Glossary

Back plate

A metal plate, used mostly to fasten a night latch cylinder to a door, using fixing bolts.

Backset

The distance from the edge of a door (or the forend) to the centre of the keyhole or cylinder.

Bolt

The brass or steel section of a lock that is operated by rotating the key or knob and extends from the lock case into a cavity in a frame, preventing the door or window from being opened.

Box striking plate

A metal plate with a recessed box that is fitted flush on a door jamb or frame, to protect the bolt head from attacks with jemmying tools.

BS 3621 : 1998

The British Standard for Thief Resistant Locks.  Generally, this is recognized as giving the maximum protection available to the majority of both domestic and commercial premises. Many insurance companies recognize this and reduce premiums accordingly.  Some insurers may provide cover only if BS 3621 : 1998 locks are fitted.

Cam

A component attached to a camlock, usually a metal plate or tailpiece, that rotates with the movement of a key.

Cam lock

A simple yet very versatile lock in the form of a cylinder that uses a cam to secure a door or panel.

Collar

See protective collar.

Combination lock

A lock that is operated by setting a particular sequence of numbers, rather than with a key.

Cylinder

A device, operated by a key, which extends or retracts the bolt or latch of a lock.

Deadbolt

A bolt that when locked resists direct pressure applied to it in the unlocking direction.

Deadlock

A lock that incorporates a deadbolt.

Disc tumbler lock

A lock with a number of flat plates that must be correctly aligned by the operation of the key before it can be unlocked/locked.

Euro Profile

A type of cylinder that has a profile shaped like an enlarged traditional keyhole.

Escutcheon

A surface mounted trim that enhances the look of a keyhole. Not necessarily surface mounted.

Ferrule

See Rose.

Forend

The part of a mortice lock, by which the lock is fixed to the door.

Key control

Ways of preventing unauthorised persons from obtaining, duplicating or distributing a key.

Keyed alike

See Keyed to pass.

Keyed to differ

A group of locks operated by different keys.

Keyed to pass

A group of locks operated by the same key.

Keyway

The opening in a lock that is shaped to accept the proper key.

Latch

A bevelled, spring-loaded fastener that automatically engages as a door closes and is withdrawn by use of a key or handle.

Levers

Levers are components in locks not operated by a cylinder, which lock in place the bolt or latch.  Generally, the higher the number of levers, the more secure the lock. Typically, interior doors have two or three lever locks and exterior door locks are fitted with five to seven levers.

Master key

A key that will open any lock in a suite of locks, each of which is also operated by an individual key.

Mortice lock

A lock recessed into a door or window.  A mortice lock may be a key operated lock only (a deadlock) or combined with a latch operated by a door handle (a sash lock)

Mushroom drivers

Specially shaped pin tumblers used in lock cylinders to resist picking and manipulation.

Pin tumblers

A set of pins of varying lengths that prevents a cylinder being operated without the correct key. 

Protective collar

A chamfered ring that fits around the head of a cam lock to improve its security.

Push button lock

A type of combination lock featuring buttons that must be pushed in a specific sequence to open it. 

Rim lock

A lock mounted on the surface of a door or drawer, rather than recessed into either.

Rose

A circular band that provides a neat finish to the hole that accepts a lock in a door or frame.

Sashlock

A lock with both latch and deadbolt function.

Shackle

A part of a padlock that passes through an opening in an object or fits over an object and locks into the case.

Snib

A small catch or button on a lock to hold the bolt in either the withdrawn or locked position.

Stop-plate

A metal plate fitted to the back of a cam lock that determines whether the lock rotates clockwise or anti-clockwise and 90º or 180º. 

Striking plate

A metal plate that is fitted flush on a door jamb or frame, to protect the frame and accept the latch or bolt.

Tumbler

The moveable locking elements, commonly levers, discs or pins incorporated into a lock to prevent an incorrect key or other device from activating the lock mechanism.

UL listed

Underwriters Laboratories Inc. is an independent, not-for-profit organization that tests samples of products for conformity to safety standards.