Activating device for screw caps

1. A device for screwing and/or unscrewing a screw cap of a container comprising a first holding device for holding the screw cap, said first holding device including

a first jaw chuck mounted in a jaw chuck housing, said jaw chuck housing being mounted rotatably on a holder;

a threaded plate mounted rotatably within said jaw chuck housing, said threaded plate having a drive shaft;

a drive motor which is coupled to said jaw chuck housing to set said jaw chuck housing into rotational movement; and

jaws arranged in engagement with the threaded plate, such that when said jaw chuck housing is set into said rotational movement relative to said threaded plate, said jaws are moved radially in the direction of or counter to the direction of an axis of rotation of said threaded plate in order to grasp or to release a screw cap,

wherein said first holding device comprises a changeover switch configured to be switched between a first operating mode and a second operating mode,

wherein, when the changeover switch is switched to the first operating mode, said rotational movement of said jaw chuck housing together with a rotation of said threaded plate is allowed, and

wherein, when the changeover switch is switched to the second operating mode, said rotation of the threaded plate is blocked such that said jaw chuck housing is rotated by said rotational movement relative to said threaded plate.

2. The device according to claim 1 , wherein said threaded plate comprises a blocking wheel connected to the drive shaft, said blocking wheel including a recess on an outer side into which a bolt of the changeover switch engages in order to block the rotation of the threaded plate.

3. The device according to claim 1 , wherein said changeover switch comprises a magnetically activated bolt.

4. The device according to claim 2 , wherein said bolt is magnetically activated and does not engage said recess in an energy-free state.