How did ancient Egyptian pin-tumbler locks work?

The ancient Egyptian pin-tumbler lock, which dates back approximately 4,000 years, functioned using a simple but effective gravity-based mechanism.1

Mechanism of the Egyptian Lock

The device consisted of a large wooden bolt used to secure a door. This bolt featured a slot with several holes on its upper surface. An assembly attached to the door held a series of vertical wooden pins designed to drop into these holes, effectively locking the bolt in place.1

To unlock the door, a large wooden key—resembling a toothbrush—was used. Instead of bristles, the key featured upright pegs that corresponded precisely to the arrangement of the holes and pins.1

Operation

1. The key was inserted into a keyhole located beneath the vertical pins.1
2. The user lifted the key, causing its pegs to push the pins upward and out of the bolt's holes.1
3. Once the pins were cleared, the bolt could be slid back to open the door.1

This "falling-pin" principle remains a fundamental concept in modern security, serving as the basis for the Yale lock.1