US Patent 7172044 Self-propelled wheel board

A wheel board comprising a wheel (2) with a diameter of 0.2 to 0.6 m mounted on a free wheel (21), mounted on an axle (3) situated on a vertically pivoting arm (4) arranged on the board (1), and mounted freewheeling and driven by a driving drum (17) around which is wound a band (11) that is fixed to said driving drum (17) by a first end and that is connected to the board by its second end, said driving drum (17) being equipped with a return device (19) so that, when the board (1) is not loaded, the central wheel (2) is in a lower position relative to said board (1) and said band (11) is wound around the drum (17) driving the wheel.