Disclosed is a mounting device (6) including a receiving opening (8) with a circular inner locating surface (10) which is coaxial with the axis of rotation (3) and serves for engagement with radially outer vertices (24) of the polygon profile of a holding pin (23). Arranged adjacent to the inner locating surface is a positioning disk (14) which has an opening (15) coaxial with the axis of rotation (3) and of such polygonal shape and size that the polygon profile of the holding pin (23) engaging in the opening (15) is supported in the opening (15) in a manner preventing relative rotation.