inner bearing shell 18 via distance ring 25 so that front roller bearing 2 is protected against extreme stresses the width of ring shaped gap 29 according of the invention is selected on the basis of different constructional and operational parameters so that the loads occurring are introduced into housing 4 via front roller bearing 2 in the conventional way up to a harmless value while the width of gap 29 decreases depending on the magnitude of the axial load above the load critical for roller bearing 2 gap 29 will already be closed so that the axial stress forces are directly introduced into terminating ring 8 from this moment on it is obvious that the widths of gap 29 and circumferential gap 30 are each selected depending on the specific parameters of the respective spindle type similar effects and results will occur when the idle spindle collides with a machine part for example a workpiece due to a lateral relative movement which will result in preferably radial or transverse loads acting on the spindle which were also introduced into the housing only via the roller bearings in the spindle units conventionally used for the protection of mainly front roller bearing 2 circumferential gap 30 according to the invention is provided between distance ring 25 and.