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Warded lock


A warded lock (also called a ward lock) is a type of lock that uses a set of obstructions, or wards, to prevent the lock from opening unless the correct key is inserted. The correct key has notches or slots corresponding to the obstructions in the lock, allowing it to rotate freely inside the lock.

The warded lock is one of the oldest lock designs which can be found as far back as ancient China and Rome. During the Middle Ages they were used prolifically on monasteries where, because money and time were not issues, their complexity grew. Warded locks are still in use today in the UK and Ireland for low security applications, and on heritage sites such as ancient monuments and churches to preserve original features, with primary security being provided by other means such as a lever lock mechanism installed alongside.

In a basic warded lock, a set of obstructions, often consisting of concentric plates protruding outwards, blocks the rotation of a key not designed for that lock. Warded locks may have one simple ward, or many intricate wards with bends and complex protrusions; the principle remains the same. Unless the notches or slots in the key correspond to the wards in the lock, the key will strike an obstruction and will not turn.

Additionally, a series of grooves on either side of the key's blade limit the type of lock the key can slide into. As the key slides into the lock through the keyway, the wards align with the grooves in the key's profile to allow or deny entry into the lock cylinder. Although this is not commonly recognized when discussing warded locks, it is more applicable to current locksmithing applications such as pin-tumbler or wafer-tumbler locks.

In double sided locks the centre of the key shaft is solid and protrudes past the end of the bit which slots into a hole on the opposite side of the lock. Double sided ward locks nearly always have perfectly symmetrical bits. For single sided locks a cylindrical post is typically located in the center of the lock. Its purpose is to provide a point of leverage for rotating the key, and to help correctly align the key with the wards. The key has a corresponding hole which fits over the post.


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