Abstract:
A skateboard comprising a rigid elongated board having front and rear portions, and front and rear wheel trucks mounted to the underside of the board. The wheel trucks each have multiple wheels mounted in-line. A steering platform is at the front of the board for use by the rider to steer the board. The steering platform is rotatable and is connected by a linkage system to the wheel trucks wherein, by rotating the steering platform, each wheel within their respective truck is equally angularly displaced to effect a turning movement of the board.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the field of skateboards, and more particularly to an improved skateboard which comprises two or more sets of in-line wheel trucks wherein two or more wheel trucks may be steered by the foot of the rider regardless of any shifts in the weight of the rider. 
     2. Description of the Related Art 
     The prior art is replete with patents dealing with skateboards. Typically, skateboards come with wheel trucks having axial alignment for multiple wheels on the trucks or may have in-line wheel trucks similar to the type used in the present invention. The typical conventional skateboard comprises a rigid elongated board having front and rear portions with a wheel truck assembly fixedly mounted below the front portion of the board and a rear wheel truck assembly fixedly mounted beneath the rear portion of the board. Normally, steering is accomplished by a complex redistribution of the weight of the rider standing on the board. Obviously, learning to redistribute the weight as required to steer a skateboard in a safe manner is a time consuming and dangerous process. 
     Some of the prior art disclose skateboards which have axially aligned wheels and, to assist the rider in steering the board, the wheels are tapered from side to side to effectively increase the turning ability of the board when the board is tilted to one side or the other to effect a sharper turning radius. However, such boards do not have the capability of individually steered wheel trucks, thereby limiting the amount of steerability of the board. 
     Other patents in the prior art are known to have steerable wheel trucks. For instance, in the patent to Piazza, Jr. (U.S. Pat. No. 4,202,559) a steerable skateboard is shown wherein a steering platform is placed at the front of the board for effecting steering by the user, but only the front trucks is steerable. There is no linkage to the rear truck. The board of the Piazza patent utilizes aligned wheel trucks and obviously only the front wheel truck is steerable. 
     In the Welsh Patent (U.S. Pat. No. 5,236,208) another type of skateboard is shown wherein the board may be steerable both from the front and the rear, and the user will have steering capability by using both feet. Again, there is no linkage between the front and rear trucks and the effective steering must be by both feet. This patent also discloses wheel trucks which have axially aligned wheels and not in-line wheel trucks. 
     In the Yi Patent (U.S. Pat. No. 5,660,401) an in-line skateboard is shown having turning capability. However, the rollers are only pivotally mounted for steerability and the steering is effected in response to pressure placed upon the wheel trucks by the user. There is no independent steering of the wheel trucks from the foot of the user. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention and the contemplated problems which have and continue to exist in this field, the objectives of this invention are to provide a new and improved steerable in-line skateboard. The board has, at its front, a circular steering platform onto which one foot of the user is placed and then, by turning the platform with the foot, the person steering is able to effect angular displacement of all of the wheels of both the front wheel truck and the rear wheel truck to effect a rapid and decisive turning maneuver. When the platform is rotated and the front wheels of the front truck are turned, a steerage linkage mechanism cooperatively is attached to the wheels of the rear truck and will also effect an angular displacement of the rear wheels to greatly enhance the turning of the board. 
     Each wheel of each truck is individually mounted upon an axle wherein each axle is angularly displaced upon the rotation of the platform by the rider. To effect a rapid turning motion, the wheels of the rear truck are angularly displaced in a direction opposite from the angular displacement direction of the wheels of the front truck. 
     Further, since each wheel axle is angularly displaceable, a system is incorporated to the “at-rest” position of the axles and to provide to the skateboard a datum position which will provide a straight travel path unless the rider rotates the platform to effect the turning maneuver. 
     Other objects, advantages and capabilities of the invention will become apparent from the following description taken in conjunction with the accompanying drawings showing the preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of the skateboard of the present invention; 
     FIG. 2 is a left side elevation view; 
     FIG. 3 is a bottom plan view; 
     FIG. 4 is a partial perspective view of a wheel assembly mounted in the arcuate axle slot with details of the linkage attaching to the wheel assembly; 
     FIG. 5 is a bottom plan view showing the wheels effecting a turning maneuver; 
     FIG. 6 is a partial bottom plan sectional view of a portion of the bearing of the wheel assembly; 
     FIG. 7 is a bottom plan view of a second embodiment of the steering linkage of the present invention; and 
     FIG. 8 is a side elevation vie of the embodiment of FIG.  7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For a fuller understanding of the nature and desired objects of this invention, reference should be made to the following detailed description taken in connection with the accompanying drawings. Referring to the drawings wherein like reference numerals designate corresponding parts throughout the several figures, reference is made first to FIGS. 1 and 2. The skateboard  11  comprises a rigid elongated board member  12  having a tapered front portion  13  and a rounded blunt rear portion  14 . Near the tapered front portion  13 , lying within the top of the board  15  is a circular steering platform  16  which is mounted by steering pivot  17  in order for is the platform  16  to be rotatably movable by a selected foot of a rider of the board. While in the preferred embodiment, the steering platform  16  is shown at the front portion of the board  15 , it may be that some riders may prefer it to be mounted at the rear and such a configuration is contemplated herein. To give the rider a sense of feel as to the position of the rear portion  14  of the board, it is contemplated that the rear portion will be upwardly flared in an area shown by numeral  18  which will allow the user a definite sense of feel of where the end of the board is at any one time. 
     Upon the flat bottom board surface  19  are mounted a front wheel truck  21  and rear wheel truck  22 . The wheel trucks are mounted within a generally U-shaped frame  23  which is a suitably fixedly attached to the bottom surface  19  of the board  12 . The frame  23  has a middle portion  24 , which is attached to the bottom surface  19 , and depending downwardly from each edge of the middle portion of the frame  24  are depending frame flanges  25  and  26  respectively. The frame  23  is generally constructed so that a proximal end  27  lies near the front portion  13  of the board and a distal portion of the frame  28  lies near the rear portion  14  of the board. 
     Placed near the proximal end  27  of the frame  23 , and mounted to the frame flange  26 , is a bearing support plate  29  having an elongated configuration so constructed that it will house the bearing structure of the individual wheels. A similar bearing support plate  31  is mounted to depending frame flange  25  near the distal end  28  of the frame. 
     Mounted to depending frame flange  25  near the proximal end of the frame  27  is an elongated front truck axle plate  32  which also is designed to cooperate with the axle assembly of the individual wheels of the front truck  21 . Similarly, at the distal end  28  of the frame, in conjunction with the wheels of the rear truck  22 , is a rear truck axle plate  33  which is mounted to depending frame flange  26 . 
     Turning now to the individual wheel trucks  21  and  22 , it can be seen that each truck has three wheels  34 . While the contemplated embodiment utilizes three wheels in each truck, it should be noted that this would be a matter of design and possibly economy. However, each truck could have more or less wheels as desired and such is contemplated within this invention. As has been previously noted, the wheels  34  of each truck are mounted in-line as shown. Each wheel  34  is mounted upon an axle  35  and each axle is mounted within the frame  23 . With respect to front truck  21 , the axles  35  have one end fixedly mounted within a spherical ball bearing  36  which is, in turn, mounted within the bearing support plate  29 . The other end of each wheel axle  35  in the front truck is then mounted within an arcuate axle slot  37  within the front truck axle plate  32 . The steerage end  38  of each axle  35 , being mounted within the arcuate axle slot  37 , is capable of a complete range of motion fore and aft within the axle slot upon application of a moving force to the steerage end  38  of the axle. When the wheels  34  of each wheel truck are in complete longitudinal alignment for straight movement of the skateboard  11 , each axle will be resting at the top center position  39  of the arcuate axle slot. The rear truck  22  has a similar arrangement, however, the positions of the parts are reversed with respect to the depending frame flanges. In the rear truck  22 , the axle  35  terminates in the spherical ball bearing  36  which is mounted in the bearing support plate  31 . The steerage end  38  of the axle  35  is positioned within the arcuate axle slot  37  of the axle plate  33 . These differences of location within the depending frame flanges will become apparent from the later description of the operation of the invention. 
     In order to effectively steer wheel trucks  21  and  22 , a steering mechanism  41  is shown in FIG.  3 . The input to the steering mechanism is from the steering platform  16  which has a crank mount  43  fastened to the underside  42  of the platform to which is attached a steering linkage  44 . The steering linkage connects the crank mount  43  with a front truck wheel linkage arm  45  by fastening the steering linkage  44  with a pivot  46  to the crank mount  43  at the proximal end of the linkage  44 , and at the distal end of the linkage  44  by a fastener  47 . The front truck wheel linkage arm  45  is in turn connected to the rear truck wheel linkage arm  48  by a linkage plate  49  which connects the distal end of the linkage arm  45  to the proximal end of linkage arm  48 . 
     The front truck wheel linkage arm  45  is in turn connected to each axle support member  51  by linkage pin  52 . With the linkage just described, it is evident that all wheels of the front truck  21  and all wheels of the rear truck  22  will turn in tandem by the same degree of angularity when the platform  16  is rotated. As platform  16  is rotated, the crank mount  43  is moved forwardly or rearwardly, as the case may be, thereby moving the steerage linkage  44  in the same direction which will move the linkage arm  45  and the truck linkage plate  49 , and ultimately will move the rear truck wheel linkage arm  48 . These movements will effect an angular displacement of the wheels of the respective trucks in a manner shown in FIG.  5 . 
     Referring now to FIG. 5, it can be seen that if the platform  16  is rotated clockwise (when viewing the underside of the skateboard  11 ) the entire steering mechanism  41  is moved toward the rear portion  14  of the skateboard and this effectively angularly displaces wheels  34  of the front truck  21  by moving the respective axles  35  in a manner which will turn the wheels in the direction indicated in FIG.  5 . Concurrently therewith, the rear truck axle plate  33  will move the axles  35  of the wheels  34  of the rear truck  22  in the manner shown. By such a movement, the skateboard will make an effective sharp turn in the direction indicated by the angular displacement of the wheels of the front truck  21 . 
     FIGS. 7 and 8 show a modification of the steering mechanism  41  as disclosed in FIG.  3 . The modified steering mechanism is indicated by the numeral  53 . The steering mechanism of FIGS. 7 and 8 allow the rider to adjust the effective turning rate of the front and rear wheel trucks  21  and  22  respectively. The modified steering mechanism comprises a crank mount  54  mounted to the underside  42  of the platform  16 . The crank mount is of generally rectangular configuration and would be supplied with a plurality of apertures  55  to which a forward steering linkage  56  and a rear steering linkage  57  would be suitably attached by fasteners  58  at the proximal ends of the respective steering linkages. The distal ends of the respective steering linkages would be suitably connected by linkage pins  52  and fixed for rotatable motion adjacent to the respective truck wheel linkage arms  45  and  48 . The invention of the modified version would operate essentially the same as the originally disclosed version in that the turning of steering platform  16  would move the crank mount forwardly or rearwardly thereby allowing the steering linkages  56  and  57  to operate upon the wheel linkage arms  45  and  48  to angularly displace the wheels of the respective front and rear trucks  21  and  22  in a manner shown in FIG.  5 . While the operation of the steering mechanism in the embodiments of FIGS. 7 and 8 work very similarly to that in the earlier figures, the addition of adjustable steering linkages  56  and  57  allow the user to adjust the turning rate of the wheels of the individual trucks for a more precise steering ratio in accordance with the desires of the rider. 
     Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, various modifications may be made of the invention without departing from the scope thereof and it is desired, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and which are set forth in the appended claims.