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A List of Common Phrases that apply to Locksmiths

Alike change

More than one lock or latch which can be operated by the same key.


All to pass

Often referred to as “locks to pass”, i.e. several locks which can be “passed” or opened by the same key.


Armoured cylinder

A high-security cylinder is protected or ‘armoured’ against a drill attack using hardened pins and plates.


Automatic deadlocking

A small auxiliary bolt next to the main bolt hits the striking plate or staple and is pushed in every time the door is closed. This action automatically holds the main bolt in the locked position.


Auxiliary bolt

An additional bolt that is activated by the strike when the door is closed automatically deadlocks the latch bolt against end pressure.



The feature of a door closer unit that prevents shock and possible damage when the door is forcibly opened.



The plate, fixed on a door, to which the moving parts of a lock or latch are attached.



The horizontal distance from the edge of the door to the central line of the cylinder keyhole.


Bathroom lock

A lock with latch bolt operable on both sides by furniture and deadbolt operated from inside only; usually by thumb turn.


Bit (of a key) or key bit

That part of a key that is specially shaped or notched to operate the mechanism of its particular lock or latch.


BitingThe shaping or notching of a key blank to transform it into a key to operate its lock or latch.


Blade (of a key)

That part of a cylinder or lever key which is to be or has been notched.


Blank (key) or key blank

A partly made key, which has been shaped to enter the keyhole of a certain type of lock or latch, but of which the blade has not been finally notched to operate any individual lock.



The part of a lock or latch which provides the fastening or engagement by protruding from the case or forend to engage in the staple or striking plate.


Bow (of a key)

That part of the key which is held in the fingers when operating the lock or latch.


Box strike

A strike in which the bolt recess is enclosed or boxed, thus covering the opening in the jamb.


Cabinet lock

A generic term to include all locks of any type for use on pieces of furniture, such as cupboards, drawers, chests, boxes and the like.



Usually, a tongue fixed to the end of the plug of a cylinder lock or latch.



That part of a lock or latch containing the mechanism.


Casement window

A window with a sash hung about a vertical axis by hinges at the side.


Center hook bolt

On Chubb multipoint locks – used to grip the door sash and frame together facilitate compression.


Change keys

The key which opens one particular lock. Usually, a term used with Master-Keyed Suites.


Claw bolt

A type of deadbolt having claws which swing outside when the bolt is shot. Such locks are usually fixed to sliding doors.


Close shackle padlock

A padlock the body of which is built up so that the minimum amount of shackle is visible when locked. Improved security against forcing or use of bolt-croppers.


Clutch head screws

See one-way screws.


Concealed fixing

Once fitted the fixings of the lock or security device are hidden from view.


Connecting bar

The thin metal strip fitted to the rear of the cylinder plug which operates the spring bolt in a cylinder rim lock. It passes through the thickness of the door and is usually indented at intervals to ease shortening to the correct length.


Connecting screws

The two screws which fix the cylinder body to the mounting plate.


Construction keying

Systems used to allow contractors to gain entry to a building during construction but to prevent entry by the same contractors after the building has been occupied or handed over.



The mechanism that operates the lock.


Cylinder key

A key, having a bow and long blade in which V cuts are made along the upper edge to operate the pins and drivers in a pin tumbler mechanism.


Cylinder mortise lock

A mortise style lock operated by either a euro or oval cylinder. Most commonly used in master key systems. Available as either a deadlock or a sash lock (door lock).


Cylinder raised

A shaped metal disc that surrounds the outer face of the cylinder of a cylinder mechanism assembly. Usually stands slightly proud of the outside face of the door.



A bolt that is not activated by a spring. When locked the bolt cannot be returned by end pressure.



A night latch or latch, the spring bolt of which can be locked (or deadlocked) by key or other means.



A single bolt mortise lock which can be used to supplement a standard cylinder rim lock on the front door.



On cylinder rim locks with this function, once you have left the house and closed the door, insert the key in the cylinder and give it an anti-clockwise turn. This deadlocks the bolt preventing it from being pushed back.


Delayed action

A feature of a door closer which holds the door in the open position for several seconds before the closing action commences. This feature is ideal for use by the handicapped, the aged and people with prams, trolleys etc.



An abbreviation of “different combinations” (see key combinations).


Disc tumbler locks

A cylinder lock having discs instead of pin tumblers.


Disc tumblers

The small shaped discs (usually of metal) in the disc tumbler mechanism which are the means of providing different combinations.


Double locking

The manual means by which the latch bolt on a cylinder rim lock is deadlocked. Insert the key in the outside cylinder and give it a reverse turn. The inside handle is now locked and unopenable until the key is reinserted into the outside cylinder. Prevents unauthorized entry by someone breaking adjacent glass, reaching in and turning the handle.


Double throw latch bolt

On Chubb multipoint locks – an extra key turn projects the latch a further 6mm and secures it.

Drill resistant

Locks and cylinders can be protected against drill attacks by utilizing hardened steel plates and pins.



Usually the upper of each pair of pin tumblers in the cylinder mechanism. The lower are known as pins.


Dummy trim

The non-operating door trim is installed for appearance or as a door pull only.


Easy action

A lock is designed so that only light spring pressure is required to move the bolt.


Electric strike

An electrical device that replaced a regular lock strike to enable a door to be released by remote control.


Emergency key

A key supplied with Hotel locks. These locks have a feature that, when applied, prevents entry by normal service keys, master keys or grandmaster keys. At all times entry can be gained by the emergency key which suits that group of locks.



The cover for the keyhole of a mortise or similar lock. (Also known as a rose).


Euro cylinder

The security device which operates a euro profile cylinder mortise lock. Supplied as either single, double or single with thumb turn operation.



A strip of metal fixed to the outer edge of a mortise lock which fits flush with the door edge.


Final exit door

The exit door through which entry must later be obtained, and so cannot be bolted. Usually the front entrance door. N.B. – As one must rely on the lock only for security, a high-security lock must always be fitted to a final exit door.



That part of the lock mechanism contains a square hole to admit the spindle (to which door handles are attached) which pulls back the spring bolt when turned.


Force resistant

Cylinder rim locks that have an automatic deadlocking feature are protected against a jimmy attack because the bolt is held in the locked position every time the door is closed. High-security cylinder rim locks also have an extended striking plate giving a stronger fixing to the frame and so are resistant to an attempt to kick the door open. High-security mortise locks have a box striking plate too.



That part of the lock or latch through which the bolt(s) protrude, and by which the lock or latch is fixed to the door.


Furniture (door handles)

The additional items needed, which are screwed to one or both sides of the door to enable a lock or latch to be manually operated.


Grand master key

A key within a system that operates all locks in several separate groups that have their master keys.



For some locks (usually specialized locks for use in the commercial sector) the handing of the door to which the lock is fitted must be specified when ordering.


Hasp & staple

A fastening in two pieces to be secured by a padlock. (Also known as a pad bar).


High Security

Same as commercial section high-security locks.


Hold open

The feature of a door closer unit which enables a door to be held in the opened position until released.



A snib, button or other devices that can hold the bolt in the retracted position.


Hook bolts

A lock with a hook-shaped bolt. Such locks or latches are usually fixed on UPVC or sliding doors.


Horizontal lock

A mortise or rim lock having the follower hole further from the forend than the keyhole, and in the same horizontal plane.



The vertical part of a door or window frame. In some areas the top rail of a door frame to as the top jamb.



A term sometimes used for a staple or striking plate.



A small removable device for operating the mechanism of its lock.


Key blank

A partly made key, which has been shaped to enter the keyhole of a certain type of lock or latch, but of which the blade has not been fully shaped to operate the mechanism of the lock.


Key change

A term sometimes used instead of “differ”. The change or difference of the key is generally indicated by numbers and sometimes numbers and letters marked on the bow.


Key combination

This is the number of possible key combinations before the same key is repeated.



The hole into which the key enters to operate the lock or latch. Often referred to as the keyway, particularly in a cylinder mechanism.



Used in conjunction with an electric strike to provide an easy means of Access Control. Most common keypads require a four-digit combination to be entered.



The type of product with one bolt only, the bevelled spring bolt or roller bolt, to latch or fasten the door, but not capable of being locked.


Latch bolt

A bolt having a bevelled edge. (Also see spring bolt).



Door handle used in conjunction with Chubb multipoint locks.


Lever mechanism

A lock mechanism having, as its principal feature, one or more levers.


Lever pad

Door handle used in conjunction with Chubb multipoint locks.



The traditional method by which a mortise lock is operated; 5, 3 or 2 lever mechanisms. The cutting on the key raises the levers until they form a horizontal plane. The deadbolt can then be thrown into the locked position.


Levers handle

Door furniture for use as an alternative to a knob for operating the latch of a lock. Lever handles can be spring-loaded or non-spring loaded. Spring loading ensures the handle returns to the horizontal position after use. Non-spring, loaded handles rely on the springing in the lock.


Lip (of the striking plate)

The projection on one side of a striking plate on the surface of which the spring bolt of the lock or latch first strikes when the door is closed. Usually radiuses or bevelled to guide the spring bolt.



A device operated usually, but not always, by a key, having one or more bolts or other parts to fasten and secure a door, lid, drawer or other parts.



A lock complete with necessary furniture including a spindle, ready for fixing to the door.


Long shackle padlock

A padlock shackle with a greater amount of clearance than the standard shackle.



Applied to the cylinder mechanism to ensure smooth operation. Chubb recommends the regular use of WD40 on moving parts, otherwise a graphite powder for the cylinder plugs.


Master key

A key that will open a series of locks in a Master Keyed Suite.


Master keyed

A lock or latch capable of being operated also by a Master Key as well as its change or servant key.


Mechanism (of locks or latches)

The arrangement of the parts and how they perform to achieve the required security and differing when operated by its key.



A hole cut into the thickness of one edge of a door to receive a mortise lock or latch.


Mortise lock

A lock designed to be recessed into the edge of a door, rather than being mounted to its surface.


Mortise night latch

A hybrid between a mortise lock and a cylinder rim lock/night latch. The automatic deadlocking function using a small auxiliary bolt ensures that every time the door is closed it is locked. Ideal for flat entrance doors.


Multipoint locks

High-security locking mechanism for doors that offers a range of ‘locking points’ often incorporating hooks, rollers, mushrooms and deadbolts.


Mushroom driver

A driver in the cylinder mechanism which has a mushroom-shaped head. These provide a very effective anti-pick element against being lifted by a lock-pick or similar.


Narrow case lock or latch

A rim lock or latch the case of which is made specially narrow, usually less than 75mm wide, for fixing to the narrow stile of a panelled or flush door.


Night latch

A rim or mortise latch with a bevelled spring bolt or roller bolt which shoots when the door is closed but can be withdrawn by key from outside and by knob or lever handle from inside. Usually provided with a stop knob, slide or snib to hold the bolt retracted and to deadlock the bolt when shot in the closed position, even against the action of the key.


One-way screws (or clutch head screws)

Screws with specially shaped heads to prevent removal by conventional screwdrivers.


Oval Cylinders

The security device which operates an oval profile cylinder mortise lock. Supplied as either single, double or single with thumb turn operation.


Passage set

A latch set with knobs or levers on both sides of a door but no locking function.


Passing (or to pass)

Any key which operates a lock is said to pass the lock. If locks are made “alike change” one key will pass all the locks.


Pin tumbler mechanism

The mechanism incorporated in a Cylinder Rim Lock or Padlock. The cylinder houses the pins and drivers under spring pressure. The correct key lines up the plug and cylinder, thus allowing the plug to rotate and the lock to be operated.



Usually the lower of each pair of tumblers in the cylinder mechanism. The upper is known as drivers.



The part of the pin-tumbler cylinder mechanism into which the key enters and which the key turns. It houses the pins of a pin tumbler cylinder mechanism.


Privacy set

A lock used on bathroom and bedroom doors having an inside button or turn knob to lock the knob or lever with an emergency function which will unlock the set from the outside.


Pro key

High security patented cylinder system. Operates on 7 pins and has achieved CEN 5.



The stepped shaped reduction or recess cut along the meeting edges of each of a pair of swing doors leaving projections which overlap when the two doors stop on each other at closing.


Rebate Set

Used on overlapping double doors or single doors closing into the frame. The rebate raises the height of the edge of the door to allow the mortise lock to be fitted flush.


Rebated (lock or latch)

A mortise lock or latch with a forend specially shaped to correspond with the shaped meeting edge of the door for which it is intended.


Rectangular padlock

Otherwise referred to as a blocking lock. Usually used on roller shutters or double gates.


Repeat differs

The supply of differs which has been issued previously. Usually associated with Master Keyed suites and where a replacement lock is required to have the same difference as the original.


Reversible latch bolt

On mortise door locks (sash locks) the latch bolt has a bevelled edge. This edge hits the striking plate and closes the door. Depending on whether the door is hinged on the right or left determines which way the bevelled edge of the bolt needs to face. On all Chubb mortise locks, the latch bolt can be reversed.


Rim cylinder

A cylinder which connects to a rim lock through the door, allowing external operation.


Rim lock, Rim latch

A lock or latch which is mounted to the surface of a door, rather than inserted into the edge of a door.


Roller bolt

A spring bolt made in the form of a roller, instead of being bevelled.


Roller lock

On Chubb multipoint locks, stainless steel rollers are available providing a tight weather seal for doors.


Rose (or ring)

A shaped metal disc that surrounds the outer face of the cylinder.


Rounded forend

Used when the mortise for a forend is cut out using automated machinery.


Sash lock

A 2-bolt mortise lock used in conjunction with door handles that operate the latch bolt. Commonly referred to as a door lock.


Sash Window

A 2-piece window comprising of a top and bottom sections which move independently of each other.


Servant key

The change key of one (or more than one if of the same change) lock in a Master Keyed or Grand Master Keyed Suite.



The looped metal locking section of the padlock.


Shoot (of a bolt)

The distance a spring bolt moves under the action of its spring.


Shoot bolts

On Yale multipoint locks – a sintered steel bolt optional extra to secure the head and sill of the door into the frame.



The snib is the mechanism by which the bolt can be held back, (put ‘on the latch’). It can either be a button with slide movement or a push movement.



The part of the door handles usually of square section which passes through the top whole follower in a mortise door lock to operate the spring bolt.


Spring bolt

Sometimes called the latch bolt. A bolt having the outer edge shaped by beveling of the vertical face. A bolt which may be pushed back into the lock-case and will return to the extended position without mechanical assistance.


Sprung shackle padlock

A padlock, the shackle of which springs open when unlocked, and is locked by snapping to.


Stainless steel faceplate

On Yale multipoint locks – the exterior plate to fix the lock in situ within the door.



1.A box-like fitting on the jam of an inward opening door, and into which the bolt or bolts of a rim latch or lock shoot when the door is closed. 2. Part of the hasp and staple for use with a padlock. The padlock shackle passes through the eye or hole in the staple.



Also referred to as the door frame. Commonly there is a standard stile or narrow stile.



A device fixed in or on a door jamb into which the lock or latch bolt engages when the door is closed.


Sub grand master key

A key that will operate all locks in its main group or (sub-grand suite) of a Grand Master Keyed system.


Sub master key

A key that will operate all locks in its own smaller group (or sub-suite) of a Grand Master Keyed system.


Suite (of locks)

A group or collection of locks and/or locking latches and padlocks of different types and changes incorporated together under a Master Key or Grand Master Key.



The distance a deadbolt extends from the case under the actions of its key.


Thumb turn

A small fitting on the cylinder found on the inside of a door that is gripped between thumb and finger to operate the deadbolt. It should not be used on glass or wood-panelled doors. Ideal for fire exit doors where escape is always needed.



Commonly referred to as door furniture.


Tubular mortise lock

One having a tubular-shaped case and requiring bored (round) holes rather than a chiselled rectangular mortise.



A component of a lock or cylinder which prevents operation of the lock mechanism except by insertion of the correct key.

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