Watching a lock’s mechanism movements

[ted johnson]

Probably all of us have an idea of what goes on inside a clasp lid lock as the key turns. The lever tumblers go up & down and the lock-bolt slides. I decided I wanted to physically see it happen. So, I replaced the lock mechanism cover with a piece of Plexi-glass, not a very easy job, and a nail for the lever spring arm. I just used whatever I found around. It’s an Eagle A50M30 lock with 3 lever tumblers, but all brands work the same, except Excelsior.

The below pictures illustrate the movements. 

The pictures may get out of order when posting, so here’s the order to view them when the lock is unlocked, 12:14, 12:08, 12:05, 12:00, 11:52, 11:47. 

12:14 -- the lock is in the unlocked position with the key turning counterclockwise and just starting to make contact with the spring-loaded lever tumblers. It’s also just starting into the bottom opening in the lock-bolt, which is used for sliding it.

12:08 – the key has raised the 3 levers to their maximum height, which allows the lock-bolt to now slide. You can see that the levers have very little clearance between the lock-bolt’s top hasp flange and its bottom vertical tab.

12:05-12:00 -- the key is maintaining the lever’s heights and moving the lock-bolt toward the locked position,

11:52 – the lock-bolt has slid to the locked position.

11:47 – the key has allowed the spring-loaded levers to come back down so the lock-bolt can’t slide any more.