Security lock

摘要

The lock incorporates a counter mechanism, an indexing lever, a guide plate, and a cover welded to a baseplate. When the bolt of the lock is moved to the left or right as far as it will go, the lever (9) is moved also, causing the number (6) to index for one place. A counter with nine or ten numbers can be used, to avoid resetting to the old number. With a safe, two counters can be provided, to check if anyone has stopped in the room at the relevant time.