This is an example of the Chubb Detector lock in it’s final, or definitive form. This example being circa 1860. It is the type most usually found by collectors as large quantities were made and the design continued in mainstream production until the early 1960’s. It may have been produced after that date for Government orders etc.
It’s strength lay in it’s simplicity and ease of manufacture, especially compared with some of the earlier patents. The design incorporated three main devices to frustrate attempts to pick the lock.
1 : The barrel & curtain, closes off the keyhole and restricts the movement of picking tools.
2 : False notching on the leading edge of the levers and the edge of the bolt stump frustrate the tentative picking process.
3 : And finally the detector itself which will engage if any lever is overlifted, and in doing so prevent the lock being opened until it is reset - with the locks correct key.
Below the lock is shown with the detector engaged, just as would occur if a lever is overlifted. The design of this lock is a result of the attacks made upon it’s predecessors by A.C.Hobbs & others and it was born of necessity. I doubt Hobbs would have picked this design with the tools he had at his disposal when he defeated the New Patent design.
