W.A. Martin

The Inventor of the Lock

Washington A. Martin didn't actually invent the lock, the chinese did. What Martin did was simply improve the 4,000 year old chiniese bolt and the egyptian pin-tumbler.
pin_tumbler.png
Without a key in the lock, the driver pins (blue) are pushed downwards, preventing the plug (yellow) from rotating.
pt2.png
When an incorrect key is inserted into the lock, the key pins (red) and driver pins (blue) do not align with the shear line; therefore, it does not allow the plug (yellow) to rotate
pt3.png
When the correct key is inserted, the gaps between the key pins (red) and driver pins (blue) align with the edge of the plug (yellow).
pt4.png
With the gaps between the pins aligned with the shear line, the plug (yellow) can rotate freely.