internal movement of the tie beams 14 in the shell 13 in relation to one another so that transverse forces in the tie beam 12 can be reduced however it may also be desired for the tie beams 12 to be securely embedded in the shell 13 accordingly a shell material or a production method is selected allowing the shell material to be effectively bound into the tie beam on account of its construction the tie beam 12 has a ratio of its width b in the axial direction of the drive wheel 4 1 to its height h in the radial direction of the drive wheel 4 1 of two equally this ensures small radii of deflection and nevertheless sufficient flexibility of the suspension in particular in its width direction this increases in particular also the ease of installation of the more flexible suspension 12 which can be applied to the wheels 4 1 to 4 4 more easily in order to increase the ease of installation still further the suspension is embodied symmetrically with respect to its transverse or vertical axis which is positioned perpendicularly to its longitudinal direction and runs in the width or vertical direction so that it can also be applied turned through 180 u00b0 and can loop around successive wheels in opposite directions with identical outer surface contours the suspension 12 is received in a flute 15 of the drive wheel 4 1 in such a way that it is in the example positioned almost completely within the flute 15 touches the.