Abstract:
A two-wheeled roller skate with canted wheels has an axle for the forward wheel located well forward of the ball of the foot. The axle for the rear wheel is located at the rear of the skater&#39;s heel. The wheels are canted so that the front and rear wheels contact the ground on the opposite sides of the center line of the skater&#39;s foot. In plan projection, the axles are preferably non-parallel in order to provide steering correction. The amount of steering correction desirable will depend on the skater&#39;s skill and the nature of the skating activity. In alternative embodiments, the present invention incorporates novel braking mechanisms.

Description:
This is a continuation of co-pending application Ser. No. 08/901,118, filed Jul. 28, 1997, now U.S. Pat. No. 5,951,028. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of roller skates and, particularly, to an improved skate with canted, large diameter wheels. 
     2. Prior Art 
     Various designs of roller skates have been developed over the years. At the present time, “in-line” skates are particularly popular. This type of skate has a plurality of small-diameter wheels aligned in a longitudinal direction beneath the sole of the skater&#39;s foot. A number of advantages are claimed for this design of a skate. However, the small diameter of the wheels inherently limits the speed that can be achieved and limits the use of the skates to relatively smooth surfaces. 
     Among alternative skate designs, skates with large-diameter wheels have been proposed for over a century. For example, U.S. Pat. No. 89,833 discloses a skate with a single wheel of large diameter for use in skating on fields and other uneven surfaces. This skate, and many similar prior art designs, places the wheel to the outside of the skater&#39;s foot. While this allows a lower center of gravity than if the wheel were to be located entirely below the skater&#39;s foot, undue strain is placed on the skater&#39;s ankles because of the lateral offset between the center line of the skater&#39;s foot and the point of contact between the wheel and the ground. One solution to this problem is to mount the wheel at an angle with respect to vertical so that the point of contact with the ground will be directly below the skater&#39;s foot. Such a design for a single-wheeled skate is shown, for example, in U.S. Pat. No. 2,931,012. 
     Single-wheeled skates are, of course, inherently unstable. A design for a skate with two large diameter wheels is shown in U.S. Pat. No. 3,885,804 to Cudmore. In this design, two large, canted, equal-sized wheels are mounted con axles extending outwardly from a rigid sole-plate. As disclosed by Cudmore, the canted wheels contact the ground directly beneath the center line of the sole-plate. The wheels are dished with their concave sides facing toward the sole-plate so that a portion of the sole-plate extends into the wheel concavities to permit the sole-plate to be positioned very close to the ground. Cudmore&#39;s design provides a reasonably stable skate in comparison to many of the prior art designs; however, development of the present invention has yielded improved stability and responsiveness over the design of Cudmore. Furthermore, the dished wheels used by Cudmore to achieve a low center of gravity inherently limit the ability to turn sharply since the outside surfaces of the wheels will contact the ground when the skate leans in a sharp turn. The present invention overcomes this disadvantage by positioning the wheels so that dishing is not necessary to achieve an acceptably low center of gravity. 
     SUMMARY OF THE INVENTION 
     The present invention is a two-wheeled roller skate with canted wheels. In a preferred embodiment, the axle for the forward wheel is located well forward of the ball of the foot, approximately in line with the skater&#39;s toes. The axle for the rear wheel is located at the rear of the skater&#39;s heel. The wheels are canted so that the front wheel contacts the ground slightly outside of the center line of the skater&#39;s foot and the rear wheel contacts the ground slightly inside of the center line. This contact geometry permits the use of a relatively small diameter front wheel and thereby allows the sole of the skate to be positioned close to the ground. In plan projection, the axles are preferably non-parallel in order to provide steering correction. The amount of steering correction desirable will depend on the skater&#39;s skill and the nature of the skating activity. In alternative embodiments, the present invention incorporates novel braking mechanisms. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the roller skate constructed in accordance with the present invention. 
     FIG. 2 is a side elevational view of the roller skate of FIG.  1 . 
     FIG. 3 is a partial bottom plan view of the roller skate of FIG.  1 . 
     FIG. 4 is a partial front elevational view of the roller skate of FIG.  1 . 
     FIG. 5 is a partial rear elevation view of the roller skate of FIG.  1 . 
     FIG. 6 is a partial side elevation view of an alternative embodiment of the present invention illustrating a braking mechanism. 
     FIG. 7 is a cross-sectional view taken along line  7 — 7  of FIG.  6 . 
     FIG. 8 is a perspective view of an other alternative embodiment of the present invention. 
     FIG. 9 is a partial side elevational view of the roller skate of FIG.  8 . 
     FIG. 10 is a side elevational view of yet another alternative embodiment of the present invention. 
     FIG. 11 is a side elevational view of still another alternative embodiment of the present invention. 
     FIG. 12 is a side elevational view of a further alternative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods and devices are omitted so as to not obscure the description of the present invention with unnecessary detail. 
     FIG. 1 is a perspective view of a skate  10  constructed in accordance with the present invention. Skate  10  comprises a boot  12  to which are attached a front wheel  14  and a rear wheel  16 . The front wheel  14  carries tire  15  and rear wheel  16  carries tire  17 . In a preferred embodiment, the outside diameter of front tire  15  is about five inches and that of rear tire  17  is about seven inches. The invention is not limited in this regard and other sized or equal-sized wheels/tires may be used. In some embodiments, such as illustrated in FIG. 12, the front wheel/tire may have a larger diameter than the rear. 
     Skate  10  is intended for the right foot of the skater, thus wheels  14  and  16  are mounted to the outside of boot  12 . It is to be understood that a corresponding skate is also provided for the left foot of the skater, which is generally a mirror image of skate  10 . As will be more apparent in the discussion that follows, wheels  14  and  16  are canted so that tires  15  and  17  contact the ground directly beneath boot  12  rather than to the outside thereof. 
     Boot  12  is generally constructed in the same manner as boots used with. conventional in-line skates. Accordingly, details of boot  12  will not be discussed herein. Wheels  14  and  16  may be machined or cast using a suitable metal or plastic material. Tires  15  and  17  may be made of a natural or synthetic rubber material and may be solid, foam-filled or pneumatic. Tires  15  and  17  may also be made of urethane plastic as has become standard practice for in-line skate wheels. 
     FIG. 2 is an inside elevation view of skate  10 . A sole plate or chassis  18  is attached to the bottom of boot  12  to provide structural support for wheels  14  and  16 . Alternatively, boot  12  and chassis  18  could be an integral structure. The axle supporting front wheel  14  is located well forward of the ball of the skater&#39;s foot, either ahead of or in line with the skater&#39;s toes. The axle supporting rear wheel  16  is located generally below the skater&#39;s heel. 
     Referring now to FIG. 3, chassis  18  is shown in bottom plan view. When projected in plan view, the axles of wheels  14  and  16  are generally perpendicular to the center line of the skate. It has been found, however, that superior skating performance is achieved with slight “toe-in” of the front wheel and/or “toe-out” of the rear wheel as indicated by the arrows in FIG.  3 . This provides a desirable steering correction to counteract the tendency of the skate. to steer outwardly due to the offset geometiy of the wheel-to-ground contact patches as described below. It has been determined that neutral handling (i.e., the situation where the skate tracks straight ahead while coasting) is best achieved with the rear wheel parallel to the skate center line and the front wheel toed in at about 2°. 
     For more experienced skaters, who desire power plus control and greater. hill-climbing ability, a larger toe-in angle up to about 3° or 4° is preferred at the front wheel. This causes the left skate to steer slightly to the right and the right skate to steer slightly to the left and allows the skater to cover a greater distance with each push-off. The optimum configuration for all-around skating has been found to be a toe-out angle at the rear wheel of about 1-1.5° and an equal amount of toe-in angle at the front wheel. 
     Each skater, depending upon experience and the nature of the terrain to be traversed, may prefer a slightly different adjustment of wheel angles. Indeed, the desirable range of wheel angles extends from 0° to about 5°. Therefore, it may be useful to provide a manual adjustment for toe-in of the front wheel and/or toe-out of the rear wheel within this range. 
     FIGS. 4 and 5 are front and rear elevational views, respectively, of skate  10 . Projected in this plane, it can be seen that the axles of the front and rear wheels are substantially parallel. It is important to observe that front tire  15  contacts the ground to the outside of the center line of the skate, whereas rear tire  17  contacts the ground to the inside of the center line of the skate . The lateral offset of the front and rear contact patches is approximately equal at about ½ inch from the center line. In an alternative embodiment, such as that shown in FIG. 12, the front contact patch may be inside of the center line and the rear contact patch to the outside of the center line. This would be the case particularly when the front wheel has a larger diameter than the rear. 
     In an alternative embodiment, such as that shown in FIG. 12 where the front wheel has a larger diameter than the rear wheel, the front contact patch may be inside of the center line and the rear contact patch to the outside of the center line (the opposite relationship to that shown in FIGS. 3-5) axis of the skate. Referring back to FIG. 3, it can be seen that the roll axis is angled outwardly from the longitudinal center line of the skate. This geometry contributes to the stability of the skate at rest by distributing the skater&#39;s weight laterally with respect to the center line. 
     FIGS. 6 and 7 illustrate an optional braking mechanism for use with the present invention. Skate  30  includes rear wheel  32  and rear tire  33 . Wheel  32  includes an annular braking surface  34 . A lever  36  is pivotally connected to chassis  38  at pivot  40 . A relatively small diameter wheel  42  is mounted at the rear end of lever  36  and contacts the ground surface traversed by skate  30 . Alternatively, the rear end of lever  36  may have a simple skid for contacting the ground instead of wheel  42 . 
     The forward end of lever  36  operatively engages brake lever  44 , which is pivotally coupled to chassis  38  at pivot  46 . Brake shoe  48  is rigidly attached to brake lever  44  with rivets or other suitable fasteners. Brake lever  44  is biased away from braking surface  34  by means of spring  50 . To engage the brake while skating, the skater simply rotates the skate on which braking is desired about the axis of the rear wheel by shifting the skater&#39;s body weight. This causes lever  36  to rotate on pivot  40  and bear down on brake lever  44 . This, in turn, urges brake shoe  48  into contact with braking surface  34 . The amount of braking force applied is directly related to the amount by which skate  30  is rotated about the axis of rear wheel  32 . It should be noted that this braking mechanism also has a beneficial stabilizing effect on skate  30  since it inherently limits the amount by which the skate can rotate about the axis of the rear wheel and thus helps prevent the skater from falling backwards. 
     The braking system shown in FIGS. 6 and 7 is not ideally suited to use on uneven terrain. An alternative braking system is illustrated in FIG.  8 . Here, brake actuation is effected by a pair of hand grips  60  coupled to respective skates  62 . Each of hand grips  60  communicates with its respective skate by means of cable  64 , which may be like a conventional bicycle brake cable for mechanical actuation of the brake. Alternatively, hand grips  60  may incorporate a hydraulic reservoir, in which case, hydraulic pressure is communicated through cable  64  to a hydraulic slave cylinder in skate  62 . 
     FIG. 9 illustrates a hydraulic braking mechanism for skate  62 . Hydraulic cable  64  communicates with brake caliper  66 , which is rigidly mounted to chassis  68 . Brake shoes (not shown) within caliper  66  exert a clamping force on brake disc  70  in a manner similar in operation to automotive disc brakes. 
     FIG. 10 illustrates an alternative embodiment of the present invention. Skate  80  has a front wheel  82  similar to that of the previously discussed embodiments. However, rear wheel  84  is substantially larger in diameter, which is desirable for speed skating. In the illustrated embodiment, rear wheel  84  has a diameter of approximately 10 inches. To accommodate a wheel of this size, the axle is located behind the skater&#39;s heel, thereby obviating the need to elevate the skater&#39;s foot higher above the ground. 
     FIG. 11 illustrates a further embodiment of the present invention that is a variation of the embodiment shown in FIG.  10 . Skate  90  has a large diameter rear wheel  94  as in the previously discussed embodiment. In this embodiment, however, front wheel  92  is located forward of the skater&#39;s toe, which is desirable for high speed skating. Front wheel  92  may have a fixed location on skate  90  or a manual adjustment may be provided so that the skater can locate the axle of the front wheel longitudinally at a desired position within a range of adjustment. 
     It will be recognized that the above described invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the disclosure. Thus, it is understood that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.