US Patent 6983962 Deadlock arrangement for locks

A deadlocking assembly for use in locks that includes a rack supporting a bolt and a driving or pinion gear that drives the rack. Both the rack and the pinion gear have teeth that intermesh. The pinion gear further includes two arms, one of which acts as a stop when extending the bolt and the other that acts as a deadlock. When in the deadlocked position, forcing of the bolt is prevented by the other arm since the pinion gear teeth and the rack gear teeth at that position do not intermesh. A tab is further used to limit further rotation of the pinion gear.