Pin tumbler
Pin-tumbler
A cylinder based lock design that uses movable pins to prevent rotation of the plug. A key is used to properly elevate pins to allow the plug to rotate and the locking bolt to be retracted.
The pin-tumbler is currently one of the most widely used lock designs in the world. Minor changes to the positions of pin-tumbler components is the basis for dimple and axial/tubular lock designs.
History
Pin-tumbler locks were originally invented in ancient Egypt. The design used a series of single pins that, when locked, would prevent movement of a bolt by resting inside the bolt itself. The key was used to raise pins out of the bolt, allowing it to retract. This was the first use of a shear line, a major discovery that is the basis for all cylinder based locks in modern use. Early pin tumbler locks, bolts, and keys were all made with wood, but eventually brass and iron were used. Many cultures adopted the design throughout history, but it would not be widely used until Linus Yale Sr. and Linus Yale, Jr. modified the pin-tumbler design in the mid 1800s.
Linus Yale Sr. improved the Egyptian design with the idea of pin pairs. In the original lock pins were required to be raised high enough to clear the bolt, but were not checked to make sure they weren't raised higher than necessary. The addition of a second pin in each chamber allowed for positive locking when components were raised too high. In this design, the key had to properly raise the pin pairs so that they could separate at the shear line, allowing the locking bolt to be retracted. Yale Sr. also added springs above the pin pairs to force them down to their locked position when no key is inserted.
Principles of Operation
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Vulnerabilities
Pin-tumblers are vulnerable to a wide variety of attacks. The specifics of the pin-tumbler design and manufacturing tolerances will determine the exact vulnerabilities present, but most pin-tumblers are vulnerable to at least one or more of the following:
- Lockpicking
- Pick Guns
- Key Bumping
- Tryout Keys
- Comb Picks
- Impressioning
- Decoding
- Bypass
- Desctructive Entry
