Abstract: A tool unit includes a tool head, a motor and a switching drive for the head. The head has a first section with first blades and a second section with second blades. The second section is movable to and fro between a passive and an active position relative to the first section, the second blades being retracted in the passive position, and the second blades projecting axially beyond the first blades in the active position. The drive includes an electromagnet and an actuating armature made from magnetically attractable material and is arranged in the region of action of the electromagnet. The electromagnet is positioned between the head and the motor and is fastened to a housing part of the motor such that it cannot be rotated. The armature is connected fixedly to the second section. A gap remains between the electromagnet and the armature in the passive and active position.