User:Willh26/sandbox/Yale lock (company)

A Yale Lock (sometimes referred to as a night latch) is a type of lock commonly found in the United Kingdom and other parts around Europe. The lock is designed with a key mechanism on the outside of the door and a spring loaded latch with thumb turn on the inside. This design allows people to leave and lock building without having a key.

Design
The external part of a Yale lock consists of a type of pin tumbler lock in the form of a replaceable mortised cylinder. This allows the owner of the lock to easily change their door key without the need to replace the entire locking mechanism. The internal part of the door consists of a surface mounted sprung latch. This latch allows the door to be locked from the outside without a key.

The internal latch also has a "switch" known as a snib. The snib allows the door to be double locked, preventing access from the outside even if someone has a key.

The snib also gives a "hold" feature which disables the bolt allowing passage from the outside without a key.

Vulnerabilities
Yale locks are vulnerable to a particular type of lock bypass attack known as shimming, where an object such as a credit card or laminate piece of plastic is used to retract the locking bolt from the frame.

More modern types of Yale lock have extra security measures to ensure that shimming cannot be done and are designed with a dead latch mechanism. Once the door is closed, a small locking post is depressed which causes the latch bolt to dead lock.

British Standards
The new models of night latches conform to BS 3621 & BS 8621