Abstract:
An improved Pinewood Derby (and derivatives) Track is disclosed being composed of plastic. In the preferred embodiment a plastic extrusion two lanes wide and eight feet long is joined to additional similar sections by shorter identical extrusions to make a track of virtually any width and length. The result is a very low weight, very uniform, very low maintenance track that can be assembled without tools.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not Applicable  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable  
         REFERENCE TO A MICROFICHE APPENDIX  
         [0003]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    The present invention relates to the Pinewood Derby. The Pinewood Derby is generally a youth activity (most commonly a Cub Scout activity) in which small, typically 5 ounce, cars run a gravity powered race on a track that commonly is from 2 to 8 lanes wide and from 32 to 50 feet long. Typically, the youngsters with the help of a parent carve the cars, which begin life as a block of wood, four wheels and four nails (axles).  
           [0005]    The original track design which dates to the early 1950&#39;s uses a 4′ by 8′ sheet of plywood, cut into 4 lengths about 1 foot wide, joined end to end and further provided with lath strips in the center of each lane which act as car guides. A stand is provided at the start to create a “hill”. The lath is lifted after the finish and covered with carpet to provide a stopping means. The result is a three lane, 32′ track which propels the cars at about 15 MPH and produces start to finish times in the 2.6 second range.  
           [0006]    [0006]FIG. 1 “PINEWOOD DERBY TRACK PLANS” shows a widely published track plan that is very commonly used by individuals to build the track. FIG. 2 “KubKar Track Design” is a less detailed version of essentially the same plans as published in Canada where the Pinewood Derby goes under the name “Kub Kar Rally” Other common Pinewood Derby derivative names include “Awana Grand Prix”, “RA Racer Derby” and “Shape N Race”.  
           [0007]    A design patent (D384,225) exists for a Pinewood derby car stand. There are no known patents related to Pinewood Derby Tracks. In addition to the two figures referenced above, several Internet sites show alternative methods of constructing wooden tracks and several manufacturers offer tracks constructed of various types of plywood or based on an aluminum extrusion with a user created base. One manufacturer has a system that is basically a kitchen counter top construction supported by a steel frame and another uses particle board that has been covered with a plastic laminate (Formica®)).  
           [0008]    [0008]FIG. 1 and FIG. 2 are mechanical drawings of current practice. Casual review will reveal the need for precision carpentry, detailed assembly and the many small nuts, bolts, hinges, dowels, brads, glue, etc. Note: Since FIG. 1 and FIG. 2 represent prior art and are not under the control of the inventor, they may not meet USPTO Drawing Guidelines.  
           [0009]    The source for FIG. 2 is available at:  
           [0010]    http://www.geocities.com/Yosemite/Gorge/1066/kubkartrack. GIF  
           [0011]    Additional track construction information is available at:  
           [0012]    http://www.geocities.com/Heartland/Plains/8340/track.htm  
           [0013]    http://www.rahul.net/mcgrew/derby/track  
           [0014]    Commercial track Internet sites include:  
           [0015]    http://www.pinewoodderbytrack.com  
           [0016]    http://www.indyproducts.com  
           [0017]    After the letters ‘com’ Internet addresses above are case sensitive. Not all manufacturers have Internet sites.  
           [0018]    Some of the problems with the original basic design are:  
           [0019]    1. It is heavy. The typical weight of a three lane track is 60 pounds or 15 pounds per 8 foot section. 4 lane and 6 lane tracks are proportionally heavier. This makes it difficult to assemble, carry and/or store.  
           [0020]    2. It is wood. It can splinter and warp. It needs painting and maintenance, especially of the joints between sections.  
           [0021]    3. Assembly, especially of the joints, requires lots of small, easily lost, parts as well as tools. The screws and nuts can also protrude below the track and gouge the floor, or pull through the surface if it is not of high quality.  
           [0022]    4. Construction, unless you buy a commercial track and even if you buy some of the commercial tracks, requires a skilled craftsman.  
           [0023]    5. The center guided lath method causes some cars to rub and lose speed.  
           [0024]    6. The braking mechanism is ineffective.  
           [0025]    7. The starting mechanism is not appropriate for many timing systems.  
           [0026]    Over the years changes have been made to the design both by individuals and by the companies who market commercial tracks or track kits. These changes include:  
           [0027]    1. Changing from center guided using lath to edge guided using rectangular strips.  
           [0028]    2. Covering the plywood with plastic laminate (Formica®) or similar hard surface.  
           [0029]    3. Changing the type of plywood or using MDF, chipboard, waferboard or hardboard.  
           [0030]    4. Changing the section-to-section fastening method.  
           [0031]    5. Building solid sides along the entire track and/or making the track more of a constant slope.  
           [0032]    6. Using an aluminum extrusion for the lanes with a metal or wooden support structure.  
           [0033]    7. Changing the number of lanes and/or the length.  
           [0034]    8. Adding hills or loops.  
           [0035]    9. Adding a foam block to stop the cars.  
           [0036]    While some of these changes are fairly innocuous, most are designed to add a degree of reliability or maintainability but unfortunately also add additional weight.  
           [0037]    It is the object of the present invention to overcome the problems inherent in the original design as well as some of the problems created in previous attempts to improve upon the original design.  
           [0038]    Other objects of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.  
         BRIEF SUMMARY OF THE INVENTION  
         [0039]    A Pinewood Derby Track constructed almost exclusively from plastic is set forth. In the present invention, the plastic is an extrusion although other fabrication methods could be used. In the present invention the extrusion is two lanes wide by 8 feet long although other combinations are also possible. More particularly, the extrusion is designed with an interlocking edge so that additional lanes may be added as needed. In addition, the extrusion is designed with an interlocking means such that a shorter section may be inverted and used to lock two long sections in edge-to-edge alignment. The shorter section may also be used to hold one set of two sections to an additional set of two sections in end-to-end alignment for the purpose of making the track longer.  
           [0040]    The object of the present invention is to drastically reduce weight (approximately 50% overall, only 3.5 pounds per individual full section), eliminate the need to paint or otherwise finish the track, eliminate splinters, eliminate warping and provide a very smooth surface with consistent and excellent alignment in all planes. A further object of the present invention is to allow a track to be assembled without tools and without any small parts or gluing. Because of the unique interlocking design, assembly can be accomplished by virtually anyone without the need for a skilled craftsman. The preferred embodiment is an edge guided design that includes the side rails eliminating the separate wooden strip guide rails of the modified conventional design.  
           [0041]    For reference, the overall track design also includes an improved stopping mechanism, an improved starting mechanism, a light weight, PVC tubing, support structure and some other features that remove objections or add improvements to the original design but which are not a part of this application or claims.  
           [0042]    These and other advantages and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0043]    [0043]FIG. 1 illustrates the conventional Pinewood Derby Track Plan.  
         [0044]    [0044]FIG. 2 illustrates an alternative, although very similar, track plan.  
         [0045]    [0045]FIG. 3 illustrates a preferred extrusion profile for the present invention.  
         [0046]    [0046]FIG. 4 illustrates two long extrusions joined by a third inverted shorter extrusion.  
         [0047]    [0047]FIG. 5 illustrates the joining of four sections edge-to-edge and end-to-end.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0048]    Understanding the present invention begins with FIG. 3, which is a profile of the preferred extrusion. Note that the profile at  1  is the inverse of the profile at  2 . This provides the edge-to-edge alignment when two or more sections are used. Edge guiding of the cars is accomplished by  1 ,  2  and  3  with the cars running in the flat areas  4  and  5 . While FIG. 3 shows the preferred embodiment of a two lane extrusion profile, there is no practical reason that the profile could not be for one lane or multiple lanes. The interlocking ‘L’  6  and reverse “L”  7  shaped bosses are used when multiple full length sections are joined edge-to-edge and end-to-end as described later.  
         [0049]    The alignment of two full length sections created by  1  and  2  is only constrained in the vertical direction. Constraint in the horizontal direction is shown in FIG. 4. In FIG. 4 the first full-length section  10  is joined to a second full length section  11  by a third short (typically less than one foot) inverted section  12 . The addition of the third short section  12  constrains the joining of the two full length sections in the horizontal direction. For illustration purposes we may now consider that we have created a four lane by eight foot track segment using  10 ,  11  and  12 . If we wish a six lane (or more) track, we need only repeat the addition of a two lane full length section  11  and an additional short section  12  in the same manner (not shown), repeating the process as often as desired to make a track of practically any width.  
         [0050]    However, we also need a track of longer length. Returning to our four lane by eight foot track segment, it can be seen in FIG. 5, which shows a portion of the underside of a track, that if a single short section  12  is positioned at the joint  13  between the previous full sections  10  and  11 , and two additional full length sections  14  and  15 , it will provide the needed alignment and constraint in all directions excepting only the potential for the sections to pull apart in the direction of car travel.  
         [0051]    In addition, means are required to insure that the short section  12  remains reasonably centered over the section end-to-end joint  13 . This means is provided by adding feet  16  mounted (in the preferred embodiment—solvent welded during manufacture) to the full length track sections and positioned so as to keep the short section  12  centered about the section end-to-end joint  13 .  
         [0052]    The ability to pull the section end-to-end joint apart is a necessary part of track assembly/disassembly. During racing it is prevented by the simple addition of rubber bands  17  (only one shown for clarity) of sufficient size and strength to keep the end-to-end joints in contact and installed from foot to foot  16 .  
         [0053]    In the preferred embodiment the feet  16  are at least as high as the short length of extrusion  12 . The feet  16  are further spaced over the length of each section as necessary (not shown) so that the entire track remains level (with the exception of the area where the support means provides the initial “hill”.)  
         [0054]    In a manner similar to that used to make multiple lanes, an additional short section  12  and additional full length sections can be used in a repetitive process to extend the track end-to-end to any desired length.  
         [0055]    When the present invention is produced for the Cub Scout market, the preferred embodiment uses the Cub Scout colors of yellow and blue. However other colors may be chosen without departing from the spirit and scope of the present invention.  
         [0056]    When the present invention is produced for the Cub Scout market, the preferred embodiment uses dimensions similar to those of FIG. 1 and FIG. 2. Additionally, some dimensions are used to control the stiffness of the track and may vary depending on the particular plastic formulation used. However, alternate dimensions may be chosen without departing from the spirit and scope of the present invention.  
         [0057]    In view of the above detailed description of the of the present invention and associated drawings, other modifications and variations will now become apparent to those skilled in the art. It should be apparent that such other modifications and variations may be effected without departing from the spirit and scope of the present invention.