An upper support mechanism (27) is fixed to sides of the vehicle bodywork and supports the steering column (21). It has an operating lever (33), which selectively can adopt a position in which the movement of the steering column is possible in an axial direction or a position in which the steering column is fixed. A lower support mechanism (38) is fixed to the sides of the vehicle bodywork and supports the steering column. It contains a lower bearer (38) fixed to the vehicle bodywork. A friction component (34) is provided between the lower support and the steering column. It has a first position in which it is in frictional engagement with the lower bearer and the steering column, preventing the movement of the steering column. In a second position the frictional engagement is released.
