Abstract:
A truck track drive can include two rollers. The truck track drive can also include a tread configured to pass over top and bottom of a dual rear wheel assembly on a truck and to be moved by rotation of the dual rear wheels. The track drive can also include a compulsory drive unit.

Description:
Embodiments relate generally to track drives for vehicles, and, more particularly to a track drive for a truck. 
     In winter, trucks with dual rear wheels may be prone to losing traction on snow or ice. 
     One or more embodiments were conceived in light of the above-mentioned limitations or problems, among other things. 
     An embodiment can include a track drive apparatus for a truck having a track belt that passes around a rear wheel set (e.g., two wheels) and around a roller toward the forward end and a roller toward the backward end. The belt is kept in tension by a flexible rod coupled to both the front roller and the back roller. 
     Another embodiment can include a track drive for a truck having compulsory drive apparatus for driving the track drive tread from a chain and sprocket coupled to the wheel and the rear roller so as to be moved (or driven) by rotation of the vehicle tire. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a truck equipped with an exemplary track drives in accordance with at least one embodiment. 
         FIG. 2  is a diagram of an exemplary track drive in accordance with at least one embodiment. 
         FIG. 3  is a diagram of an exemplary track drive motion in accordance with at least one embodiment. 
         FIG. 4  is a diagram of a tread of an exemplary track drive in accordance with at least one embodiment. 
         FIG. 5  is a diagram of an exemplary roller in accordance with at least one embodiment. 
         FIGS. 6A and 6B  are diagrams of an exemplary track drive having a compulsory drive feature in accordance with at least one embodiment. 
         FIGS. 7A and 7B  are diagrams of an exemplary track drive having a compulsory drive feature in accordance with at least one embodiment. 
         FIG. 8  is a diagram of an exemplary track drive having a mud/debris shield in accordance with at least one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In general, an embodiment can include a truck track drive that is driven by an existing wheel and tire of a vehicle, without a need to remove the wheel or tire. The truck track drive unit can fit around an existing dual rear wheel assembly of a truck and is powered by the rotation of the wheel/tire. Alternatively, a compulsory drive embodiment can be used. 
       FIG. 1  shows a truck  100  equipped with an exemplary truck track drive  102 . The track drive  102  is shown attached to the dual rear wheel assembly. 
     In operation, as the wheels of the truck  100  turn, tracks on each of the dual rear wheel assemblies are moved. 
       FIG. 2  shows the truck track drive  102  in greater detail. The track drive  102  includes drive teeth  104  on an outer tire, tread cleats  106 , tread belt  108 , tension rod  110  and roller  112 . 
     The tension rod  110  can include a first portion and a second portion, each having a threaded end. The threaded ends can be mated with a spacer  111 . The spacer  111  can include internal thread configured to mate with the threaded end portions of the tension rod portions. The spacer can be used to increase tension in the rod by rotating the spacer in a first direction and to decrease tension in the rod by rotating the spacer in a second direction. 
     All metallic components and body can be made of steel. The protective panels (see below) can be made from plastic (or from a thin sheet of metal). The bearings can be standard. The tread (or caterpillar) can be made of resin-fabric or resin-metal.  FIG. 4  shows a simplified tread having resin-fabric tape  108 , on which, with the aid of the bolts or the rivets, are mounted the cleats in the form of longitudinal plates  106 , between which there are cuts  402  for the entry in them of the hooks of  104  special external casings. 
       FIG. 3  is a diagram of an exemplary track drive  102  motion. As the truck moves forward  302 , the track drive unit rotates  304  about the wheel axle. 
       FIG. 4  is a diagram of a tread of an exemplary track drive tread showing the openings  402  in the tread belt configured to accept the outer tire drive teeth  104 . It can also be seen that the tread is the width of two tires (shown by dotted lines  404 ). 
       FIG. 5  is a diagram of an exemplary roller  112  having bearings  502 . The roller  112  would have a width  504  to accommodate the width of the tread. 
       FIGS. 6A and 6B  are diagrams of an exemplary track drive  600  having a compulsory drive feature that includes a wheel assembly  602 , a toothed gear  604  disposed between the rear wheels and a tread having indentions on an inner circumference configured to mate with the toothed gear  604 . 
       FIGS. 7A and 7B  are diagrams of an exemplary track drive  700  having a compulsory drive feature including a chain  702 , a tread tension arm  704 , a tensioner platen  706 , a tread  708 , a driven gear  710 , a roller  712  and a drive gear  714 . 
     In operation, the drive gear  714 , disposed between the rear wheels of a rear wheel assembly, drives the chain  702 , which in turn powers the driven gear  710  coupled to the roller  712 , which powers the tread  708 . The tensioner platen  706  acts to keep a desired tension on the chain  702 . 
       FIG. 8  is a diagram of an exemplary track drive  102  having a mud/debris shield  802  to help prevent mud, dirt, debris, snow, ice or the like from interfering with the operation of the track drive. In addition to the partial shield shown, a full shield could be used that covers all or nearly all of the track drive and reduces intrusion of mud, debris, snow, ice or the like. The full shield could be used on both an exterior and interior of the track drive. It will be appreciated that when used on an interior of the track drive a partial or full shield may need to be formed in two parts in order to be placed around the axle of the truck. 
     It is, therefore, apparent that there is provided, in accordance with the various embodiments disclosed herein, truck track drives. 
     While the invention has been described in conjunction with a number of embodiments, it is evident that many alternatives, modifications and variations would be or are apparent to those of ordinary skill in the applicable arts. Accordingly, Applicant intends to embrace all such alternatives, modifications, equivalents and variations that are within the spirit and scope of the invention.