Patent Publication Number: US-6338494-B1

Title: Articulated two wheel board

Description:
FIELD OF THE INVENTION 
     The present invention relates to board based recreational devices like skateboards and mountain boards. 
     BACKGROUND OF THE INVENTION 
     There are many types of board based recreational devices. These include skateboards with four wheels for operation on pavement; mountain boards with four wheels for operation on rough terrain and inline skateboards for operation on pavement. 
     The prior art includes a plurality of mountain boards with four wheels that extend above the level of the board. For example, U.S. Pat. No. 5,794,955 describes such a four wheel mountain board. 
     The prior art includes U.S. Pat. No. 5,160,155 which discloses a skateboard having two wheels in tandem. This patent also discloses a spring based mechanism for dampening and centering the front steering wheel. The front steering wheel is positioned rear of the point of pivot between the wheel and the skateboard. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an articulated two wheel board device for operation on rough and smooth terrain. 
     It is a more particular object of the invention to provide a board that is made up of two sections, the front board member and the rear board member. 
     It is another object of the invention to provide a pivot point where the front board member connects to the rear board member. 
     It is another object of the invention to provide a rear wheel that extends behind the rear board member and above the level of the rear board member and attached to the rear board member. It is another object of the present invention to provide a front wheel that extends in front of the front board member and above the level of the front board member and attached to the front board member. 
     Preferably the front wheel is connected to the front board member by means of a front fork member which attaches to the front wheel axle. 
     Preferably the rear wheel is connected to the rear board member at the rear pivot point by means of a rear fork which attaches to the rear wheel axle. 
     It is another object of the invention to provide the pivot point which includes thrust bearings, thrust bearing races, a pivot bolt and a pivot nut. 
     In some embodiments there is a flexible rod that runs under the board members along the long axis the length of both board members and is attached at one end to the rear fork member and the other end at the front fork member 
     In some embodiments the board member is constructed of 13 ply birch which gives it great stiffness and can support the pivot point. 
     In some embodiments the board member is constructed of different material. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     These and other aspects of the present invention will become more evident upon reading the following description of the preferred embodiment in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a prior art side view of a skateboard. 
     FIG. 2 shows the skateboard of FIG. 1 as seen from the underside. 
     FIG. 3 is a prior art side view of a mountain board. 
     FIG. 4 shows the mountain board of FIG. 3 as seen from the underside. 
     FIG. 5 is a prior art view of a skateboard having two wheels in tandem. 
     FIG. 6 shows the skateboard of FIG. 5 as seen from the underside. 
     FIG. 7 is a side view of the present invention. 
     FIG. 8 shows the present invention of FIG. 7 as seen from the underside. 
     FIG. 9 shows the present invention of FIG. 7 as seen from the top. 
     FIG. 10 is a side view of a portion of the present invention which details the pivot point. 
     FIG. 11 is a side view of a user riding the current invention during the power stroke where the user obtains forward motion from contact of the user&#39;s foot and the ground. 
     FIG. 12 is a side view of a user riding the current invention while coasting where the user&#39;s feet are positioned perpendicular to the long axis of the invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG.  1  and FIG. 2 illustrates a prior art skateboard device  10 . In FIG.  1  and FIG. 2 the board member  11  is supported from below by four wheels  12 ,  14 ,  20  and  22 . Wheels  12  and  20  are connected together by axle  24 . Wheels  14  and  22  are connected together by axle  26 . Axle  24  is connected to the board  11  by truck  16 . Axle  26  is connected to the board  11  by truck  18 . 
     FIG.  3  and FIG. 4 illustrates a prior art mountain board device  28 . In FIG.  3  and FIG. 4 the board member  29  is supported from below by four wheels  30 ,  32 ,  34  and  36 . Wheels  30  and  34  are connected together by axle  38 . Wheels  32  and  36  are connected together by axle  40 . Axle  38  is connected to the board  29  by truck  42 . Axle  40  is connected to the board  29  by truck  44 . 
     FIG.  5  and FIG. 6 illustrates a prior art skateboard device  46 . In FIG.  5  and FIG. 6 the board member  47  is supported by a rear wheels  48  and a front wheel  50 . Rear wheels  48  extends through the board member  47  through opening  53  and is attached to the board member  47  at axle  52 . The front wheel  50  is connected to the board  47  by fork  54  connected at pivot  56  which is forward of front wheel  50 . Pivot  56  allows fork  54  and wheel  50  to move perpendicular to the axis through pivot  56 . Wheel  50  is centered with axis perpendicular to the long axis of the board  47  by spring  58  which connects at one end to the rear of fork  54  and at the other end to board  47  at attachment point  60 . A user riding this board can affect a change of direction by shifting his/her weight on the board. Under weight shifting conditions the fork  54  and front wheel  50  moves perpendicular to the axis at pivot  56 . This motion is much like a caster on a shopping cart. The spring  56  dampens and governs the motion. When the user&#39;s weight is more directly centered along the long axis of board  47 , the axis of wheel  50  will return to a position perpendicular to the long axis of board  47 . 
     FIG. 7, FIG.  8  and FIG. 9 illustrates the current invention  68 . In FIG. 7, FIG.  8  and FIG. 9 the rear board member  69  is supported from the ground by wheel  72 . The rear wheel  72  extends to the rear of board member  69  and extends above the level of board member  69 . The front board member  70  is supported from the ground by wheel  74 . The front wheel  74  extends to the front of board member  70  and extends above the level of board member  70 . 
     The rear board member  69  is attached to the front board member  70  at pivot point  84 . The front wheel  74  is attached to fork member  78  at connection points  75  and  77  and extends under the front of board member  70  and connects with board member  70  at  82 . The rear wheel  72  is attached to fork member  76  at connection points  73  and  89  and extends under the rear of board member  69  and connects with board member  69  at  80 . 
     A flexible member  86  connects the rear of front fork  76  a with the front of rear fork  78 . 
     The user places one foot on rear board member  69  with that foot oriented about  45  degrees relative to the major axis of the device and is propelled forward by the user pushing against the ground with his/her other foot. This motion is much like the typical means of propelling a skateboard forward. The flexible member  86  gives the invention a false center which keeps the major axes of each board member in alignment even when the user&#39;s foot is not on either board member. 
     Once the user has achieved a satisfactory rate of speed from this means, the user can place the other foot on the front board member  70  orienting each foot in a direction perpendicular to the long axis of the device. With both feet oriented perpendicular to the major axis of both board members  69  and  70 , the user has more control over the invention and can affect a change in direction by moving the front and rear board member around the pivot point  84  with the user&#39;s feet. The user&#39;s weight and feet motion can overcome the centering force of the flexible member  86 . 
     FIG. 10 is a side view of a portion of the present invention which details the pivot point. In FIG. 10 the pivot bolt  100  extends through front board member  94  and rear board member  98  and is visible as  102 . A heavy gauge washer  104  spreads the load of pivot bolt  100 . Pivot bolt  100  also passes through thrust bearing  106 , top thrust bearing race  108  and bottom thrust bearing race  110 . Pivot bolt  100  also passes through thrust bearing  112 , top thrust bearing race  114  and bottom thrust bearing race  116 . Pivot bolt  100  is secured against bottom thrust bearing race  116  by nut  118 . When pivot bolt  100  is secured by nut  118 , rear board member  98  and front board member  94  are free to rotate around pivot bolt  100 . Industrial strength thrust bearings and bearing races allow rear board member  98  and front board member  94  to rotate around pivot bolt  100  irrespective of the downward pressure of the user standing on the device. 
     FIG.  11  and FIG. 12 are descriptions of the current invention  134  being ridden by user  138 . 
     In FIG. 11 the user  138  is in the power stroke where the user is obtaining forward motion by moving his/her right foot  140  against the ground  142 . The user&#39;s left foot  144  rests on the rear board member  136 . While this description describes the user&#39;s left foot remaining on the board while driving off the ground with the user&#39;s right foot; the opposite arrangement is also possible. 
     In FIG. 12 the user has gained sufficient forward motion and is now coasting. The user  138  has repositioned his/her feet  140  and  144  to a position pointing perpendicular to the long axis of the invention  134 . The user&#39;s left foot  140  is on the rear board member  136  and the user&#39;s right foot  144  is on the front board member  146 . The user  138  can now affect direction changes of the invention  134  by changing the orientation of his/her feet relative to each other without lifting either foot off the invention. Moving the user&#39;s feet inward with his/her toes being closer than his/her heels causes the device to move to the left. Moving the user&#39;s feet outward with his/her toes being farther apart than his/her heels causes the device to move to the right.