as described earlier it is attached by means of the attachments 35 which come to lie in the open oblong openings 32 the holding devices l and r have flat surfaces which are in the form of fitting surfaces by means of which the intermediate support 3 can be positioned precisely on the bearing block with the separating plane 24 between intermediate support 3 and bearing block 2 the holding devices l and r are provided with the fitting surface 311 with which they bear upon corresponding fitting surfaces 811 of the holding devices 25 of the bearing block 2 see also fig4 and 5 the fitting surfaces 311 of the intermediate support 3 together with their corresponding fitting surfaces 811 ensure precise alignment on the bearing block 2 of the intermediate support 3 in the axial direction which is defined by the axles of the supporting ring bearing or also by the axis of the rotor shaft for horizontal alignment the intermediate support 3 is provided with horizontal fitting surfaces 312 which are shown only from the back in fig7 since this is a top view the fitting surfaces 312 are bearing on their counterparts the fitting surfaces 812 of the holding devices 25 of.