Clamping device and machining unit comprising such a clamping device

A clamping device for clamping a workpiece or a tool or, more specifically, a tool holding fixture in a machine part of a machine tool includes a tension rod slidably mounted within the machine part; a clamping set movable by the tension rod between clamped and released positions; a tension spring dedicated to the tension rod so as to generate the pull-in force of the clamping set; and a release mechanism, by which the clamping set can be moved against the force of the tension spring into the released position by the tension rod. To make possible effective clamping at optimum force, the tension spring is clamped between first and second rod parts of the tension rod. The second rod part can move relative to the first rod part, and, as the clamping set moves into the released position, is compressed on both ends by the release mechanism by moving the two rod parts in opposite directions.