Abstract:
A track extension in combination with a track system comprises a track system having a track frame, wheels mounted to the frame and adapted to allow cyclic movement of a track about the frame, drive means in the frame adapted to transmit a drive of a vehicle to the track to drive the track in a cyclic movement. An extension frame is releasably secured to an end of the track frame. An idler wheelset is mounted to an end of the extension frame. A track is mounted about the track frame and the extension frame such that a footprint of the track is delimited at an end by the engagement of the track with the idler wheelset. A method is provided to increase a footprint of a track system.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to vehicles using tracks as interface with the ground, and more particularly to the adaptability of tracks to various terrains. 
         [0003]    2. Background Art 
         [0004]    Tracks are commonly used as the interface of a vehicle with the ground. More specifically, tracks provide more support on the ground and more traction than wheels, thus they are often used in harsh terrain conditions. As an example, army tanks, all-terrain vehicles and the like are equipped with tracks. Track conversion units are provided as replacements for wheels when a vehicle must be used in harsh conditions, such as mud, snow, etc. When a wheel-mount track conversion unit is used, the wheels on the vehicle are removed and replaced by track conversion units, such that tracks become the interface between the vehicle and the terrain. The vehicles using such track conversion units are all-terrain vehicles (hereinafter ATVs), trucks, etc. 
         [0005]    It is often desired to increase the footprint of a track on the ground. Amongst the advantages resulting from an increased footprint are the increased traction of the track, as well as the spreading of the weight of the vehicle. Such advantages cause an increased performance of the vehicle in semi-solid terrain (e.g., mud, snow, etc.). 
       SUMMARY OF INVENTION 
       [0006]    It is therefore an aim of the present invention to provide a novel track extension for track systems and track conversion units that addresses issues associated with the prior art. 
         [0007]    It is a further aim of the present invention to provide a novel method for increasing a footprint of a track system. 
         [0008]    Therefore, in accordance with the present invention, there is provided a track extension in combination with a track system, comprising: a track system having a track frame, wheels mounted to the frame and adapted to allow cyclic movement of a track about the frame, drive means in the frame adapted to transmit a drive of a vehicle to the track to drive the track in a cyclic movement; an extension frame releasably secured to an end of the track frame; an idler wheelset mounted to an end of the extension frame; and a track mounted about the track frame and the extension frame such that a footprint of the track is delimited at an end by the engagement of the track with the idler wheelset. 
         [0009]    Further in accordance with the present invention, there is provided a method for extending a footprint of a track system, comprising the steps of: i) removing a first track from a track system; ii) installing a frame supporting an idler wheelset at an end of the track system to extend a distance between the idler wheelsets and an opposed idler wheelset on opposed ends of the track system; and iii) installing a second track with a footprint of the track system being delimited by the idler wheelsets with the track moveable in a cyclic motion about the idler wheelsets; whereby a footprint of the track system is increased. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof and in which: 
           [0011]      FIG. 1  is a left-side elevation view of a track conversion unit in accordance with the prior art; 
           [0012]      FIG. 2  is a front-right isometric view of the track conversion unit of  FIG. 1 , without a track; 
           [0013]      FIG. 3  is a left-side elevation view of an extended track conversion unit highlighting a track extension in accordance with an embodiment of the present invention; 
           [0014]      FIG. 4  is a right-side elevation view of the extended track conversion unit of  FIG. 3 , without a track; 
           [0015]      FIG. 5  is a rear-left isometric view of the extended track conversion unit of  FIG. 3 , without a track; 
           [0016]      FIG. 6  is a top plan view of the extended track conversion unit of  FIG. 3 , without a track; 
           [0017]      FIG. 7  is a perspective view of the track extension as removed from the track conversion unit of  FIG. 1 , with idler wheels and trailing wheelset; and 
           [0018]      FIG. 8  is a perspective view of the track extension of  FIG. 7 , without the idler wheels and trailing wheelset. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    Referring to  FIGS. 1 and 2 , a track conversion unit in accordance with the prior art is generally shown at  10 . The track conversion unit  10  is a wheel-mount type conversion unit, for instance used in place of a wheel of an ATV. The track conversion unit  10  has a frame  12  (i.e., track frame  12 ), upon which is mounted a drive sprocket  14 . 
         [0020]    The frame  12  has a rear frame member  12 A, a base frame member  12 B and a front frame member  12 C. The drive sprocket  14  receives an output from a drive shaft of a vehicle, and transmits the output to a track  16  of the track conversion unit  10 . The track  16  is as an example a one-piece vulcanized belt, but may have numerous other configurations as well. A trailing wheelset  20  and a leading wheelset  21  combine with the drive sprocket  14  to tauten the track. Idler wheels  22  and idler sprockets  23  provide support to a bottom portion of the track. 
         [0021]    The trailing wheelset  20  is part of a wheelset assembly  24 . The wheelset assembly  24  has a telescopic arm  25  that is received in an open end  26  of the base frame member  12 B. A tensioning mechanism  27  is provided to lock the position of the wheelset  20  with respect to the base frame member  12 B to adjust the tension in the track, and to increase/reduce the footprint of the track on the ground. 
         [0022]    Referring to  FIGS. 7 and 8 , a track conversion unit equipped with a track extension is generally shown at  10 ′, and is essentially similar to the track conversion unit  10  of  FIGS. 1 and 2 , but with the track extension  30 . As such, like elements between the track conversion unit  10  of  FIGS. 1 and 2 , and the extended track conversion unit  10 ′ of  FIGS. 3 to 8  will bear like reference numerals. 
         [0023]    Referring to  FIGS. 7 and 8 , the track extension  30  has a frame  32  (i.e., extension frame  32 ). The frame  32  has a reinforcement arm  32 A and a base frame member  32 B. 
         [0024]    The reinforcement arm  32 A relates the base frame member  32 B to the rear frame member  12 A of the track conversion unit  10 . The reinforcement arm  32 A has a connector bracket  33  at a front end thereof. The connector bracket  33  clamps onto the rear frame member  12 A of the track conversion unit  10 , for instance by way of a fastener such as a bolt. A bottom end of the reinforcement arm  32 A is secured directly (e.g., welded) to the base frame member  32 B. 
         [0025]    Referring to  FIGS. 7 and 8 , the base frame member  32 B supports the idler wheels interfacing with the track and connects to the base frame member  12 B of the track conversion unit  10 . More specifically, the base frame member  32 B is typically a tube having a connector  34  protruding from its front end. The connector  34  is fitted into the base frame member  12 B of the frame  12 , and fasteners such as bolts are used to lock the base frame members  12 B and  32 B to one another. 
         [0026]    Axles  35  and  36  project radially from opposed sides of the base frame member  32 B. The axles  35  and  36  will respectfully support idler wheels  35 A and  35 B ( FIG. 7 ). 
         [0027]    The wheelset assembly  24  of  FIGS. 1 and 2  is inserted at a rear open end  37  of the base frame member  32 B. As such, the rear bending wheelset  20  is at the rear end of the track extension  30 , with the adjustment mechanism  27  provided to allow the telescopic adjustment of the wheelset assembly  24  with respect to the extended track conversion unit  10 ′. 
         [0028]    An attachment bracket  40  is part of the track conversion unit  10  and is provided so as to interface the frame  12  to suspension members or like structural members. 
         [0029]    Now that the track extension  30  has been described, its installation to an existing track unit, such as the track conversion unit  10 , is described. 
         [0030]    The track conversion unit  10  of  FIG. 1  has the track  16  removed. This may be performed by loosening the trailing wheelset  20  using the tensioning mechanism  27 . Accordingly, once the track  16  is removed, the track conversion unit  16  has the configuration illustrated in  FIG. 2 . 
         [0031]    In order to assemble the extended track conversion unit  10 ′ of  FIG. 3 , the track extension  30  is mounted to the track conversion unit  10 . In a first step, the wheelset assembly  24  is separated as a whole from base frame member  12 B (including the tensioning mechanism  27  being separated from an axle of idlers wheels  22 ), leaving the open end  26  of the base frame member  12 B exposed. 
         [0032]    The track extension  30  illustrated in  FIG. 7  is mounted to the frame  12  of the track conversion unit  10 . More specifically, the connector  34  is matingly engaged in the open end  26  of the base frame member  12 B, whereas the bracket  33  is mounted to the rear frame member  12 A. At both these locations, the track extension  30  is fastened to the frame  12  so as to block rotation of the base frame member  32 B with respect to the base frame member  12 B. 
         [0033]    Accordingly, as shown in  FIGS. 4 and 5 , the track extension  30  is secured to the frame  12  at two different locations. As such, an extended frame is formed with suitable structural rigidity to support a track, and to sustain the forces involved with the track. The materials and components used to fabricate the track extension must therefore be suited for such harsh conditions. 
         [0034]    Once the track extension  30  has been mounted to the track conversion unit  10 , the wheelset assembly  24  is mounted to the rear open end  37  of the base frame member  32 B. This is performed by inserting the telescopic arm  25  of the wheelset assembly  24  into the rear open end  37 , and fastening these components to one another, to provide the extended track conversion unit  10 ′ illustrated in  FIGS. 4 and 5 . 
         [0035]    The track  16 ′ is then mounted about the extended track conversion unit  10 ′ in the manner illustrated in  FIG. 3 . More specifically, the track  16 ′ is arranged so as to be properly engaged with the drive sprocket  14 . The track  16 ′ has a greater periphery than the track  16 , as a footprint of the track conversion unit is increased by the configuration illustrated by  10 ′. 
         [0036]    The position of the wheelset assembly  24  is adjusted so as to tension the track  16 ′. This is performed by adjusting the tensioning mechanism  27  (which cooperates with the axle  36 ) until suitable tension is attained for the track  16 ′. The extended track conversion unit  10 ′ is then ready to be used. 
         [0037]    It is pointed out that the track conversion unit  10 ′ may be returned to the configuration illustrated by  10  in  FIGS. 1 and 2 , if it is required to reduce the footprint of the track. As such, operators of vehicles using tracks can have sets of tracks adapted for different conditions, by way of the track extension  30  enabling the use of longer tracks. 
         [0038]    The track extension  30  is advantageously available as a retrofit kit that allows the increase of the footprint of existing track systems. It is pointed out that the track extension described at  30  is shaped and sized so as to fit with the components of the track system. In the embodiment described in  FIGS. 3 to 8 , the wheelset assembly  24  does not need to be altered to be used with the track extension  30 . Moreover, the track extension  30  does not affect the relation between the track conversion unit  10  and the drive shaft of the vehicle, as all moveable components of the track extension are idlers. 
         [0039]    Referring to  FIG. 6 , it is seen that the sprocket  14  is centrally positioned between left and right idlers  20 ,  21 ,  22 ,  35 A and  36 A and sprockets  23 . Accordingly, the rear and front frame members  12 A and  12 C are bent to allow the sprocket  14  to be offset. It is therefore seen from  FIG. 6  that the reinforcement arm  32 A is slanted to appropriately match the shape of the frame  12 . 
         [0040]    Although the track extension  30  is shown as being used with a track conversion unit  10 , it is contemplated to provide such track extensions with other types of tracks (e.g., agricultural, army such as tanks, industrial, recreational vehicles amongst others). For instance, vehicles with permanent tracks may benefit from an increased footprint, whereby it is desired to provide extensions for all types of track systems. The track extension  30  has a frame that is adapted to be secured to an existing frame to provide the structural integrity required to support a track and to sustain the forces involved with the drive of a track on various terrains. The track extension  30  has idlers to support the track opposite the ground. The track extension  30  is adapted to support a trailing wheelset that will define the limits of the footprint, with the trailing wheelset being optionally part of the original track system to which the track extension  30  is added. Alternatively, the track extension  30  may have its own trailing wheelset. Finally, the tensioning mechanism (e.g., the one illustrated at  27  in  FIGS. 1 to 8 ) provides adjustment in the tension of the track by the adjustment of the footprint of the track. 
         [0041]    It is also pointed out that the track extension  30  may alternatively be used at a leading end of a track system, although the embodiments of the track extension illustrated in  FIGS. 1 to 8  show the track extension at a trailing end of the track system.