Patent attributes
There is an electric motor driven drop bolt having a housing which in use is mounted into a doorway frame and has the bolt pivotal therein by a mechanical drive set in a cage disposed at an operative position. The bolt is pivotal between a locking configuration where the bolt extends outward of the housing to engage in an aperture associated with a door within the frame and an unlocked configuration where the bolt is withdrawn to clear the aperture. The mechanical drive includes a screw shaft rotatable by the electric motor to move a roller nut along the length of the shaft whilst engaging a cam surface on the bolt. To obtain fail safe operation of the drop bolt the cage is slidable in the housing from the operative position to a disengaged position so that the bolt is movable from the locking configuration to the unlocked configuration without operation of the mechanical drive.
