WO2003038199A1

WO2003038199A1 - Lift arm support and storage construction for small loader

Info

Publication number: WO2003038199A1
Application number: PCT/US2002/034581
Authority: WO
Inventors: Mark F. Bares; James H. Page
Original assignee: Clark Equipment Company
Priority date: 2001-11-01
Filing date: 2002-10-29
Publication date: 2003-05-08

Abstract

A lift arm assembly (24) for a small or 'mini' track driven loader (10) is pivotally mounted onto a self propelled frame (12) for movement between a raised and a lowered position. A support strut (60) is provided that fits over an extended rod (29) of the lift arm operating cylinder (26) with the lift arm assembly (24) raised, and will prevent the lift arm assembly (24) from lowering. The support strut (60) is stored in a front tubular cross member (70) of the lift arm assembly (24). Additionally, the front cross member (70) supports an upright strut (44) that acts as a back stop for material in a bucket (48), so that if an object in the bucket (48) tends to roll rearwardly, it will be deflected or stopped. Each lift arm (24A, 24B) has a rear portion (25) extending downwardly and forwardly to join side portions (32) of the lift arms (24A, 24B) that are substantially parallel to the hydraulic actuators (26) used and parallel to the upper lengths (14U) of the respective drive tracks (14D) in a lowered position of the lift arm assembly (24).

Description

LIFT ARM SUPPORT AND STORAGE CONSTRUCTION

FOR SMALL LOADER

BACKGROUND OF THE INVENTION The present invention relates to a lift arm assembly construction for use on a small loader that is operated from the rear of the loader. The lift arm assembly can be raised for lifting loads. A mechanical support is provided for holding the lift arms in their raised position and is stored in a cross member of the lift arm assembly. The lift arm assembly has a upright strut for ^' intercepting and deflecting objects that may roll from the back of the bucket if the bucket is overfull and the lift' arm assembly is fully raised. Skid steer loaders commonly use a mechanical stop that will carry compression loads and is placed between the rod end cap of an extended cylinder and the lift arm so that the lift arm will not lower and the cylinder cannot retract. Mechanical stops are used when the loader is being serviced. Various mechanical stops that will retract under a spring load have been advanced. In small or mini loaders, space is limited, and compact lift arm geometry is such that typical retractable stop designs cannot be integrated.

SUMMARY OF THE INVENTION The present invention relates to a _. small, self propelled loader with a lift arm assembly that can be raised and lowered. Controls for the lift arms and ground drive are all at the rear of the machine, and accessible by an operator standing on the ground or standing on a support platform at the rear of the machine. The lift arm pivots are generally a little higher than waist high on an operator. The operating control levers are just to the rear of the lift arm pivots for accessibility of the operator.

The lift arms are made into a rigid lift arm assembly with a cross member at the front end of the lift arms that also supports an upright strut for mounting a cylinder or actuator that is used for tilting the bucket or work implement.

With the lift arms pivoted upwardly so the load is raised the maximum amount in the small loader, there can be a substantial roll back or tilt back of the bucket. A structural member is integrated into the strut that mounts the cylinder for tilting the bucket. The structural member acts as a backstop for intercepting and deflecting objects, such as logs or rocks that may fall from the bucket when the lift arms are raised to the top of their travel and the load is not kept level.

The cross member of the lift arm assembly opens through one side of lift arms and is utilized for- -storing a mechanical- support ^"that: -holds' -the - lirft arms in their raised position when the loader is serviced. This eliminates the need for storing the support externally of the lift arm, where it can be in the way or add to the size of the small loader. The support has a key shaped end that includes a tang that fits into a recess formed between side plates to provide a way of knowing the correct orientation for installation.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevational view of a small, compact walk behind loader made according to having lift arms constructed according to the present invention;

Figure 2 is a perspective view of the loader of Figure 1;

Figure 3 is a side view of the loader of Figure 1 showing the lift arm in raised position in dotted lines;

Figure 4 is a fragmentary enlarged view showing the upper portions of the lift arms in a raised position and a support strut in place;

Figure 5 is a sectional view taken on line 4—4 in Figure 3;

Figure 6 is a rear fragmentary exploded perspective view of the forward portions of the lift arm assembly, showing the cross tube that holds the lift arms in an assembly and a lift arm mechanical support; and

Figure- J- ts-^_ "f-r"agmen . y"^~f "o X-perspective- view of an outer end of the lift arms . DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS Referring to. Figure 1, a miniature (mini) loader indicated generally • at 10 is a walk behind power loader that has a body or frame 12. The frame 12 supports a track assembly 14 on each side of the loader for propelling the loader 10 in forward and reverse directions through the use of drive hydraulic motors indicated generally at 16. The drive motors 16 are hydraulic motors operated through a pump 19 and a valve arrangement with a separate valve 18 for each motor 16 which is part of hydraulic valve controls 20 at the upper end of a control panel for the loader. The pump 19 is driven by an internal combustion engine 45 mounted on the body or frame in a housing 17 that has a cover 17A. The engine is centered laterally on the frame.

Each track assembly includes a track frame 14A, a drive sprocket 14B and a front idler wheel 14C over which a track 14D is mounted. Bogie wheels 14E are also provided on the track frame for supporting the track.

The body or frame 12 has spaced plates forming upright supports 22 at the rear portions, and these supports 22 extend upwardly a little higher than waist level of an operator standing on the ground-.- The — upright—supports' " in- -turn- pivotally s^'upport base or rear ends of the lift arm assembly 24 on pivots 21. As shown, the pivots are at or near the uppermost part of the loader. The lift arm assembly 24 includes individual lift arms 24A and 24B, on opposite sides of the body or frame, and each lift arm has a base end portion or rear plate portion 25 that inclines downwardly at an angle essentially parallel to the rear portions of the body frame and engine cover. The base portion 25 of each lift arm has bend portion 57 forming a forward end of the base portion, which joins a side lift arm portion 32 that extends parallel to the upper length 14F of the respective track 14D of the track assembly on that side of the loader with the lift arm assembly in a lowered position. The side lift arm portions 32 join forward lift arm portions 34 that are curved to fit around the front of the drive tracks, 14D, respectively.

** Also, the radius portion 60 has a forwardly extending portion indicated generally in dotted lines at 62 that extends into a tubular interior of the tubular side arm portions 32. The rear portions can be plates of steel, or can be tubes if desired. The forward lift arm portions 34 are plates formed with contoured recesses formed with a radiused surface 34R.

The lift arm assembly 24 is raised and lowered with extendible and retractable double acting -hydraulic -- cyiinders -or- -actuators 26 opera-ting - with hydraulic pressure from the pump 19 and controlled by valves forming part .of the controls 20. The cylinders 26 (there is one on each side, and only one is shown) have base ends pivotally mounted as at 28 to the upright portions of the body or frame 12, and the cylinders have extendible and retractable rods 29 that ' have rod ends that are pivotally mounted as at 30 to each of the ^• side lift arm portions 32 of the lift arm assembly 24. The lift arms 24A and 24B include the side lift arm portions 32, and forwardly extending lift arm portions 34 that curve forwardly over the forward ends 36 of the drive tracks. Pivot pins 38 in turn are used for mounting a quick attachment plate 40 of conventional design normally used with the BOBCAT® skid steer loaders made by Bobcat Company, an unincorporated Business Unit of Ingersoll-Rand Company.

The attachment plates 40 are well known, and the pins 38 permit the attachment plate to be pivoted about a horizontal axis by a bucket control cylinder 41 that has its base end connected as at 42 to an upright strut 44 mounted on a cross member 70. Crossmember 70 also holds the lift arms 24A and 24B together to form the lift arm assembly 24. The rod end of the actuator or cylinder 41 is connected as at 45 to a bracket on the attachment plate 40. A bucket -4-8—i-s —s-hθwn—in- -position- on--the- -atta-e-hmen-t -plate- 4-θy- and this is supported on the attachment plate 40 in a known manner. When the actuators or cylinders 26 are fully extended, as shown in dotted lines in Figure' 3 the lift arms 24A and 24B are at a substantial upward angle, and as shown in Figures 3 and 4, this results in a considerable "roll back" or backward tilt of the rear wall of the bucket 48 when the bucket remains in its position for loading. The upright strut 44 that is used for the bucket cylinder 41, is provided with an upwardly projecting backstop 46, which, as can be seen in Figures 6 and 7, is formed by spaced apart

, plates to provide a lateral width for the backstop.

The cylinder 41 fits between these plates. The plates of the backstop form a forward edge 50, that is above the rear lip or corner of the attachment plate 40 and above the back wall 51 of the bucket 48.

If the bucket 48 is heaped with objects or chunks of materials, generally as indicated by 52, the excess objects ^• may tend to roll out, backwardly. If this happens the edge 50 of the two spaced plates that form the strut 46 will tend to stop or deflect the objects tending to roll back along the lift arms 24.

When the lift arm assembly 24 is in this raised position, and the engine 45 or other components that are mounted on the body or frame in compartment 17 and above the tracks are to be serviced,- -a ■mec-hani-c-al- i-ift -a-Hti -s-upport s-t-r-u-t 60 -is placed between the outer end of one of the cylinders 26 and the lower side of the corresponding lift arm adjacent the outer end of the extendible and ^'retractable rod 29 on that cylinder to the mechanical strut support will insure that the cylinder 26 cannot retract, causing the lift arm assembly 24 to lower.

Mechanical support struts are used on many loaders, and in the compact loader of the present invention, the ability to store such a support strut conveniently and unobtrusively is of importance. The storage arrangement is illustrated in Figure 4, 5, 6 and 7. The support strut 60 is a channel shaped member that is of size to fit over the cylinder rod 29, and includes a base end 62 that has guides fingers 64 that will position and retain the support strut on the end of the cylinder 26. The base end 62 rests against the end surface 26A of the cylinder 26. The mechanical lift arm support strut 60 has a flange 65 at the opposite end of the support strut. The flange 65 has a recess aligned with the longitudinal channel opening of the lift arm support strut 60, so it fits over the rod 29 like a saddle. The flange 65 engages the lift arm assembly to provide a support or stop for the lift arm assembly adjacent to the connecting pin or pivot 30 for the rod end on the rod 29 of the cylinder 26. The flange 65 rests against a curved edge 67 of the forward lift arm portion 34 and an edge 68 of a side skirt of f-lange 69 that i-s welded- i-n- -the -1-i-f-t -arm- -assembly nd is spaced from the front arm portion 34 sufficient to permit the rod end of cylinder rod 23 to fit in the space . The rectangular tubular cross member 70 forms a structural member and is reinforced to the front lift arm portions 34 with braces or gusset plates 72. The cross member 70 extends across the lift arm assembly. Figure 4 and 6 show the right end of the cross member 70. As stated, cross member 70 also provides the main support for the upright strut 44 and the back stop member 46 on the upright strut.

The lift arm support strut 60 is stored inside the rectangular cross section tubular cross member 70, and extends across the lift arm assembly when stored. The lift arm support strut 60 is retained in place in the cross member with a U-shaped bracket 74 on the side of the associated lift arm, which receives a tab or key 76 on the end flange 64 of the strut 60 between side walls of the bracket 74. The flange 65 stays on the outer end of the lift arm and cross member 70, and will not slide into the interior of the cross member: A lock pin 78 is passed through openings in the side walls of the U- shaped bracket 74, and is positioned on the outside of the tab 76 to hold the lift arm support strut 60 in the cross tube 70 during use of the loader.

The lift arm support strut .60 is used to mechanically support the lift arm assembly. The -1-ojag-i-tudi-nal channel--- opening of -the strut -60 f-its over the rod 29 and abuts against the cylinder end surface 26A. The flange member 65 is placed up near the rod end of the cylinder rod 29. The lift arm support strut rests over the rod 29 and the tab 76 extends upwardly and aligns with the space or recess formed between front lift arm portion 34 and the skirt 69. The tab 76 orients the lift arm support strut so it will not be likely to rotate out of position and fall off.

The cylinder ^' 26 can then be retracted slightly until the edges 67 and 68 engage flange 65 and the tab 76 slides between the forward lift arm portion 24 and the skirt 69. With the guide fingers 64 in position, the lift arm support strut is locked in position, and will not fall out. The lift arms cannot lower until the support strut 60 is removed by reversing the installation sequence. The lift arm assembly 24 is made to provide a unique support for the tilt cylinder for the bucket, and incorporates in that support a deflector strut that is positioned above the upper edges of the bucket and positioned to deflect objects that may fall out of the bucket when the lift arms are raised fully and the bucket is not kept level.

As can be seen in Figures 1 and 2, the side rm portions 32 are substantially parallel to and spaced upwardly from an upper length or reach 14U of the track 14D that forms part of the track assembly 14;--The -base portions --2-5 - of the lift- -arms -extend so that the side arm portions 32 are parallel to the longitudinal axis of the hydraulic actuators or cylinders 26. This geometry forms a compact assembly. The cylinder rod is attached to the plates 34 forming the forward lift arm portions so when the lift arms are lowered the cylinders 26 are in the position shown in Figure 1. There is a substantial mechanical advantage even in this lowered position between the pivot point 21 and the pivot 28 of the base of the cylinders 26 where they join the frame.

_.As the lift arms are raised, as shown in the various dotted line positions in Figure 3, the cylinders 26 and the side arm portions remain fairly close to parallel, so that the lifting mechanical advantage remains substantially uniform relative to the pivots 21. Dotted line lift arm positions are shown at 80, 82 and 84. Position 84 is a fully raised position of the lift arms, and it can be seen that the cylinders 26 and the center portions 32 of the lift arms stay relatively close to parallel.

It should also be noted that the frame 12 can have counterweights 86 mounted thereon at the rear, the size and number are selected to be suitable for the type of operation that is being carried out with the loader.

In operation, the operator will stand or walk behind the loader, and operate the controls with the control handles 20 to move the loader through motors 16- -a-nd to -raise and iowe-r the -f-fe- -a-rm- assembly 24 as desired. The side-to-side visibility is greatly enhanced by having the offset section at the base end of the lift arm to drop the side portions 32 down along the sides of the housing for the engine and substantially parallel to the top reach or lengths of the tracks. Additionally, the moving of the side portions ^■ of the lift arm aids in lowering the center of gravity of the machine, particularly in the lower portions of the lift path. The lower center of gravity aids stability. The small loader that is disclosed has no operator's platform.

The propulsion system for moving the loader .is disclosed specifically as a track unit. However, skid steer loaders are commonly mounted on wheels on the sides that are driven simultaneously on each side, from a separate motor on each side. The present loader can be wheel mounted, with the tops of the wheels on a plane parallel to the center portion of the lift arm and close to the top plane just like the top length of the track is positioned. Thus the propulsion system that supports the loader for movement can be sets of wheels mounted in place of the tracks shown.

The controls for operating the lift arms can be conventional valve controls. The propulsion drive motors 16 (there is a motor on each side of the frame) will propel the loader across the ground. There is a separate drive motor 16 for each of the •trac-ks -shown-,- -and- -the d-r-ive motors -are i-nd-i-vi-duaH-y controlled so that the load can be steered as well as being movable in forward direction or reverse direction. Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and' detail without departing from the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A loader apparatus having a frame, a lift arm assembly pivotally mounted on the frame and movable between a raised and a lowered position, the lift arm assembly comprising spaced apart lift arms, and a cross member holding the lift arms together to form the assembly, a hydraulic cylinder having an extendible or retractable rod connected between the frame and the lift arm assembly, a mechanical support for supporting compression loads mountable on the rod of the cylinder when extended to support the lift arm assembly, the mechanical support being positioned between an end of the cylinder and the lift arm assembly to prevent the lift arm assembly from lowering when the mechanical support is in place, the cross member being tubular and having an interior opening open on at least one side of the lift arm assembly, said cross member being of size to receive the mechanical support to store the support.

2. The apparatus of claim 1, and a releasable latch for holding the mechanical support in position within the opening of the- cross member.

3. The apparatus of claim 1, wherein said mechanical support has a base end for engaging an end of the cylinder, the base end having finger

^"projections —for ^" fitting- -over -a "side- of -the cylinder when the base end is resting on the end of the cylinder.

4. The apparatus of claim 3, wherein the mechanical support has a flange for engaging a portion of he lift arm assembly which includes spaced walls defining a recess and the flange having a tab extending outwardly and fitting into the recess when the support is in a working position between the end of the cylinder and the portion of the lift arm, and the tab engaging a retainer bracket when stored in, the cross member.

5. The apparatus of any one of claims J, 3 or 4, wherein said mechanical support is channel shaped in cross section.

6. A lift arm assembly for a loader including a pair of lift arms, a tubular cross member at forward ends of the lift arms, and a compression carrying support strut for supporting the lift arm assembly relative to an end of a lift cylinder, the support strut being slidably removably mounted in said tubular cross member, and a retainer to hold the support strut in the tubular cross member during use of the lift arm assembly.

7. The lift arm assembly of claim 6, and an upright on said cross member substantially centered on the lift arm assembly, said upright extending sufficiently upwardly to project above a rear portion

-of^~a—work tool held at--the- outer- -end of the lift arm assembly when the lift arm assembly is in a raised position.

8. The lift arm assembly of claim 7, wherein said lift arm assembly has a hydraulic tilt cylinder for controlling movement of the work tool about a horizontal axis, said hydraulic tilt cylinder having a base end mounted on said upright.

^•9. A loader lift arm assembly comprising a lift arm for pivotal mounting to a prime mover, a lateral support member at an outer end of the lift arm, a load carrier mounted to the outer end of the lift arms, an upright strut on said lateral support member, a hydraulic cylinder . extending between the upright strut and the load carrier for controlling tilting of the load carrier about a horizontal axis, and the lift arm being movable its pivot to raise the outer end wherein the lift arm extends upwardly at an angle, and a deflector extension on the upright strut that extends above the mounting of the hydraulic cylinder to provide for deflecting objects rolling

"over a top of the load carrier when the lift arm is

.in a raised position.

10. The lift arm of claim 9, wherein the load carrier is a bucket pivotally mounted to the outer end of the lift arm.

11. - The lift arm of claim 10, wherein lift arm is a lift arm assembly of first and second spaced arms - the lateral -support" -member ^•-compr±-s±ng -a cross member extending between the first and second spaced arms .

12. The lift arm of claim 11, wherein said cross member is tubular, and has an open end opening through one of the spaced arms and accessible from an outer side of the one lift arm.

13. A loader and lift arm assembly having a frame, operator controls at the rear of the frame, accessible to a standing operator, a propulsion system for moving the frame along a surface, including drive members on opposite sides of the frame, an engine on the frame mounted between the drive members, the frame having upright members at the rear portions thereof, a lift arm for lifting loads including a base portion pivotally mounted to the upright member of the frame, a center side portion, and a forwardly extending portion extending forwardly of the frame and adapted for supporting a work tool, an actuator for pivoting the lift arm about the pivot, the lift arm rear portion inclining downwardly and forwardly from the pivot and joining the center side portion of .the lift arm, the center side portion being above the drive members in a lowered position of the lift arm and positioned alongside the engine compartment, and the lift arm center side portion joining the forwardly extending portion.

—14.-- -^•• --—The.- -loader- and--l-i-ft -.-a-rm-- o-f —-claim- -1-3, wherein the lift arm has a forwardly extending portion inclining downwardly from the center side portion for attachment to a work tool. -IS

15. The loader of claim 14, wherein said lift cylinder is connected to the frame and extends forwardly to a forward end of the lift arm, said lift cylinder and the center side portion of the lift arm being substantially parallel when the lift arm is in a lowered position.