laterally in contact on the outer races 24 b of the roller bearings 24 aside from the inner diameters of the spacer rings 26 their side walls are set back stepwise toward the outside and the outer diameter is less than that of the outer races 24 b such that on the outer circumference of the stationary spacer rings 26 no contact with adjacent rotating structural parts in particular with the roller segments 12 is possible the axial dimensions are such that between the roller segments 12 annular gaps 29 with a gap width u201c s u201d of for example 0 2 mm are formed relative rotational movements between the individual roller segments 12 are thereby made possible with reference to oppositely disposed imaginary fixed points of the two immediately adjacent roller segments 12 of both groups 10 and 11 in the proximity of the coupling element 9 said fixed points move such that the width of a gap 30 in the proximity of the coupling element 9 fluctuates during the rotation for example periodically between 0 89 mm in fig2 below and 1 53 mm above the linear alignment of shell lines m 1 and m 2 remains unchanged during the rotation of the roller segments it is here important that through this bridge like structuring the circumferential speed of the roller segments 12 in the proximity of their shell lines m 1 and m 2.