Abstract: A clamping sleeve/tensioning device comprises a clamping sleeve that is positioned inside a conical centering opening of a housing body. A chucking mechanism with rotational body is used to tighten or release the clamping sleeve. The rotational body is provided with a central opening, having an internal thread or an external thread, which directly engages in the clamping sleeve. The rotational body preferably is supported via a roller bearing on a corresponding bearing surface of the housing body. The rotational body is driven via a reducing gear, for example via a worm. As a result, high tensioning forces can be generated in connection with the relatively small diameter of the tensioning thread and the small conical angle. The small diameter of the tensioning thread ensures a low thread friction.