A clamping unit, in particular for use in a machining center, or a turning or milling center, wherein the clamping unit comprises an external housing (12), preferably having a cylindrical basic design, an internal housing (15) accommodated in the external housing (12), and an internal cylinder (11) that is retained in the internal housing (15) such that it can be displaced in a vertical adjustment direction A when in the operating state, which is designed for transferring a pressure or tensile force for clamping purposes, wherein the internal housing (15) is supported in the external housing (12) by means of springs (13, 14), and is supported with respect to the external housing (12) such that it can be displaced in the adjustment direction A, and thus forms a spring force storage unit (21), and wherein an electric motor (16) is disposed inside the clamping unit, integrated therein, preferably encompassed by the external housing (12), furthermore, preferably accommodated inside the internal housing (15), in order to apply a force in the adjustment direction A to the internal cylinder (11) via drive means (17-20) disposed therein.