Heretofore, skateboards have been well known for many years and have constantly gained popularity for amusement and recreational purposes as well as for competitive purposes, as a sports activity. As known, a skateboard generally has a rigid baseboard upon which the user is capable of standing, and the bottom of the board is provided with two pair of rollers, front and rear, which are typically about 21/2 inches in diameter with the wheels being made of various polymeric or rubber compositions. The wheels are connected by an axle (sometimes called trucks) and are supported by bearings on the axle. Typically, the axle is rigidly mounted by a swing-arm structure which enables axial displacement of the axle in response to a leaning motion of the user which provides the steering feature for the skateboard. As known, the user stands on the board and pushes his foot against the ground to accelerate the board. Accordingly, the speed developed by the skateboard is directly proportional to the agility and strength of the user and hence, it is advantageous to provide a skateboard wherein its speed can be increased and/or prolonged without being solely dependent upon the physical endurance and/or strength characteristics of the user.
One prior type of hand-manipulation for a skateboard is disclosed in U.S. Pat. No. 4,319,760 granted Mar. 16, 1982 wherein the skateboard was provided with a uni-directional, slip-clutch transmission in association with a drive chain for driving a sprocket wheel that was attached to the axle (truck) of the board. In another application, there is disclosed in U.S. Pat. No. 4,807,896 issued Feb. 28, 1989 an external power mechanism for a skateboard which required the use of two oppositely threaded spools. The spools were spirally threaded and coupled to the axle (truck) to give additional rotational force to the wheels by a pull cable. The speed is based on the predetermined length of the cable in relation to the diameter of the cable spools.