Abstract:
The present invention generally provides a wheel replacing traction assembly which uses, for propulsion, a longitudinally extending endless track disposed around and cooperating with a sprocket wheel, idler and road wheels, and a guide rail.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    There are no cross-related applications. 
       FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to traction assemblies typically used as wheel replacements for wheeled vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    Tractions assemblies for use as wheel replacement on wheeled vehicles are known in the art. Indeed, several configurations of traction assemblies have been proposed throughout the years in order to generally improve different aspects and characteristics such as the riding behaviour. 
         [0004]    Nevertheless, prior art traction assemblies still suffer from several drawbacks. Consequently, there is still room for further improvements. 
       SUMMARY OF THE INVENTION 
       [0005]    The principles of the present invention are generally embodied in a traction assembly which uses, for propulsion, a longitudinally extending endless track disposed around and cooperating with a sprocket wheel, idler and road wheels, and a guide rail. The guide rail, to which are mounted the idler and road wheels, is coupled to the sprocket wheel via a frame. 
         [0006]    The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The above and other objects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which: 
           [0008]      FIG. 1  is a perspective side view of a traction assembly embodying the principles of the invention. 
           [0009]      FIG. 2  is an exploded view of the traction assembly of  FIG. 1 . 
           [0010]      FIG. 3  is an exploded view of the sprocket wheel and frame of the traction assembly of  FIG. 1 . 
           [0011]      FIG. 4  is an exploded view of the guide rail of traction assembly of  FIG. 1 . 
           [0012]      FIG. 5  is an exploded view of the track tensioning assembly of traction assembly of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0013]    A novel traction system will be described hereinafter. Although the invention is described in terms of specific illustrative embodiments, it is to be understood that the embodiments described herein are by way of example only and that the scope of the invention is not intended to be limited thereby. 
         [0014]    Referring first to  FIG. 1 , a traction assembly  10  embodying the principles of the invention is shown. The traction assembly  10  comprises a sprocket wheel  200  adapted to be mounted to a shaft of a wheeled vehicle (not shown), a frame  300  coupled to the sprocket wheel  200 , a guide rail  400  secured to the frame  300 , idler wheels  600  and  700  respectively mounted that the fore and at the aft of the guide rail  400 , and road wheels  500  mounted along the length of the guide rail, typically on each side thereof. 
         [0015]    The traction assembly  10  also comprises an endless track  100 , typically but not necessarily made of elastomeric material. The endless track  100  has an inner surface configured to cooperate, via a plurality of typically longitudinally aligned drive lugs and guide lugs (not shown for clarity), with the sprocket wheel  200 , the idler wheels  600  and  700 , the road wheels  500  and the guide rail  400 . The endless track  100  also has an outer surface comprising a plurality of traction lugs (not shown for clarity) configured to engage the ground onto which the traction assembly  10  is operated. 
         [0016]    Referring now to  FIGS. 1 ,  2  and particularly  FIG. 3 , the configurations of the sprocket wheel  200  and the frame  300  are illustrated in more details. 
         [0017]    The sprocket wheel  200  is typically circular in shape and preferably, but not exclusively, made from light yet resistant material such as ultra high molecular weight polyethylene (“UHMW-PE”). Still, other material could be used; the present invention is not so limited. 
         [0018]    The sprocket wheel  200  defines a first side  202  and a second side  204 . The sprocket wheel  200  also defines an outer track engaging circumferential surface  201 . Respectively laterally extending from the first surface  202  and the second surface  204  are equally spaced sprocket teeth  203  and  205 . The sprocket teeth  203  and  205  are configured to conventionally engage the drive lugs (not shown) disposed on the inner surface of the endless track  100 . 
         [0019]    The skilled addressee will note that the sprocket teeth  203  and  205  respectively have surfaces  207  and  209  which are preferably coextensive with the outer engaging circumferential surface  201 . These additional surfaces  207  and  209  provide for a better engagement between the sprocket wheel  200  and the inner surface of the endless track  100 . 
         [0020]    The sprocket wheel  200  also comprises a central bore  211  configured to receive ball bearings  220  and  222  and the axle  310  of the frame  300  which will be described in more details below. The central bore  211  is preferably configured such that the ball bearing  220  and  222  can be mounted directly therein, eliminating thereby the need for a costly and heavy ball bearing cage. 
         [0021]    Disposed around the central bore  211  are four smaller bores  213  configured to receive the fasteners used to secure the sprocket wheel  200  to the shaft or wheel hub of the vehicle. Understandably, the number of bores  213  can vary according to the configuration of the shaft (not shown) onto which the sprocket wheel  200  will be mounted; the present invention is thus not limited to four bores  213 . 
         [0022]    Still referring to  FIG. 3 , the frame  300  typically comprises a lower portion  301  adapted to be secured to the guide rail  400  (described in more details below) via appropriate mounting brackets  302 , and an upper portion  303  from which extends the axle  310 . Though the frame  300  is more or less A-shaped, it is to be understood that other shapes could be used. 
         [0023]    In the preferred embodiment, and as best depicted in  FIGS. 2 and 3 , the upper portion  303  of the frame  300  is laterally offset with respect to the lower portion  301 . Though not necessary, the offset is preferred in order to provide space for the sprocket wheel  200  and to allow the sprocket wheel  200  to be located approximately above the guide rail  400  during use. 
         [0024]    The axle  310  of the frame  300  is typically fixedly mounted thereto though it could possibly be integrally formed therewith. The axle  310  preferably extends in the space provided by the offset between the upper portion  303  and the lower portion  301 . The axle  310  typically comprises three portions  312 ,  314  and  316  having decreasing diameters. The diameters of portions  312  and  316  respectively correspond to the inner diameters of the ball bearings  222  and  220 . This particular configuration prevents the sprocket wheel  200 , and the ball bearings, to be installed the wrong way. Understandably, the axle  310  could also be simply cylindrical; the present invention is not so limited. 
         [0025]    The end face  317  of the axle  310  is also preferably provided with one or more openings (not shown) for receiving one or more fasteners  226  (e.g. screws, bolts, etc.) used to fasten the cap  224  which secures the sprocket wheel  200 , and the ball bearings  220  and  222 , to the axle  310 . 
         [0026]    The skilled addressee will note that by having the ball bearings  220  and  222  directly mounted into the central bore  211  of the sprocket wheel and by mounting the sprocket wheel  200  directly to the axle  310 , the present assembly  10  eliminates the need for a costly and heavy rolling bearing cage typically found on prior art traction assemblies. The present configuration is therefore less complex and less expensive to manufacture. 
         [0027]    Referring now to  FIGS. 1 ,  2 ,  4  and  5 , the configuration of the guide rail  400  is illustrated in more details. 
         [0028]    The guide rail  400  typically comprises a main structure  420 , a sliding band  440  mounted to the underside of the main structure  420 , a plurality of wheel supporting elements  460  mounted on each side of the main structure  420 , and a track tensioning assembly  470  mounted preferably at the fore of the main structure  420 . 
         [0029]    Referring now to  FIGS. 2 and 4 , the main structure  420  is preferably an elongated aluminum extrusion having a generally arcuate shape. It is to be understood that the main structure  420  could be made by another forming process and could be made using other material (e.g. metal, metallic alloy, plastic, composite, etc.); the present invention is not so limited. In addition, though the shape of the main structure  420  depicted in  FIG. 4  is more or less angular, the main structure  420  could alternatively be shaped as a continuous curve. Furthermore, the main structure  420  is preferably hollow in order to reduce the weight thereof. 
         [0030]    The lower portion  422  of the main structure  420  is typically configured to receive the sliding band  440  which will be described below. In the present exemplary embodiment, the lower portion  422  is substantially shaped as an inverted “T” and preferably extends along at least a predetermined length of the main structure  420 . As the skilled addressee would understand, the inverted T-shaped portion is configured to engage a complementary channel  441  provided or formed in the sliding band  440 . 
         [0031]    The sides  423  and  424  of the main structure  420  are respectively provided with mounting ribs  425  and  426  and mounting holes  427  and  428 . The mounting ribs  425  and  426  are configured to receive and support the wheel mounting elements  460 . Understandably, the mounting holes  427  and  428  are configured to receive the fasteners (e.g. screws, bolts, etc.) used to secure the wheel mounting elements  460  to the main structure  420  (see  FIG. 1 ). 
         [0032]    The sliding band  440  is typically made from a material having a low coefficient of friction such as to reduce the friction between the sliding band  440  and the inner surface of the endless track  100 . As mentioned above and as depicted in  FIG. 4 , the sliding band  440  is provided with an inverted T-shaped channel  441  adapted to receive the inverted T-shaped portion of the main structure  420 . Hence, as the skilled addressee would understand, the sliding band  440  can be slid onto the lower portion  422  of the main structure  420 . Still, it is to be understood that other complementary shape as well as other mounting arrangements could be used instead. 
         [0033]    The wheel mounting elements  460  of the guide rail  400  are configured to pivotally support the road wheels  500  and the idlers wheels  600  and  700 . Each mounting element  460  comprises a wheel receiving portion  461 , adapted to receive a wheel, and a mounting portion  462  adapted to engage the main structure  420 . As best shown in  FIG. 4 , the mounting portion  462  is preferably provided with a notch  463  configured to mate with the rib  425  or  427 . The wheel mounting element  460  can thus rest on the rib  425  or  426  when mounted to the main structure  420 . 
         [0034]    Referring now to  FIGS. 2 and 5 , the track tensioning assembly  470  is illustrated in more details. 
         [0035]    The track tensioning assembly  470  typically comprises a pair of sliding brackets  471  and  472  typically configured to be mounted together at the fore of the main structure  420  and adapted to support idler wheels  600  via wheel support elements  460  (see  FIG. 1 ). The sliding brackets  471  and  472  are adapted to be secured to the main structure  420  via a push-bolt supporting bracket  490  itself adapted to be fixedly mounted to the main structure  420  (see  FIG. 1 ) via fasteners (e.g. screws, bolts, etc.). 
         [0036]    The sliding brackets  471  and  472  respectively comprise sliding portions  473  and  474  and wheel supporting portions  477  and  478 . The sliding portions  473  and  474  are respectively provided with elongated openings  475  and  476  for allowing sliding displacement of the brackets  471  and  472 . Understandably, the length of the openings  475  and  476  generally define the amplitude of the sliding movement of the sliding brackets  471  and  472 . 
         [0037]    The wheel supporting portions  477  and  478  are respectively provided with openings  479  and  480 , similar to openings  427  and  428  of the main structure  420 , for receiving the fasteners (e.g. screws, bolts, etc.) used to secure the wheel supporting elements  460  to the sliding brackets  471  and  472 . 
         [0038]    In order to improve the structural integrity of the track tensioning assembly  470 , spacers  485  could be provided between the wheel support portions  477  and  478  of the sliding brackets  471  and  472 . 
         [0039]    For its part, the push-bolt support bracket  490  comprises a mounting portion  491  and a push-bolt supporting portion  493  depending thereon. The mounting portion  491  is provided with openings  492  for receiving the fasteners (e.g. screws, bolts, etc.) used to secure the push-bolt supporting bracket  490  to the main structure  420 . 
         [0040]    As best shown in  FIG. 1 , when the push-bolt support bracket  490  is mounted to the main structure  420 , one of the fasteners used to secure the push-bolt support bracket  490  also extends through the openings  475  and  476  of the sliding brackets  471  and  472 . 
         [0041]    Returning to  FIG. 5 , the push-bolt supporting portion  493  is provided with a central passage for allowing the bolt  498  to extend therethrough. The push-bolt supporting portion  493  is also provided with a nut receiving notch or cavity for receiving a nut  499  used for maintaining the position of the bolt  498 . 
         [0042]    As partially shown in  FIG. 1 , the track tensioning assembly  470  is configured such that the bolt  498  will abut on the sliding brackets  471  and  472 . To adjust the tension in the endless track  100 , the bolt  498  needs only to be threaded, depending on the tension needed, to further push the sliding brackets  471  and  472  to increase the tension or to allow them the slide back to reduce the tension. 
         [0043]    As the skilled addressee will understand, due to the modularity of the above-described traction assembly  10 , each component of the traction assembly  10  can be more easily manufactured and the traction assembly  10  itself can be more easily assembled and requires less soldering. In that sense, the traction assembly  10  is generally less expensive than prior art traction assemblies. 
         [0044]    While illustrative and presently preferred embodiments of the invention have been described in detail hereinabove, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.