Abstract:
A mounting for a tooth bar to a mounting surface of a thumb sub-assembly, the mounting including one or more inwardly narrowing slots located adjacent the mounting surface and into which a part of a mounting portion of the tooth bar can be wedgingly engaged, there being fixing means for fixing the tooth bar into engagement with the mounting surface following the mounting portion being wedgingly engaged.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to material handling equipment such as excavators, backhoes, and clamping and grappling equipment, and the like. More particularly it relates to a mounting for a tooth bar on a thumb assembly for use with such equipment. 
       BACKGROUND 
       [0002]    The use of a thumb, with attached tooth bar, on excavator machinery is well known. Typically the thumb is used in conjunction with the excavator bucket so as to make the bucket more effective in picking up material. For example in demolition sites a thumb is a particularly useful means of grabbing material which would otherwise be difficult to be picked up solely by a bucket. 
         [0003]    The thumb is typically pivotally mounted to the excavator arm and is controllable, by an hydraulic ram. The thumb has a tooth bar attached to its distal outer end, this tooth bar generally being configured to suit the particular type of bucket with which it is to be used. For example, the tooth bar may have four or six teeth depending on the number of teeth mounted to the edge of the bucket. 
         [0004]    Because of the differing end user requirements it is often the case that the manufacturer of the thumb will manufacturer thumb assemblies particularly suited for the end application. 
         [0005]    Consequently there is always a lead time between an end user ordering a thumb and it actually being delivered from the manufacturer. 
         [0006]    Accordingly there is a need for a more modular system whereby the manufacturer can have a standard thumb sub-assembly and attach to this a suitable pre-manufactured tooth bar depending on the end users requirements. 
         [0007]    Typically the tooth bar may be welded to the thumb, but with a more modular system it is more practical to have bolt on tooth bars. Bolt on tooth bars are already known, however those that are known generally suffer from draw backs - the main one being that they tend to work loose as a consequence of the forces, and sometimes extreme treatment, which the thumb experiences during normal use. 
         [0008]    It is consequently an object of the present invention to provide a mounting for a tooth bar on a thumb which at least goes some way to overcoming the problem of loosening of the tooth bar during operation of the thumb, alternatively it is an object to at least provide the public with a useful choice. 
       SUMMARY OF THE INVENTION 
       [0009]    Broadly according to one aspect of the invention there is provided a mounting for a tooth bar to a mounting surface of a thumb sub-assembly, the mounting including one or more inwardly narrowing slots located adjacent the mounting surface and into which a part of the mounting portion of the tooth bar can be wedgingly engaged, there being means for fixing the tooth bar into engagement with the mounting surface following the mounting portion being wedgingly engaged. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    In the following more detailed description of a preferred embodiment of the invention reference will be made to the accompanying drawings in which: 
           [0011]      FIG. 1  illustrates an exploded perspective view of the components of a thumb sub-assembly and associated tooth bar which is mountable to the sub-assembly by the mounting according to the present invention, 
           [0012]      FIG. 2  illustrates a perspective view of the thumb showing the tooth bar mounted to the thumb subassembly, 
           [0013]      FIG. 3  illustrates a side elevation view of the thumb when mounted to an excavator arm, and 
           [0014]      FIG. 4  illustrates a perspective view of the arrangement shown in  FIG. 3  but with the thumb inter-engaging with the bucket as shown in dotted detail in  FIG. 3 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    In the drawings  FIGS. 1 and 2  show a tooth bar of a “universal” type. By way of further illustration, however,  FIGS. 3 and 4  show a tooth bar having four teeth configured to inter-engage with the five teeth on the cutting edge of the excavator bucket. Other configurations of tooth bar can be mounted to the thumb assembly using the mounting of the present invention. 
         [0016]      FIG. 1  shows the component parts of the thumb. This includes a thumb subassembly  10  and tooth bar  11 . The subassembly  10  has a mounting plate  12  which forms a mounting surface  12 a against which a plate  13  of the tooth bar  11  can engage and be bolted thereto by a series of bolts and associated nuts  14 . 
         [0017]    The subassembly  10  includes a pair of side plates  15  which, in accordance with conventional construction, include along one edge thereof serrations or teeth  15 . At the ends of the side plates  15  opposite to mounting plate  12  are a pair of aligned openings  17 . Bushes  18  are provided for the openings  17 . Through the bushes  18  is engaged a pin  19  by which, together with selected spacers  20 , the subassembly  10  can be typically attached to the excavator arm E. To one end of the pin  19  is attached a radial extending plate  21  to which a retainer bar  22  is fitted. 
         [0018]    Between the side plates  15  is a mounting plate  23  which, as more clearly shown in  FIGS. 1 and 4 , carries flanges  24  having openings therein which align with openings in the side plates  15  and through which a thumb pin  25  can be engaged. This provides a mounting for the bush  26  of the piston rod of hydraulic ram  27 . The body of the hydraulic ram  27  has a bush  28  which is engaged in bracket  29  via pin  30 . 
         [0019]    Attached to the mounting plate  13  of the tooth bar  11  is the teeth assembly  31 . This can include a plurality of teeth  32  (see  FIG. 4 ) or in the more universal fitting of  FIGS. 1 and 2  a toothed or serrated plate  33 . 
         [0020]    The upper edge of the mounting plate  13  is preferably beveled as indicated by numeral  34 . The mounting plate  13  further includes a series, of openings which align with elongate openings  35  in the mounting plate  12  of the subassembly  10 . The bolts  14  pass through these aligned openings and with the associated nuts bolt the mounting plates  12  and  13  together. 
         [0021]    The mounting according to the present invention includes a plurality of flanges  36  which, in the illustrated form, are a pair of parallel spaced apart flanges mounted to the mounting plate  23 . These flanges  36  are, in the illustrated form of the construction, located either side of an opening  37  formed in the mounting plate  23 . 
         [0022]    Each of the mounting flanges  36  have a finger portion  37  which extends over the mounting surface of the mounting plate  12 . These fingers  37  include an edge surface  38  which faces towards the mounting surface  12   a  and is configured such that the distance between the edge  38  and the mounting surface  12   a  decreases inwardly from the distal ends of finger  37 . The result is a narrowing slot into which the beveled edge  34  can be engaged when the mounting plate  13  is bought into engagement with mounting plate  12 . There is thus a wedging action between the edge  38 /mounting surface  12   a  and the mounting plate  13  of the tooth bar  11 . 
         [0023]    Accordingly when the tooth bar  11  is mounted to the subassembly  10  the edge  34  is introduced between the edge surfaces  38  of the fingers  37  and the mounting surface  12   a . The tooth bar  11  is then driven into hard engagement with the fingers  37  so that the edge  34  is firmly wedged into position. This is shown in more detail in the enlarged part view in  FIG. 3 . The bolts  14  are then introduced through the aligned openings  35  and the openings in the mounting plate  13  and the tooth bar thereby bolted onto the subassembly  10 . The elongate nature of the openings  35  ensure that the mounting plates  12  and  13  can be bolted together irrespective of the final position of the edge  34  between the fingers  37  and mounting plate  12 . 
         [0024]    If, during use, the tooth bar  11  loosens it is simply a matter of loosening off the nuts/bolts  14  followed by a driving force applied to the tooth bar  11  so as to force the edge  34  further into wedging engagement between the mounting surface  12   a  and the edge surfaces  38  and retightening the nuts on the bolts. 
         [0025]    The present invention thus provides a mounting arrangement for a tooth bar such that the tooth bar  11  can be readily fitted onto the subassembly  10  and held firmly in place. The invention therefore lessens the likelihood of the tooth bar  11  working loose. Even though the forces to which the tooth bar will be subjected during normal use may still cause the tooth bar to loosen, the likelihood is less than with conventional mounting arrangements. If loosening does occur it is a matter of retightening in a simple and straightforward manner. 
         [0026]    It will be appreciated by those skilled in the art that the present disclosure applies to an hydraulically controllable thumb. The invention is also applicable to a fixed/rigid thumb (i.e. one which is not hydraulically operable) where the clamping action with the fixed/rigid thumb is achieved by the crowd action of the bucket.