Where does this come from, and can I check it?

Each dial turns a disc with a gap, and all the gaps must meet at once. The figure is taken from Encyclopaedia Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a everyday life fact?

Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Combination locks release when internal notches line up

Each dial turns a disc with a gap, and all the gaps must meet at once Inside a dial combination lock, each numbered wheel is fixed to a disc with a notch cut in its rim. Turning the dials to the code lines the notches up into a single slot, and the shackle or bolt can then drop through. Because the discs are stacked with spacing washers, a careful hand can sometimes feel the notches and open the lock without the code. It sits in Mondo's everyday life collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Encyclopaedia Britannica

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Technology trivia General Knowledge trivia

More facts like this

Cylinder pin-tumbler door locks align split pins along a shear lineKey ridges lift spring-loaded split pins to unlock door cylinders Door key notches act as mechanical physical passwords for locksGround key blade cut depths lift internal door pins to the exact shear line A padlock shackle is held by a notchBall bearings or a latch drop into a cut groove to lock the hardened loop A deadbolt has no spring, unlike a door latchThe latch slides back by spring and bevels to close, but the bolt does not Long door cylinders can be snapped at the middleThe weak point sits where the lock body meets the handle plate A zipper slider is a tapered Y channelThe two rows enter separately and leave interlocked through a narrow throat

Tags: locks, mechanisms, security

Combination locks release when internal notches line up: the short answers

Where does this come from, and can I check it?: Each dial turns a disc with a gap, and all the gaps must meet at once. The figure is taken from Encyclopaedia Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a everyday life fact?: Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.