Patent ID: 7052054

Claim:
A drop bolt for securing a door or other movable barrier, said drop bolt having a housing which in use can be mounted into a frame for said door or other movable barrier and said housing having a bolt which is pivotal therein by an electric motor powered mechanical drive when set in a cage at an operative position, the bolt being pivotal between a locking configuration where the bolt can extend outward of said housing for engagement in an aperture associated with said door or other movable barrier and an unlocked configuration where the bolt is withdrawn clear of said aperture, said mechanical drive including a screw shaft rotatable by the electric motor to move a roller nut along the length thereof whilst engaging a cam surface on said bolt and to obtain fail safe operation of said drop bolt the cage being slidable in the housing from said operative position to a disengaged position whereby the bolt is movable from said locking configuration to said unlocked configuration without operation of said mechanical drive.