Ancient to modern
The pin tumbler lock is a keyed lock based on an ancient Egyptian lock design. A wooden key would be inserted into a wooden lock that required the right notches on the key to line up pins that would then move into the correct position to allow the wooden bolt to be removed.
Like the lever tumbler lock, a pin tumbler lock requires the correct key to be inserted into the lock and the levers or pins to move into place in order for the plug in the cylinder to rotate to release the bolt.
The first modern pin tumbler lock was patented by Linus Yale Sr in 1848. It featured a cylinder with an internal plug and had a set of pins that would open a lock with the correct serrated key. This style of lock was developed further by Linus Yale Jr in 1861.
How does the lock work?
A pin tumbler cylinder lock consists of a rotating plug inside a cylinder and a set of pins that, when aligned correctly, will allow the internal plug to rotate. When a lock has no key inserted the pins obstruct the cylinder and it cannot move. If the incorrect key is inserted the pins will not align and therefore the cylinder will still not rotate. When the correct key is inserted, the serrated side pushes the pins into the correct position, they no longer restrict the movement of the plug and the bolt is released. There are thousands of possible combinations, which made the pin tumbler an ideal lock for mass production.
The lock was safer than many of the traditional locks at the time because it did not have a large keyhole that was easy to tamper with. This made it difficult to break the lock with tools and explosives.
Modern Locks
The name Yale is still synonymous with night latch style locks, which are often referred to as Yale locks even if they are made by a different company. This type of pin tumbler lock is found on nearly all residential properties and they are often accompanied by deadbolt locks to ensure maximum security.