Locking device for door lock bolt in event of attempted house breaking

摘要

The door lock bolt locking device comprises a plate (9) movable between a door leaf and the lock casing (1). The plate has an opening of corresponding shape to that of the end flange of a protection cover (7) of a lock cylinder. An informer wire (12) is in contact with one part of the external perimeter of the cover so that movement of the plate relative to the cover due to housebreaking causes the severing of the wire between the flange and the edge of the opening.