Abstract:
A land vehicle has a flexible central frame member which extends from a large front roller to a smaller rear roller, and is encircled by a flexible looped belt having projecting treads. An engine mounted above the belt drives the front roller, and two bogie wheels engage the belt within valleys formed in the treads. Two boot supports are fixed to the central frame member which support the feet of a standing rider. Rollers fixed to the central frame member support the belt as it travels around the frame. The minimal extent of the frame outside the belt exposes a substantial length of the belt edge to engagement with the ground, making it possible to control the vehicle by twisting and tipping, in a manner similar to the control of a conventional unpowered snowboard. A trailer or sled may be connected to the rear of the vehicle for towing cargo.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not applicable.  
         STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT  
         [0002]    Not applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    The present invention relates to vehicles in general, and in particular to compact vehicles intended for use by a single operator.  
           [0004]    The snowboard has enjoyed success as a recreational vehicle, providing the exhilaration of downhill skiing, with the added elements of control provided by having only a single board to which both of the rider&#39;s feet are connected. Like its predecessor, the skateboard, the snow board is generally controlled without poles or other accessories, instead relying on the rider&#39;s posture, movement of center of gravity, and by adjusting the position of the board by lifting or moving the user&#39;s feet where connected to the board.  
           [0005]    Unlike a skateboard, a conventional snowboard is substantially limited to downhill travel on snow covered terrain. Several approaches to motorizing a snowboard have been suggested. In one approach, a motor driven continuous belt or track is mounted to a wide ski, and travels beneath the ski to advance the board. These vehicles use the track as an accessory to the slipping surface of the ski for downhill travel. Another approach employs a curved frame with an encircling track, with a center mounted motor. However, prior art devices, because of their construction, have sacrificed some of the control aspects conventionally used by the snowboard rider, thereby failing to fully make use of the skills developed by the snowboard rider, or compromising the maneuverability of the vehicle.  
           [0006]    What is needed is a powered vehicle which simulates the controllability of a snowboard, while being capable of being used on upwardly inclined or level surfaces, whether covered by snow or not.  
         SUMMARY OF THE INVENTION  
         [0007]    The personal tracked vehicle of this invention has a flexible central frame member which extends from a large front roller to a smaller rear roller, and which is encircled by a flexible looped belt having projecting treads. A gasoline engine mounted above the belt drives the front roller, and two bogie wheels engage the belt within valleys formed in the treads. Two boot supports are fixed to the central frame member, and support the feet of a standing rider. Rollers fixed to the central frame member support the belt as it travels around the frame. The minimal extent of the frame outside the belt exposes a substantial length of the belt edge to engagement with the ground, as well as the stiff lips of the rollers, making it possible to control the vehicle by twisting and tipping, in a manner similar to the control of a conventional unpowered snowboard. A trailer or sled may be connected to the rear of the vehicle for towing cargo, and by provision of a tiller, the sled may be used to steer the vehicle.  
           [0008]    It is an object of the present invention to provide a motorized vehicle which is controlled in a fashion similar to a conventional snowboard.  
           [0009]    It is another object of the present invention to provide a personal vehicle for operation on snow, grass, mud, and other surfaces.  
           [0010]    It is a further object of the present invention to provide a highly maneuverable vehicle for operation by a single standing rider.  
           [0011]    It is an additional object of the present invention to provide a compact motorized vehicle capable of hauling cargo in a sled.  
           [0012]    It is also an object of the present invention to provide a tracked vehicle capable of descending hills under gravity, and of traveling on level ground under power.  
           [0013]    It is yet another object of the present invention to provide a tracked vehicle with a very low center of mass.  
           [0014]    It is a still further object of the present invention to provide a personal vehicle which is readily steered while carrying cargo.  
           [0015]    Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a perspective view of the personal tracked vehicle of this invention, showing a rider thereon.  
         [0017]    [0017]FIG. 2 is a fragmentary isometric view, partially broken away in section, of the rear of the personal tracked vehicle of FIG. 1.  
         [0018]    [0018]FIG. 3 is a fragmentary isometric view, partially broken away in section, of the front portion of the personal tracked vehicle of FIG. 1.  
         [0019]    [0019]FIG. 4 is an exploded isometric view of the personal tracked vehicle of FIG. 1.  
         [0020]    [0020]FIG. 5 is a fragmentary isometric view of the vehicle of FIG. 1 towing a trailer.  
         [0021]    [0021]FIG. 6 is a fragmentary side elevational view, partially broken away in section, of the vehicle of of FIG. 1 towing an alternative embodiment trailer.  
         [0022]    [0022]FIG. 7 is a fragmentary cross-sectional view of an alternative embodiment vehicle of this invention, have side rollers mounted on flexible axles. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    Referring more particularly to FIGS.  1 - 7 , wherein like numbers refer to similar parts, a personal tracked vehicle  20  is shown in FIG. 1. The vehicle  20  has a frame  22  which supports a flexible looped belt  24  which is driven by a small gasoline engine  26  to transport a single rider  28 .  
         [0024]    As shown in FIG. 4, the frame  22  is constructed around a central frame member  30  which extends in the front to back direction and which is sturdy but flexible. The central frame member  30  is preferably comprised of a laminate of a plurality of layers of material or a composite material such as reinforced plywood or fiberglass, or HDPE plastic reinforced with a light tension spring. Although illustrated as of a constant thickness, the central frame member  30  is preferably constructed of a tapered member which is narrower at the ends and thicker at the center, for example, extending from a center region that is about one inch thick, to about ⅜ inch thick at the ends near the front and rear of the vehicle  20 . A front boot support  32  and a rear boot support  34  are fixed to the central frame member  30 . Each boot support  32 ,  34  has a boot bracket  36  with a lower plate  38  and two upwardly extending side plates  40 . Each boot bracket lower plate has a roller slot  42 , and is connected by fasteners to the underside of the central frame member  30 .  
         [0025]    The belt  24  is mounted on the frame to define an upper run  44  which extends over the central frame member  30 , and a lower run  46  which extends beneath the central frame member. The side plates  40  of the boot brackets  36  extend upwardly above the level of the belt upper run  44 . A boot plate  48  is fastened between each pair of side plates  40  and is supported by the side plates above the belt  24 . Each boot plate  48  has two parallel slots  54  formed therein. A boot binding  50  is adjustably fastened to each of the plates  48  by fasteners  52  which extend into the boot plate slots  54  to permit the sliding and adjustable positioning of the bindings  50  with respect to the boot plates. The shoes or boots  56  of the rider  28  are securely fastened within the bindings  50  as shown in FIG. 1. Any conventional snowboard or ski type binding may be employed.  
         [0026]    The belt  24  may be formed of a conventional flexible belt material, for example, rubber or polymer with strands of reinforcing material. The belt  24  extends between a rear roller  58  mounted by a slack take-up assembly  60  to the frame  22 , to a front roller  62  which extends frontwardly from the frame on two opposed front roller arms  64 . The rear roller  58  is approximately 2½ inches in diameter, while the front roller  62  is substantially larger, for example 7 inches in diameter. The large diameter of the front roller permits the vehicle to pass over sticks, logs, trail debris, and rough terrain. The front roller  62  has lips  76  on each side of the belt which protrude slightly above the level of the belt. The rear roller  58  is also provided with lips  78  on each side of the belt.  
         [0027]    For optimal performance, the vehicle  20  provides substantial potential engagement between the edges  66  of the belt  24  and the supporting surface, whether snow, grass, gravel, mud or blacktop. This edge engagement greatly contributes to giving the vehicle  20  the feel and controllability of a conventional snowboard. The effective maneuverability of the board is also contributed to by the lips of the front roller, the rear roller, and the side rollers  68 . The belt  24  is supported at its edges as it travels from the front roller  62  to the rear roller  58  by six side rollers  68 . Each side roller  68  has a cylindrical body  70  and a radially protruding lip  72 . The side roller  68  bodies  70  are somewhat larger than the rear roller, for example about three inches in diameter. The smaller diameter rear roller is mounted with its axis elevated above the axes of the side rollers, so that the belt extends upwardly from the ground as it approaches the rear roller, as shown in FIG. 6, making the rear of the board easier to kick around by the rider. The rigid protruding lips of the rollers not only help to guide the belt, but also allow the rider to dig an edge in on an icy surface, contributing to control of the vehicle. The lips may protrude about ⅜ of an inch from the bodies of the rollers.  
         [0028]    Each side roller  68  is rotatably mounted to a block  74  which is fastened to the underside of the central frame member  30 . Rigid axles are fixed to the blocks  74 , and bearings within the rollers  68  mount the side rollers for rotation about the fixed axles. The side rollers  68  are mounted to the central frame member in opposed pairs. The side rollers  68  in a pair are spaced sidewardly from one another. Each side roller  68  body  70  has portions which engage the belt as it travels over the side rollers, and portions which engage the belt as it travels beneath the side rollers. The belt  24  is driven by frictional engagement with the front roller  62 , and hence the apparatus is very simple. Should momentary slippage of the belt occur, the drive will still perform satisfactorily.  
         [0029]    The appropriate tension is applied to the looped belt  24  by the slack take-up assembly  60 . The slack take-up assembly  60  is comprised of two side tubes  90 , shown in FIG. 4, which are fastened to the central frame member  30  rearwardly of the rear boot support  34 . Two roller arms  92  are slidably received within the side tubes  90 . The roller arms  92  have side ears  94  between which the rear roller  58  is mounted. Threaded bolts  96 , shown in FIG. 2, extend between tabs  98  fixed to the side tubes  90  and portions of the roller arms  92 . Rotation of the bolts  96  adjusts the spacing between the frame  22  and the rear roller  58  permitting the take-up of slack in the belt  24 . Alternatively, coil springs could be used to set the tension on the belt in place of the take up assembly.  
         [0030]    The front roller  62  is rotatably mounted between two front roller arms  64  which extend frontwardly from a motor support assembly  100  which forms a part of the frame  22 . The motor support assembly  100  has a rear cross member  102  which is fixed to the central frame member  30 . Two side members  104  extend upwardly from the rear cross member  102  and receive a bogie wheel axle  106  therebetween. Two stiff rubber or plastic bogie wheels  108  are mounted to the axle  106 . The bogie wheels  108  are fixed to the axle  106 , while the axle rotates on the side members  104 . The belt  24  passes beneath the bogie wheels  108  and around the front roller  62 . The front roller  62  is substantially larger in diameter than the rear roller and the side rollers. The bogie wheels  108  cause the belt  24  to wrap around more than 180 degrees of the circumference of the front roller  62 , preferably in a range of about 210 to 270 degrees of wrap. The bogie wheels mounted above the belt enables the looped belt to have a very small height, around 3 three inches. This low profile contributes to the maneuverability of the vehicle. The rider, standing just above the belt and rearward of the motor, is brought very low to the ground. It is important to note that operation of this vehicle requires the rider to be constantly aware of his balance, and to maintain his center of gravity within the footprint of the tread. The low profile of the vehicle contributes to the rider keeping the combined center of gravity of rider and vehicle within the footprint of the tread, and thus to resist the tendency to tip over. The higher the center of mass, the more reduced is the angle which the rider can tilt before the board will tip over. Hence, the low profile belt allows for a greater angle of tilt of the rider in steering, and hence greater maneuverability. The greater diameter of the front roller aids the vehicle  20  in advancing over raised obstacles and changes in elevation.  
         [0031]    As shown in FIG. 4, the belt  24  has an array of parallel treads  110  which extend entirely around the belt. Each tread has three segments: two edge segments  112  positioned adjacent the edges of the belt  24 , and a center segment  114  positioned between the two edge segments. The edge segments  112  are spaced from the center segments to define valleys  116  of zero height projection. At the valleys, the belt may be from ⅛ to ¼ inch thick, and is preferably about {fraction (3/16)} inch thick. The valleys of all the treads  110  are aligned to allow the bogie wheels  108  to pass through the valleys. The segments  112 ,  114  of the treads are beveled. Thus the bogie wheels tend to retain the belt  24  in proper side to side orientation on the frame  22 . The beveled outer edges of the edge segments  112  contribute to slip from side to side when shifting weight in snow or soft materials.  
         [0032]    Two center rollers  118  of the same diameter as the side rollers are rotatably mounted between pairs of blocks  120  fastened to the underside of the central frame member  30 . The center rollers  118  project upwardly through roller slots  122  formed in the central frame member  30 . If positioned above the boot support lower plates  38 , as illustrated, the lower plates must also be provided with slots  42  thereby permitting the center rollers  118  to engage both the upper run  44  and the lower run  46  of the moving belt. It should be noted that, in certain designs, it may be desirable to position a roller on the underside of the boot plate  48  to reduce frictional engagement between the top surface of the belt and the boot plate.  
         [0033]    A motor  26 , for example a two cycle 5 hp gasoline engine with a centrifugal clutch, is mounted to upper crossbars  128  extending between side plates  130  of the motor support drive sprocket  132  with a 7:1 or 6:1 reduction. The front roller may be rotated at from about 100 to 1500 rpm. As indicated in FIG. 3, the drive sprocket is connected by a chain  136  in driving relation to a front roller sprocket  134  fixed to the front roller  62 . Rotation of the drive sprocket at its top speed would result in a vehicle speed of about 20-40 mph. Because of the centrifugal clutch with which the motor is provided, the vehicle  20  will freewheel when going downhill.  
         [0034]    As shown in FIG. 1, the rider mounts the vehicle  20  and fastens the bindings  50  about his boots  56  and takes in one hand a velocity control stick  138  which is connected by a flexible conduit  142  to the motor  26  and a brake caliper  140  operating with respect to the front roller sprocket  134 . The velocity control stick  138  has two controls: a thumb operated throttle and a finger or hand operated brake. Both controls operate through cables  144  which extend through the conduit  142  to the engine throttle and to the brake caliper  140 , shown in FIG. 3. When actuated, the brake caliper  140  grips the front roller sprocket  134  to slow down the vehicle  20 .  
         [0035]    The vehicle  20  is particularly advantageously employed on snow-covered surfaces because of the wide footprint of the track. Used by itself the vehicle  20  can travel at high speeds and is very maneuverable in a fashion similar to the operation of a conventional snowboard. However, the vehicle  20 , as shown in FIGS. 5 and 6, may also be used for hauling cargo by the attachment of a sled. In a first embodiment, shown in FIG. 5, the sled  146  is a fiberglass assembly having a frontwardly extending tongue  148  which is connected by a pin  150  to a rigid yoke  152  which extends rearwardly from the rear roller arms  92 . The vehicle  20  with the sled  146  attached is steered and operated in a conventional fashion just as a snowboard would be operated.  
         [0036]    An alternative embodiment sled  154 , shown in FIG. 6, has a frontwardly extending tongue  156  which connects to the yoke  152  extending rearwardly from the vehicle  20 , but is steered by a tiller  158  which extends upwardly from the sled tongue  156  and which has a front to back extending handle  160  which is grasped by the rider  28 . When the sled  154  is attached to the vehicle  20 , steering is accomplished by rotating the handle  160  to turn the sled and thereby modify the direction of the vehicle. The sled is preferably provided with a downwardly protruding central strip  162  which extends below the general underside  164  of the sled into engagement with the snow, mud, or surface over which the sled travels, and restricts the slipping of the sled on the surface, allowing the sled to act more effectively as a steering mechanism. When the vehicle  20  is pulling the sled, with the rider holding the tiller, the sled acts like a rudder, forcing the tail of the vehicle around, steering it, without requiring the rider to shift his center of mass, or to kick around the rear of the vehicle. Such a lower energy steering arrangement is appropriate for using the vehicle for utility purposes, such as towing ice fishing supplies, camping equipment, and the like.  
         [0037]    It should be noted that, for clarity of illustration, the vehicle  20  has been shown in most figures without appropriate protective coverings. In a preferred embodiment moving parts of the vehicle such as the belt and the motor will be shielded from contact with the operator. A fiberglass cowling  165 , as shown in phantom lines in FIG. 6, will preferably extend over most of the top surface of the belt and the motor on the motor support assembly. The cowling may be removably fastened to the central frame member and the non-moving parts of the vehicle such as the boot supports, the motor support assembly, and the rear roller arms.  
         [0038]    As shown in FIG. 7, an alternative embodiment vehicle  166  may be provided with side rollers  168  which are mounted on flexible axles  170 . The axles  170  may be formed of carbon fiber or spring steel. The side rollers  168  have bearings which rotate on the axles  170 . The axles  170  are fixed at one end to a block  172  which is connected to the underside of the center frame member  174 . The axles  170  project from the block  172 , and a stop  176  is positioned above each axle to limit the upward deflection of the axle. The flexible axles  170  on the side rollers contribute to a vehicle which is more maneuverable, and controllable, as the outer edges of the belt  178  will conform more to the surface over which the vehicle  166  is traveling.  
         [0039]    It should be noted that the vehicle  20  could be longer or shorter than illustrated, with a greater or lesser number of side rolls. Furthermore, although the boot supports have been illustrated as being assembled from plates, they may also be formed as unitary aluminum extrusions, or as a lower U-shaped extrusion with an attached top plate. Moreover, the motor, although disclosed as being attached at the front of the vehicle, could also be mounted between the front and rear boot supports. In addition, the looped belt could be split into two parallel belts running in the same direction.  
         [0040]    It is understood that the invention is not limited to the particular construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the following claims.