Abstract:
A flexible ski which is molded in one piece entirely of Ultra High Molecular Weight Polyethylene plastic. The adjustable flex ski is made up of a ski body which forms the majority of the invention and provides the base from which the other components are formed. This ski body is molded in a flat configuration. The front portion of this ski is given a pre-load function by bending the forward most portion of the ski body in an upward fashion. It is then held in this position by the use of pre-load bar which extends pivotally rearward from the tip of the ski to a ski saddle located on the upper center surface of the ski body. This saddle provides various attachment points for the pre-load bar and can thus, vary the amount of pre-load on ski. The saddle is also supplied with an attachment point for mounting the ski on the vehicle. This configuration allows the tip of the adjustable flex ski to flex in an upwardly fashion when confronting obstacles which provides the operator with a greater degree of control in rough terrain.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an improvement in skis used on snowmobiles or other vehicles to facilitate forward movement and steering. More specifically, to a ski which is constructed entirely from Ultra High Molecular Weight Polyethylene (UHMW), as one piece including the attachment saddle which facilitates the attachment of a ski to the front end of a typical snowmobile. 
     Typical snowmobiles are powered by a front mounted engine attached to a rear endless track system. The track on conventional snowmobiles is suspended using springs and gas powered shocks to absorb bumps and aid in control and handling of the snowmobile. These snowmobiles are typically supplied with two skis attached to a rider operated steering system. The skis are placed in front of the track system and are, thus, the first part of the vehicle to meet obstacles such as rocks, logs and bumps. Different manufacturers have developed and utilized several different means of adding travel to each individual ski system. These systems range from a wishbone type suspension to an upright spring and dampener type system. 
     The classic, or conventional, snowmobile ski is constructed of metal and attaches to the steering system mechanism at a point near the middle of the ski. These skis are typically curved upward at the forward portion which allows the ski to ride over obstacles. The curved portion also aids the ski in traveling through snow conditions ranging from deep powder snow to slush and ice. 
     A stiff loop, made of metal rods, is typically attached to the front portion of the ski near the top of the front curved section. Some skis have used a piece of angle iron or bracketing to increase the strength of the loop. This rod or loop is then attached in a circular fashion back towards the center portion of the ski. The loops have several purposes the first of which is to strengthen the ski. The loops also act as a continuation of the curved portion of the ski and, thus, enhances the skis ability to handle bumps, moguls or obstacles. These loops have also evolved into handles to aid moving the snowmobile or picking up the front for a variety of reasons. 
     The metal ski has been standard for many years, but recently the industry has begun adopting skis made of metal bridges, reinforcements and plastic portions. This plastic may be of a type such as a Ultra High Molecular Weight Polyethylene (UHMW) or (UHMW-PE) plastic. This type of ski has been developed to overcome some of the disadvantages of the metal ski. One of these disadvantages has been that metal skis are unyielding and thus, subject to dents and bends as the ski is used in normal operation. These bends and dents eventually lead to a drop in performance of the ski and often necessitate the replacement of the ski. The use of flexible and resilient plastics has resulted in skis that are durable and able to withstand impacts that would have damaged conventional metal skis. These skis, however, are made with metal bridges, saddles or supports that result in a ski resilient at its edges, and is overall rigid. The problem with a ski that is overall rigid is that when the tip of the ski encounters a bump or obstacle the ski will follow this bump or move this results in the base of the ski losing contact with the ground or snow which substantially affects the rider&#39;s ability to control the vehicle as it will tend to dart from side to side as the ski loses contact with the ground. 
     U.S. Pat. No. 5,040,818 issued to Metheny on Aug. 20, 1991 and U.S. Pat. No. 5,145,201 issued to Metheny on Sep. 8, 1992, a continuation in part issuing from the 818 patent generally discloses one of the current plastic and metal skis. This ski has a formed plastic base with a metal bridge and saddle top. The front tip of the ski in one embodiment is equipped with a solid loop and upper bridge which holds the front of the ski in a curved and rigid form. In this embodiment the ski is substantially rigid and thus, suffers from the same handling characteristics as the metal ski in bumps. A second embodiment of this ski uses a rigid rod of adjustable length which may used to vary the upward curvature of the ski as the rod is lengthened or shortened. This embodiment has some flexibility however, the flex tends to be behind the rod&#39;s connection point and in front of the metal saddle at one point on top of the ski. This tendency to flex at one point, as the rod is solid, results in a ski that flexes too much to the point that it is damaged or broken by severe impacts such as logs or rocks, and thus, can create a dangerous situation for the rider. 
     Another ski of the plastic variety is shown in U.S. Pat. No. 5,360,220 issued to Simmons on Nov. 1, 1994. This patent discloses a ski having a plastic curved base. The base has a flexible loop attached to the underside of the front and up and over the tip of the ski to a point on the upper base of the ski near the middle. The loop is attached near the middle of the ski in a slidable fashion such that the ski may flex. This configuration works to make the ski somewhat flexible, however, as the ski is pre-curved the flex is not adjustable. The loop acts to evenly distribute the bending and flexing of the ski over a large area. Although, this works to alleviate the problems of flex in one point, and thus, prevents breakage this design is not adjustable to a given rider&#39;s size or taste. The ski operates at a preset flex within certain limits. Thus, a rider may still experience problems in bumps with darting as the ski may be too soft for a large rider and thus, flex to a point where the rear portion of the ski leaves the ground and reduces a rider&#39;s control of the sled. 
     From this discussion, it can be seen that it is desirable to supply a ski that works to absorb bumps during riding. It is also desirable to make this ski adjustable to riders of a given weight and different riding styles. Further, it is necessary that this ski be designed to flex evenly throughout its length so that the ski will not buckle under extreme bumps such as ditches, logs and rocks. 
     SUMMARY OF THE INVENTION 
     It is the primary objective of the present invention to provide a ski type steering mechanism for snowmobiles and other similar vehicles including small airplanes and BOMBARDIERS that are made up entirely of a single piece of Ultra High Molecular Weight Polyethylene (UHMW). 
     It is an additional objective of the present invention to provide such a “one piece ski” that has a flat lower surface that will tend to float on top of, rather than sinking into, snow cover regardless of whether the snow is in a packed or powder condition. 
     It is still a further objective of the present invention to provide such a “one piece ski” that has extending from the entire length of its lower surface a ninety degree which is used to provide steering and stabilizing impetus to the snowmobile to which it is attached. 
     These objectives are accomplished by the use of a flexible ski which is molded in one piece entirely of UHMW plastic. The adjustable flex ski is made up of a ski body which forms the majority of the invention and provides the base to which the other components are attached. This ski body is molded in a flat configuration. The front portion of this ski is given a pre-load function by bending the forward most portion of the ski body in an upward fashion. It is then held in this position by the use of pre-load bar which extends pivotally rearward from the tip of the ski to a ski saddle located on the upper center surface of the ski body. This saddle provides various attachment points for the pre-load bar and can thus, varies the amount of pre-load on the ski. The saddle is also supplied with an attachment point for mounting the ski on the vehicle. This configuration allows the tip of the adjustable flex ski to flex in an upwardly fashion when confronting obstacles which provides the operator with a greater degree of control in rough terrain. 
     Therefore, when the present invention encounters and impacts an obstacle, the energy created by this impact is absorbed by the flexible ski body in the pre-load area of the ski. Therefore, the impact absorbsion motion is confined to the movement of the components of the present invention and the ski body, which remains flat on the surface over which it is traveling. This ability to flex greatly enhances directional control over the prior art as the control surfaces intended to provide directional control remain in constant contact with the ground. 
     For a better understanding of the present invention reference should be made to the drawings and the description in which there are illustrated and described preferred embodiments of the present invention. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the present invention showing the manner in which its major components relate to one another to comprise the invention. 
     FIG. 2 is a top elevation view of the present invention showing the orientation of its major components in relation to the body of the ski. 
     FIG. 3 is a side elevation view of the present invention showing the orientation of its major components in relation to the body of the ski. 
     FIG. 4 is a bottom elevation view of the present invention showing the location of the 90 degree keel and the ski as configured only with the center carbide. 
     FIG. 5 is a front elevation view of the present invention showing the orientation of the 90 degree keel in relation to the body of the invention. 
     FIG. 6 is a side elevation exploded view of the front portion of the present invention showing the method of construction of the pre-load bar attachment socket. 
     FIG. 7 is a rear elevation view of the present invention showing the orientation of the 90 degree keel in relation to the body of the invention. 
     FIG. 8 is a perspective view of the saddle portion of the present invention showing the manner in which the ski attachment bolt and pre-load bar attach to the ski. 
     FIG. 9 is an exploded view of the ski saddle component of the present invention detailing the manner in which the ski mounting bolt attaches to the vertical portions of the “one piece ski.” 
     FIG. 10 is a bottom elevation view of the present invention showing it as configured with a narrow ski body which does not employ the use of the directional control veins in its lower surface. 
     FIG. 11 is a bottom elevation view of the present invention showing it as configured with a wide ski body which does allow for the use of a pair of directional control veins located in its lower surface. 
     FIG. 12 is a front elevation cut-away view of the present invention showing it as configured with an extra wide ski body allowing for the use of two pairs of directional control veins located in its lower surface. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and more specifically to FIGS. 1,  2 ,  3  and  4 , the one piece molded snowmobile ski  10  is made up of a ski body  12  which forms the majority of the invention and provides the base to which the other components are attached. The ski body  12  has ski edges  14  running laterally along the entire upper lengths and extending upwards which form a shallow depression in the center of the upper surface of the ski body  12 . At the longitudinal center of the ski body  12 , this depression is filled in and raised above the upper most surface of the ski edges  14  to form the saddle mounting platform  34 . On the upper surface of the saddle mounting platform  34  two projections called the saddle vertical mount plates  18  extend upward and form the attachment point for the ski mount bolt  26  which facilitates the attachment of the present invention to a snowmobile. 
     The ski body  12 , the saddle mounting platform  34 , and the ski saddle  16  are all formed from one piece of UHMW plastic in a manner so that the natural state of the present invention is flat along the entire length in regards to the upper surface of the ski body  12 . This one piece construction provides a lightweight ski that is extremely strong and that is less expensive to produce and sell than previous multiple piece snowmobile ski designs. 
     The pre-load function of the present invention is provided by bending the forward most portion of the ski body  12  at the pre-load zone  40 , which narrows down to a point at its front tip as in a standard ski, in an upward fashion. It is then held in this position by the use of the pre-load bar  20  which extends forward from the front of the ski saddle  16  to the tip of the ski body  12 . At is rearward end, the pre-load bar  20  is attached to the saddle vertical mount plates  18  of the ski saddle  16  by the use of the pre-load rear mount  21  which is a perpendicularly mounted cylindrical portion of the pre-load bar  20  having a hole formed longitudinally though its center. The forward most end of the pre-load bar  20  is attached to the front of the ski body  12  by the use of the pre-load bar front mount  38 . The distance between the rear and front mounts,  21  and  38 , of the pre-load bar  20  is shorter that the distance between the rear mount  21  and front mount  38  located at the tip of the ski body  12 , thus, the attachment of the pre-load bar  20  forces the ski tip to be held in an upwardly curved position. 
     The variable pre-load bar mount holes  24  located on the front portion of the saddle vertical mount plates  18  provide a means of varying the amount of pre-load placed on the ski body  12  (the use of the variable pre-load bar mount holes  24  and the ski mount bolt  26  are illustrated in FIG.  8 ). The pre-load bar  20  is pivotally attached to the ski saddle  16  by passing the pre-load rear mount bolt  22  through one of the variable pre-load mount holes  24 , through the pre-load rear mount  21  and out the opposite variable pre-load mount hole  24  where it is held in place by the use of the mount bolt nut  23 . FIG. 8 also illustrates the manner in which the ski mount bolt  26  passes through the ski mount bolt holes  25 , which contain the ski mount bolt bushings  29 , located on the saddle vertical mount plates  18  to allow for the attachment of the present invention to snowmobile. 
     The amount of pre-load placed on the ski body  12  is accomplished by changing the distance between the pre-load bar rear mount  21  and the pre-load bar front mount  38  and, therefore, the amount of pre-load placed on the tip of the ski body  12 . For example, if the pre-load bar rear mount  21  is mounted to the most forward of the variable pre-load mount holes  24 , the amount of pre-load placed on the ski body  12  is relatively small, therefore, providing a softer ride that is the recommended setting for riders of lighter weights. Conversely, if the rear of the pre-load bar rear mount  21  is mounted to the most rearward of the variable pre-load mounting holes  24 , the amount of pre-load placed on the ski body  12  is relatively large, therefore, providing a stiffer ride that is the recommended setting for riders of heavier weight. 
     These adjustments can also be made to compensate for varying types of conditions and for the type of riding to be done. Therefore, the present invention provides a means by which the handling characteristics of the skis can varied to improve the efficiency of the vehicle. This is especially important in racing where different tracks present a varying set of problems that can be overcome by simply adjusting the skis. 
     The ski saddle  16  also provides the point, through the saddle vertical mount plates  18 , at which the present invention is attached to the vehicle on which it is to be used. The mounting configuration is also detailed in FIG.  9 . This is accomplished by placing the ski cradle of a typical snowmobile between the two parallel saddle vertical mount plates  18  of the ski saddle  16  and passing the ski mount bolt  26  through the ski mount bolt hole  25  (which contains the ski mount bolt bushing  29 ) one side of the ski saddle  16 , through the ski cradle and out the other side of the ski saddle  16  where it is secured by the use of the ski mount nut  27  and washer  33 . As best illustrated in FIG. 9 of the drawings, each ski mount bolt hole  25  preferably has a first portion  60  having a first diameter and a second portion  62  having a second diameter. The second diameter of the second portion  62  is preferably larger than the first diameter of the first portion  60  of the ski mount bolt hole  25 . As further shown in FIG. 9 of the drawings, each ski mount bolt bushing  29  preferably has a first segment  70  and a second segment  72 . The first segment  70  of the ski mount bolt bushing  29  corresponds to the first portion  60  of the ski mount bolt hole  25 . The second segment  72  of the ski mount bolt bushing  29  corresponds to the second portion  62  of the ski mount bolt hole  25 . The ski mount bolt holes  25  and the ski mount bolt bushings  29  may have various cross sectional shapes including but not limited to circular and rectangular. Since the method of attaching snowmobile skis needs to be universal, the ski mount bolt bushings  29  come in a variety in inside diameters which allows the present invention to be attached to and used in conjunction with any of the many makes of snowmobiles on the market today. 
     The attachment of the pre-load bar  20  to the front tip of the ski body  12  is illustrated in FIG.  6 . The most forward portion of the upper surface of the ski body  12  is equipped with a concave depression called the mount socket  50 . The most forward lower surface of the pre-load bar  20  is equipped with a corresponding convex surface called the mount ball  48 . These two surfaces fit together and a mounting bolt is passed through the pre-load bar front mount hole  46  which is bored through corresponding locations in both the pre-load bar  20  and the ski body  12  tip. 
     The flat ski bottom  36  and the ninety degree keel features  32  of the present invention are illustrated in FIGS. 5 and 7. Both of these features run along the entire length of the ski body  12  and serve to provide the present invention with the floating action that is central to the invention. Additionally, FIG. 5 details how the pre-loading of the ski body  12  at the pre-load zone  40  creates a pre-load depression radius  41  at the front end of the ski body  12 . The depression radius  41  is a result of the design of the ski body  12  in which the upper edges of the body  12  are thicker than the center. As the ski body  12  is bent upward during pre-load, the center tends to bow slightly upward, in relation to the outside edges, which forms the depression radius  41 . This funnels snow over the 90 degree keel as the ski body  12  moves over the snow which aids in the present invention&#39;s tracking ability. 
     The general line of thinking in the design of the prior art was to build a snowmobile ski with a contoured bottom, much like the V-hull commonly employed in the design of boats. This design of ski tended to sink into the snow and it was this that provided much of the steering mechanism for the snowmobile. The flat ski bottom  36  of the present invention floats on top of the snow which creates less drag and therefore, allows the snowmobile to operate at a higher degree of efficiency. 
     The tracking and steering impetus for the snowmobile is provided by the ninety degree keel  32  which, as previously stated, runs along the entire length of the flat ski bottom  36  of the ski body  12 . The ninety degree keel  32  is an approximately a one inch square portion of the one piece snowmobile ski  10  that extends downward from the flat ski bottom  36  along its center line. When the ski body  12  is in contact with the surface of snow, the ninety degree keel  32  sinks down into the snow. Therefore, as the ski is turned by the operator, the ninety degree keel bites into the snow and directs the direction of travel of the one piece ski  10  and the snowmobile. 
     Another feature of the present invention employed to enhance its steering and tracking characteristics is the use of carbide tipped runners mounted on the flat bottom  36  surface of the ski body  12  and the lower surface of the ninety degree keel  32 . The location, method of attachment and orientation of these runners is illustrated in FIGS. 3,  4 ,  5  and  7 . Typically, the present invention would be fitted with either one or three sets of these carbide runners. The largest of these is the center carbide  44  which extends for about half of the length of the ski body and is mounted to the bottom surface of the ninety degree keel  32 . The center carbide  44  is made up of a small triangular strip of extremely hard carbide steel which is permanently attached to the bottom surface of the center carbide mount  45  which is in turn attached to the ski body  12  by the use of a plurality of attached center carbide mounting bolts  28  which extend upwards through the ski body  12  where they are held in place with series of nuts and washers. 
     The side carbides  42  and side carbide mounts  43  are similarly configured but are considerably shorter, about half that of the center carbides  44 , in length. Additionally, they are attached to the ski body  12  in much the same way as the center carbide  44  as the side carbides  42  also have mounting bolts  30  which extend up through the ski body  12  through the mount holes  31  and are held in place with a series of nuts and washers. Again, this is a very flexible design feature of the present invention as it provides a means by which the carbides can be quickly removed or installed to compensate for varying conditions encountered by the user. It also enables a person to comply with the rules of certain racing sanctioning bodies as many of these do not allow the use of one or more of these carbides. 
     FIGS. 10,  11  and  12  illustrate the variety of widths that the ski body  12  of the present invention comes in and the use of the optional directional control veins  39 . FIG. 10 shows a narrow ski body  12  in a width of approximately five inches which may be too narrow to allow for the use of the directional control veins but still allows for the use of side carbides  43  when conditions and regulations allow for it. FIG. 11 shows the ski body  12  in a wider width which allows for the use of a pair of control veins  39  (angled depressions in the lower surface of the ski body  12 ) which aid in directional impetus for the present invention. 
     FIG. 12 illustrates the ski body  12  in a still wider width which allows for the use of two pairs of the control veins  39 . This figure also further details the configuration and manner of construction of the control veins  39 . The outer edges of these control veins  39  are cut at an inward angle although the vein itself is typically a right angle section. It has been found that the inward angle seems to work best to form 10 degrees to 25 degrees. The purpose of this angle is that when the skis of a snowmobile are turned to effectuate a turn, they tend to rotate slightly in the horizontal plane in the direction of the turn. Thus, when the skies are fully turned the angle of the outer edge of the control veins  39  forms a ninety degree angle in relation to the surface of the snow which adds a greater degree of control to the turning snowmobile. 
     Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. It should also be stated at this point that although this invention is described in the context of a snowmobile, this invention would be equally useful on airplane skis, BOMBARDIERS, SNO-SCOOTS, and other similar vehicles. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.