Chubb detector lock

A Chubb detector lock is a lever tumbler lock with an integral security feature, a re-locking device, which frustrates unauthorised access attempts and indicates to the lock's owner that it has been interfered with. When someone tries to pick the lock or to open it using the wrong key, the lock is designed to jam in a locked state until (depending on the lock) either a special regulator key or the original key is inserted and turned in a different direction. This alerts the owner to the fact that the lock has been tampered with.

Any person who attempts to pick a detector lock must avoid triggering the automatic jamming mechanism. If the automatic jamming mechanism is accidentally triggered (which happens when any one of the levers is lifted too high) the lock-picker has the additional problem of resetting the detector mechanism before the next attempt to open the lock. This introduces additional complexity into the task, increasing the degree of lock-picking skill required to a level which few people have. The first detector lock was produced in 1818 by Jeremiah Chubb of Portsmouth, England, as the result of a government competition to create an unpickable lock. It remained unpicked until the Great Exhibition of 1851.