3 DrawingFigures 2 o I 36 52 40 t /8 a0 a I j 'i T o W i J 2a 3 0 3,695,474 10/1972 Blakely 214/764 Primary Examiner-Robert J. Spar Assistant ExaminerRoss Weaver Attorney, Agent, or FirmDressler, Goldsmith,

Clement & Gordon, Ltd.

' [57] ABSTRACT The disclosure relates to a hydraulic circuit for a vehicle having a boom pivoted thereon by a boom ram and 900mg: VALV PATENTEDUEC24|974- 3 f- FIG. 2

UNIT

VALVE 29/ (AUX; I06 //6 L70 (7 Z MOTOR MOTOR This is a division, of Application Ser. No. 272,365,

filed July 17, 1972 now U.S. Pat. No. 3,811,587.

FIELD OF THE INVENTION The present invention relates generally to material handling equipment and more particularly to improved method and apparatus for controlling the position of a bucket supported on a boom.

In conventional. earth moving equipment, such as bucket loaders, the equipment generally includes one or more lift arms, generally referred to as a boom, pivotally carried on a vehicle with a bucket pivoted on the free end of the lift arms. Generally, the lift arms are raised and lowered on the vehicle by a fluid ram having fluid supplied thereto through a control valve while the bucket ispivoted on the end of the lift arms through an additional fluid ram having fluid supplied thereto through a further control valve. The fluid is-generally supplied to the respective control valves from a reservoir through a pump. v

In normal operation, the bucket or material handling unit is positioned in a dig position and is forced into a pile of material by forward movement of the vehicle.

, The bucket is then pivoted or rolled back on the boom or lift arms with sufficient force to break out the mass of material within the bucket from the remainder of the pile.'Subsequently, the lift armsare elevated a sufficient distance to raise the bucket above the ground and 2 mounted material handling unit. The auxiliary circuit supplies fluid for maintaining the unit at a level condition and the amount of fluid supplied is a function of thespeed at which the boom is raised and lowered with respect to the vehicle.

The method of the present invention contemplates supplying fluid under pressure from a reservoir through a main pump to first and second control valves that are selectively actuated to respectively control the flow of fluid to and from a boom ram and a material handling unit ram. Fluid for maintaining the unit at a level condition during the raising and lowering of the boom is supplied through an auxiliary circuit that includes an auxiliary pump drivenby fluid flowingbetween the boom ram and its associated valve to deliver fluid from the reservoir to the unit ram. In the specific method disclosed herein, the pump is a reversible pump that is driven by an auxiliary motor inone of the conduits between the boom ram and its associated valve so that fluid flow in either direction in the conduit will drive the pump.

The method of the present invention is performed. with a hydraulic circuit that supplies fluid to a boom ram that is capable of raising and lowering a boom pivoted on a vehicle and a unit ram that is capable of pivoting a material handling unit on the boom. The hydraulic circuit includes a reservoir with pump means for supplying fluid'under pressure from the reservoir.

' The hydraulic circuit also includes first hydraulic cirthe vehicle is driven to some other location. Upon reaching the subsequentlocation, the bucket is pivoted to a dumping position where the contents are discharged, after which the operation is repeated.

In an operation such as this, it is important that the bucket be maintained at a level position while the lift arms are being raised and lowered to prevent the material or contents'from being spilled.

Many of the self-leveling devices take hydraulic fluid for leveling directly from the pump that also supplies fluidfor raising and lowering the boomor lift arms.

In large units of this type, some difficulties have been encountered in having sufficient fluid available from the pump to allow the boom to be raised at its desired speed and at the same time provide the necessary amount of fluid for performing the leveling function for the unit as the boom or lift arms are being raised and lowered.

Other self-leveling systems utilize slave cylinders between the lift arms and the support and fluid is directed from these cylinders to the bucket fluid rams during the raising and lowering of the lift arms to produce the leveling function. However, the slave cylinders" self-leveling requires heavy mounting points for I the cylinders since they must absorb large forces developed by the hydraulic fluid as it is being transferred between the cylinders and bucket rams.

A furthersystem includes links that are interposed between the support and the bucket and are usually carried by the lift arms to produce the leveling function. This type of system requires heavy links on top of the lift arms.

SUMMARY oF THE INVENTION The present invention incorporates an auxiliary circuit into the normal hydraulic circuit for a vehicle cuit means connecting the pump and-reservoir to the boom ram and second hydraulic circuit means connecting the pump means and reservoir to the unit ram. The hydraulic circuit further includes auxiliary hydraulic circuit means cooperating with the first hydraulic circuit means and connected to the second hydraulic circuit means for supplying fluid under pressure from the reservoir to the unit ram and maintaining a predeter- -mined attitude of the material handling unit with respect to a reference plane as the boom is raised and lowered on the vehicle. Theauxiliaryhydraulic circuit means incorporates an auxiliary pump that is driven by .fluid flow in the first hydraulic circuit means to supply fluid to the unit motor for performing the leveling operation. v

More specifically, the first hydraulic circuit means includes a boom control valve that is connected to the main pump and reservoir and to the boom ram through first and second conduits. The second hydraulic circuit means includes a unit control valve also connected to the main pump and to the reservoir as well as being connected to the unit motor through first andsecond conduits. The auxiliary hydraulic circuit means includes an auxiliary motor in one of the conduits between the boom coritrol valve and the boom ram with the auxiliary pump as a function of the flow of fluid in unit ram so that fluidunder pressure developed by the auxiliary pump is available for performing the leveling function of the material handling unit.

In one embodiment of the invention, the auxiliary pump is connected to the unit control valve which in-v corporates separate flow paths to allow fluid to be supquired for performing thelevelingfunction for the ma terial handling unit.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF I DRAWINGS FIG. 1 is a schematic illustration of a vehicle having a boom pivoted thereon with a bucket pivoted on the boom with thehydraulic circuit of the invention incorporated therein;

FIG. 2 is a'schematic illustration of thehydraulic circuit of the present invention; and,

FIG.- 3 is a slightly modified form of a hydraulic circuit.

DETAILED DESCRIPTION While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail two specific embodiments, with-the understanding that the present disclosure is to be considered asanexemplification of the principles of the invention and is not intended to limit the invention to .the embodiments illustrated.

FIG. I of thedrawings generally shows the environment for the present invention and includes tractor or vehicle having upright supports 12 on opposite sides thereof (only one being shown). Each upright has .lift

arm 14 pivotally supported at the upper end on pivot pins 16. The lift arms define whatmay be termed a boom which has material handling unit or bucket 18 pivotally supported about pivot pins20. The lift arms or boom are adapted to be raised and lowered relative to the-vehicle through boom ram 22 that consists of cylinder 24 pivoted on support 12 by pivot pin 26 withpiston rod 28 pivoted'on boom 14 by pivot pin 30. Again, two such boom rams are respectively attached between the two lift arms and the supports on opposite sides of the vehicle.

Material handling unit or bucket 18 is pivoted on the outer end of boom 14 through unit ram 32 cooperating with a parallelogram linkage that consists of links 34 and 36 pivotally interconnected at 38 and respectively pivotally connected at 40 to the material handling unit and at 42 to lift arm 14. Fluid ram 32 consists of cylinder 50, trunion mounted on link 36 with piston rod 52 pivotally connected on lift arm 14 by pivot pin 54. Two

unit rams 32 and links 34 and 36 are incorporated into the circuit and cooperate with the respectivelift arms 14.

ond conduit 68 connecting reservoir 68 to valve bank 66. The hyrdaulic circuit also includes first hydraulic circuit means 70 connecting valve bank 66 to boom The hydraulic circuit for supplying fluid to boomrams 22 and'second hydraulic circuit means 72 connecting valve bank 66 to unit rams 32.

First hydraulic circuit means includes boom valve means 74, forming part of valve bank 66, and first and second conduits 76,78 connected-to opposite ends of cylinders 24. Second hydraulic circuit means 72 includes unit valve means and first and second conduits 82,84 connected to opposite ends of cylinders 50 forming part of unit rams 32. v

With the hydraulic circuit sofar described, actuation of boom valve means 74 in either direction from the neutral position will connect conduits 64 and 68 to conduits 76 and 78 to extend and retract piston rods 28 thereby raising and lowering boom 14 with respect to vehicle 10;

Likewise, actuation of unit control valve means 80 in opposite direction from neutral position will connect conduits 64 and 68 to conduits 82 and 84 thereby extending and retracting piston rods 52 with respect to cylinders 50 to pivot material handling unit 18 with respect to the boom.

As was indicated above, during the raising of the boom relative to the vehicle, when the material handling unit is filled with material, it is necessary to constantly reposition the material handling unit while theboom is being raised to prevent the contents from being spilled. It will be appreciated that if the material handling unit is not constantly being repositioned, the attituide with respect to a reference plane will constantly be changing as the boom is raised and lowered.

The present invention provides a simple system that eliminates the need for having large and heavy pivotal connections, such asrequired inthe slave cylinders system, and also eliminates the need forlarge links on the lift arms so that the operators visibility is not effected by the present system. The system also has greater flexibility in the placement of components for the system.

. The present system to be described also maintains the advantage of other hydraulic self-leveling systems and, at the same time, insures that there is always sufficient fluid available for performing the leveling as well as the lifting functions- According to the present invention, the hydraulic circuit incorporates an auxiliary hydraulic circuit that becomes operative at any time the boom is raised and lowered to produce a separate sourceof fluid for the unit rams to perform the self-leveling function. With reference to FIG. 2, auxiliary hydraulic circuit means is incorporated into the hydraulic circuit and cooperates with first hydraulic circuit means 70 for supplying fluid from reservoir 60 to unit ram 32 and the fluid supplied thereto is capable of maintaining a predetermined attitude of the material handling unit with respect to a fixed reference plane as the boom is raised and lowered on the vehicle.

Auxiliary hydraulic circuit means 100 includes reversible auxiliary pump 102 having opposite sides or ports connected to reservoir 60 through first and second conduits 104 and 106. First and second conduits 104 and 106 each having unidirectional check valve 114 and each conduit, 110, 112 has check valve means 116 to limit the flow of fluid in one direction leading means 114. Auxiliary valve 114 is connected to first "and second conduits 82 and 84 through further conduits 120 and 122 and is also connected to reservoir 60 through conduit 124. 7 According to the primary aspect of the present invention, auxiliary pump 102 is operated as a function of the flow of fluid in first hydraulic circuit means 70. This is accomplished by auxiliary motor 130 in one of conduits 76,78 with auxiliary motor 130 connected through shaft 132 to reversible auxiliary pump 102.

With the auxiliary circuit incorporated into the main hydraulic circuit as shown and described, reversible auxiliary pump will only be operated when fluid is flowing to and from boom rams 22. It will be appreciated that this arrangement substantially increases the service life'of the auxiliary pump since the pump will only be operating at times when fluid is necessary for maintaining the unit or bucket level.

Auxiliary 'valve 114 is actuated in response to a change in angular position between material handling unit 18 and boom 14 while main unit control valve 80 is in the neutral position. The actuating means for auxiliary valve 114 may take any, number of forms and a linkage system 150 has been illustrated. By way of example, and not of limitation, the means for actuating auxiliary valve 114 may be of the type illustrated in Horsch US Pat. No. 3,534,881; Horsch US. Pat. No. 3,578,191 and Seaberg et al. US. application Ser. No.

58,588 filed July 27, 1970, all assigned to the assignee of the present invention.

. The operation of the hydraulic circuit of the present invention 'will be described in connection with the method aspect of the present invention. The pivoting of the boom on the vehicle and the material handling unit on the boom is accomplished by suppling fluid under pressure through pump 62 from reservoir 60 to first and second valves 74 and 80, which are selectively actuated to supply fluid under pressure to rams 22 and 32. The respective rams will pivot the boom on the vehicle and the material handling unit on the boom.'At any time fluid is being supplied to boom rams 22, auxiliary motor 130 will drive auxiliary pump 102 in the appropriate direction to draw fluid from reservoir 60 through either conduit 104 or 106 and supply this fluid under pressure through the other of the conduits to auxiliary valve 114. Auxiliary valve 114 is actuated when the angular position between boom.14 and mate- .rial handling unit 18 is changed so that'the fluid supplied to auxiliary valve 114 will be directed to either conduit 82,84 while the other of these conduits is connected to reservoir 60 through conduit 124.

As can be seen from the description, the auxiliary hydraulic circuit produces fluid under pressure for delivcry to unit rams 32 only when such fluid is necessary for producing the self-leveling function. At other times,

auxiliary pump 102 is in a stationary condition thereby substantially increasing the service'lifeof the unit. F urthermore, only a small pump is necessary since the hydraulic fluid needed for the self-leveling function is rather small in comparison to the amount of fluid required for supplying hydraulic rams 22 and 32.

A slightly modified form of the invention is shown in FIG. 3 and like reference numerals have been applied to the same parts. The only distinction betweenthe respective hydraulic circuits shown in FIGS. 2 and 3 is that unit control valve means 800 and auxiliary valve means 114a are incorporated into a single valve. This valve is of the commercially available type wherein unit control valve 80a has a second midsection inlet 170 for receiving fluid from auxiliary pump 102 and directing this fluid through separate flow paths leading from inlet 170 to the respective conduits 82 and 84. Since the combined main and auxiliary valve is commercially available from companies such as Commercial Shearing Co., Youngstown, Ohio, no detailed description appears to be necessary.

Summarizing briefly, the present invention provides hicle by a boom ram and a material handling unit pivoted on the boom bya unit ram comprising the steps of supplying fluid under pressure through a pump from a reservoir to first and second valves; selectively actuating. said valves to supply fluid under pressure to said rams for pivoting the boom on the vehicle and pivoting the unit on the boom; and supplying fluid under pressure from said reservoir through an auxiliary circuit bypassing said pump to the unit ram to provide fluid for maintaining a predetermined attitude of said unit relative to a reference plane while the boom is being raised and lowered.

2. A method as defined in claim 1, in which said auxiliary circuit includes .a pump and in which said pump is driven by'fluid flowing between said boom ram and the valve supplying fluid to said boom ram.

3. A method as defined-in claim 2, in which the pump in the auxiliary circuit is reversible and there are first and second conduits between the boom ram and the valve supplying fluid to the boom ram; and in which the pump in the auxiliary circuit is driven by fluid flowing in opposite directions through one of the first and second conduits.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3032215 *Aug 29, 1958May 1, 1962Deere & CoLoader bucket leveling control
US3563137 *Jun 30, 1969Feb 16, 1971Cessna Aircraft CoHydraulic self-leveling control for boom and bucket
US3695474 *Aug 5, 1970Oct 3, 1972Case Co J IHydraulic control linkage for implement
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6912804Sep 10, 2003Jul 5, 2005Volvo Construction Equipment Holding Sweden AbLoader-type heavy-construction machine
EP0391808A1 *Apr 6, 1990Oct 10, 1990Fdi- Sambron, Societe AnonymeTelescopic hoisting device for a vehicle, in particular for a loader
WO2002081828A1 *Mar 20, 2002Oct 17, 2002Charles GeorgesLoader-type heavy-construction machine
Classifications
U.S. Classification414/815
International ClassificationE02F3/42, E02F3/43
Cooperative ClassificationE02F3/433
European ClassificationE02F3/43B2H