A traditional skateboard fundamentally consists of a board, normally made of wood to which four wheels in pairs are fixed, which serves for practicing the sport called skateboarding. The wheels are grouped in two units of two wheels, the axis of each one being held with a flexible rod slightly inclined in relation to the board which allows it to carry out turns by inclining the board from one side to another and the smooth turning movement of the axes which it entails.
The U.S. Pat. No. 6,056,302 from Marc Smith describes an example of a wheel unit for a traditional skateboard. As can be observed in the figures, the unit is formed by a base fixed to the board and this unit to the axis of the wheels by means of a rod which passes through bushings. This configuration allows for the occurrence of a slight inclination of the wheels in relation to the board when the user is supported on one or the other side of said board which allows smooth turns to be carried out in the direction of displacement.
Recently, a new type of skateboard has emerged called the “surfskate”. The difference between a traditional skateboard and a surfskate is fundamentally the type of front wheel unit used. The front wheel unit of a surfskate is configured to allow much greater maneuverability than a traditional skateboard and it is also equipped with a centering spring which exerts an action on the wheels intended to return them to the neutral position thereof. A surfskate has very different behavior to that of a conventional skateboard, allowing the user to propel themselves by simply carrying out oscillatory hip movements similar to those carried out when surfing.
The U.S. Pat. No. 6,793,224 from Carver Skateboard shows an example of a wheel unit for a surfskate. This unit comprises a base couplable to the lower part of a board and an arm coupled to the base which rotates in relation to the same around a first axis. A rod which has a pair of wheels mounted at opposing ends is fixed to said arm and can be rotated in relation to the same around a second axis. A compression spring connected between the base and the arm limits the rotational movement of the arm and returns it towards a central position aligned to the direction of the moving surfskate.
Although the use of this type of wheel unit significantly increases the maneuverability of a surfskate with respect to that of a traditional skateboard, the rotation thereof continues being somewhat insufficient. In addition, it must be separated from the board by means of separators enough in order to avoid the wheel impacting the board. Ultimately, the construction of the unit is complicated and this makes the maintenance and repair operations difficult to carry out.