Mondo Knows Facts
Master keys work with extra pins in the lock
Two shear heights per chamber let one key open many different locks A master keyed lock has an extra split pin in each chamber, so the cylinder has a change key shear line and a master key shear line. The individual key lifts each stack to the lower line while the master key lifts it past that to the upper one. Hotels and offices use the system so staff carry one key for many doors. It sits in Mondo's everyday life collection, one of 200 facts that each trace back to the reference below.
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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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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 cylindersDoor key notches act as mechanical physical passwords for locksGround key blade cut depths lift internal door pins to the exact shear lineLever locks open only when every lever is liftedEach key cut raises one lever until its gap lines up with the boltDoor closers slow the swing with oilA spring shuts the door while hydraulic fluid meters how fast it movesPublic doors often open outward for escapeA door swinging with the escape route empties faster than one pulled inwardStair handrails sit about 900 millimetres above the stepThe height suits a relaxed grip with the arm slightly bent for support
🧭 Everyday Lifefact 136 of 200
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Tags: locks, keys, buildings
Master keys work with extra pins in the lock: the short answers
- Where does this come from, and can I check it?
- Two shear heights per chamber let one key open many different locks. 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.