1. Field of the Invention
The present invention relates in general to recreation equipment and more particularly to a platform equipped with skate-type wheel units with a laterally compliant sliding surface (crosswise to the longitudinal axis of the platform) approximating the lateral compliance experienced in some forms of snow skiing and water skiing.
2. Description of the Prior Art
Proposals have been made heretofore for recreational equipment enabling enjoyment of such sports on dry land surfaces. These proposals in general provide rider supporting structures mounted on rollers for use on inclined surfaces. Dry land skiing apparatus is representative. The closest known prior art heretofore proposed is disclosed in: McDonald U.S. Pat. No. 4,134,600, Schinke U.S. Pat. No. 3,399,904, Boyden U.S. Pat. No. 3,023,022, McDonald U.S. Pat. No. 3,684,305. Each of these prior constructions and others of a more remote construction fail to provide the rider with an independent lateral degree of freedom upon a rigid platform construction.
An independent lateral degree of freedom requires that the extent of lateral motion on a rigid platform fitted with a wheeled steering mechanism be adjustable and independent of the arc of curvature of the steering mechanism in a turn, and that lateral shifting occurs with both of the rider's feet. This is in contrast to the above-identified prior art which do not provide such action. This lateral motion (crosswise to the platform's longitudinal axis) referred to above is analogous to slalom skiing where the skier's speed is limited by lateral slipping relative to the longitudinal axis of the skis as tight turns are negotiated.
An additional feature of this invention is the provision of wheels mounted on each end of a flexible structure extending laterally from the platform. These wheels and the flexible structure to which they are attached provide tilt resistance as the rider shifts his or her weight to an off-center position, controls the arc of curvature obtainable with the steering mechanism (skate type wheel units), and provides rolling resistance by means of a frictional type braking system on the wheels, thus allowing the rider to control speed on inclined surfaces.
McDonald U.S. Pat. No. 4,134,600 discloses external rollers which are used to limit impact of the riding structure with the ground. However, the wheels are not in contact with the ground except in extreme turns and are not meant to be used to limit forward speed. In addition, the roller-biased angular position illustrated in this reference is associated with a turn direction which is opposite to the currently proposed invention.
Schinke U.S. Pat. No. 3,399,904 utilizes lateral positioned rollers as a tilt restraint which are intimately part of the turning mechanism. In contrast, the lateral wheels supported on the flexible structure of the present invention are not used as a turning mechanism, but are used only for support as the rider slides laterally and for braking resistance in turns.