the support ring 46 further includes two substantially circular portions which fit into the annular groove 39 and which are connected with one another by a bridge portion 51 which fits into the groove exit portions 44 of the respective bearing members 16 to 19 and extends across the interspace delimited by the respective flat faces 40 of the respective bearing members 16 to 19 as shown in fig4 the support ring 46 is substantially u shaped in cross section so that it bounds a cross sectionally u shaped recess the sealing body 47 is partially accommodated in the u shaped recess of the support ring 46 the sealing body 47 has substantially the same configuration that is it extends along substantially the same course as the support ring 46 but has a different cross sectional shape as shown in fig8 the sealing body 47 has as considered in the cross section a mounting zone 53 which is relatively wide and which is fittingly received in the u shaped recess in the support ring 46 the sealing body 47 further includes in its central zone two transversely extending web portions 54 and 55 the distance between the free end faces of the web portions 54 and 55 substantially corresponds to the width of the support ring 46 finally a relatively narrow but relatively long zone 56 of the sealing body 47 adjoins the web portions 54 and 55 across from the mounting zone 53 as may be seen.