Abstract: The clamp element includes a rapid feed device combined with a force amplifier. The force amplifier is surrounded by a rotatable feed sleeve, which engages through an external thread in a female thread of a surrounding housing. A first tightening member is fixed and a tightening clamp member is rotatably arranged in the feed sleeve. Two tightening pins are arranged between the two tightening members. The tightening pins are supported on the second tightening member the smallest possible distance from the feed sleeve axis. An actuating and tensioning rod is passed either through a central aperture in the first tightening member (FIGS. 7-11) or through two diametrically opposite, lateral aperture of the first tightening member (FIGS. 1-6).