: if all door locks are different and different keys open different locks, how does a universal key work?

Question

: if all door locks are different and different keys open different locks, how does a universal key work?

In: Engineering

Answer 1

The lock opens because the “rings” inside align. The way some locks are made is that there are two sets of rings – one unique for each key, and one same for the master key.

Longer answer is, lock is a small cylinder inside large cylinder, and there are “pins” going between them that prevent the inner cylinder from turning. Correct key pushes them out, thus freeing inner cylinder and allowing it to rotate. To enable master key, you just add an additional cylinder, which results in pins having 3 total possible positions – “at rest”, “unique opened” and “master opened”.