Abstract: A transportation device comprising two longitudinally extending frame parts adjustable relative to each other in a transverse direction, individually driven drive means for each of said longitudinally extending frame parts and having obliquely positioned ground contact elements for driving the device in an optimal direction, each of said drive means comprising at least one drive wheel disposed on the frame part for moving the frame part relative to the other frame part, and displacing means for displacing at least one of the first and second frame parts relative to each other in the transverse direction.