Patent Publication Number: US-6698114-B2

Title: Lift arm support and storage construction for small loader

Description:
This application refers to and claims priority from Provisional Application Serial No. 60/335,311 filed Nov. 1, 2001, the content of which is incorporated by reference. 
    
    
     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 lift 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 
     FIG. 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; 
     FIG. 2 is a side view of the loader of FIG. 1 showing the lift arm in raised position in dotted lines; 
     FIG. 3 is a fragmentary enlarged view showing the upper portions of the lift arms in a raised position and a support strut in place; 
     FIG. 4 is a sectional view taken on line  4 — 4  in FIG. 3; 
     FIG. 5 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 
     FIG. 6 is a fragmentary front perspective view of an outer end of the lift arms. 
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
     Referring to FIG. 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 are hydraulic motors operated through a pump  19  and a valve arrangement with a valve  18  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  17 A. 
     Each track assembly includes a track frame  14 A, a drive sprocket  14 B and a front idler wheel  14 C over which a track  14 D is mounted. Bogie wheels  14 E are also provided on the track frame for support. 
     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 support base or rear ends of the lift arm assembly  24  on pivots  21 . 
     The lift arm assembly  24  includes individual lift arms  24 A and  24 B, on opposite sides of the body or frame, and each lift arm has a base end 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 joins a side lift arm portion  32  that extends parallel to the upper length  14 F of the respective track  14 D 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 fit around the front of the drive tracks,  14 D, respectively. 
     The lift arm assembly  24  is raised and lowered with extendible and retractable double acting hydraulic cylinders or actuators  26  operating 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  24 A and  24 B 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 Clark Equipment 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 . Member  70  holds the lift arms  24 A and  24 B 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  48  is shown in position on the attachment plate  40 , 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 FIG. 2 the lift arms  24 A and  24 B are at a substantial upward angle, and as shown in FIGS. 2 and 3, 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 FIGS. 5 and 6, 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 mechanical lift arm support strut  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 prime importance. The storage arrangement is illustrated in FIGS. 3,  4 ,  5  and  6 . 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  26 A 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 an edge  67  of the forward lift arm portion  34  and an edge  68  of a side skirt of flange  69  that is welded in the lift arm assembly and is spaced from the front portion  34  sufficient to permit the rod end of cylinder rod  29  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  72 . The cross member  70  extends across the lift arm assembly. FIGS. 3 and 5 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 longitudinal channel opening of the strut  60  fits over the rod  29  and abuts against the cylinder end surface  26 A. 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. 
     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 tracks shown, and the drive motors are individually controlled so that the load can be steered as well as being movable in forward direction or reverse direction. 
     It should be noted that counter weights  86  can be mounted at the rear of the loader, if needed. 
     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.