Glossary of locksmithing terms

This is a glossary of locksmithing terms.

Glossary

Bolt stump
A bolt stump is a rectangular part of a lock located above the talon, and passes through the slot in the levers as the bolt moves. This part is welded or riveted onto the lathe in some earlier locks. Modern lock manufacture allows this to be machined in. Most are directly cast into the blank and then milled smooth for final use.[1]
Break
A break in the pins is a separation in one or more sections of the pin used to encode the lock for a specific key or set of keys in a master keying system.
Face plate
A metal plate on the lockset itself (on the door, not the jamb) is called a face plate.
Glass relocking device
A glass relocking device is a piece of glass, usually tempered, placed where it might be expected to break in a burglary attack. It is attached, usually with wires, to one or more spring-loaded bolts, which are often randomly located. A drill or torch may break the glass, releasing the bolts.
Lock housing
The lock housing, also known as the bible[2], refers to the part of the lock that does not move when the lock is opened.
Relocking device
A relocking device (RLD) (a.k.a. "external relocker") is an auxiliary locking device intended to be activated during an attempted burglary of a safe or vault. Such a device will keep a safe or vault locked even if the primary lock is defeated. This independent mechanism is designed to maintain the locked state of a safe even if the lock itself is destroyed. This auxiliary locking device usually consists of a spring-loaded bolt of some type, held in check by a bracket or cable that is rigged to release the mechanism in a burglary attempt. The device will either block the main boltwork from retracting or block the door from opening. Glass relockers are one of the most common types of relockers used in today's safes. Relockers are typically designed for one-time activation, meaning that once they are triggered the device is locked "permanently" and can only be opened by brute force.
Security pin
A security pin is a pin designed in a non-standard way to attempt to prevent the lock from being picked.[3] Examples of security pins include serrated pins, spools, and mushroom pins.[3]
Shear line
In a cylinder lock, the shear line (also known as the split line in Australia), is where the inner cylinder ends and the outer cylinder begins. When a break in the pin is reached by picking, the pin will "hang" at the shearline due to the space between the inner and outer cylinder. This "imperfection" in the lock mechanism is an unavoidable defect in the manufacturing process that allows for lock picking.
Strike plate
A strike plate is a metal plate affixed to a doorjamb with a hole or holes for the bolt of the door. When the door is closed, the bolt extends into the hole in the strike plate and holds the door closed. The strike plate protects the jamb against friction from the bolt and increases security in the case of a jamb made of a softer material (such as wood) than the strike plate. Some strike plates have their hole size and placement calculated so a spring-bolt extends into the hole, but an adjacent anti-retraction device remains depressed, preventing the bolt from being retracted unless the lock is turned.
Thermal relocking device
Designed as a defense against torch attacks, these are simply relocking devices equipped with a fusible link designed to melt and release the relocking device if the temperature inside the door exceeds a certain temperature (usually 65 °C), as would happen in a torch attack.

References

  1. ↑ Mick Friend (2004), The Encyclopaedia for Locksmiths, Authors OnLine, Ltd., p. 34, ISBN 0-7552-0117-5
  2. ↑ "How To Pick Locks: The Definitive Guide To Lock Picking". United Locksmith. 18 September 2017.
  3. 1 2 "Security Pins". Art of Lock Picking. 24 February 2016. Retrieved 8 October 2018.
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