Active Leaf:
In a pair of doors, the door or doors in which the latching device is installed; also referred to as an Active Door.
All-section Key Blank:
The key section that enters all the keyways of a multiplex key system.
ALOA:
Associated Locksmiths of America, Inc.
Alternating Parity:
Most often describes the type of mathematical progression employed to develop master key systems. Parity refers to the bitting depths, “odd” or “even” numbers. In an alternating parity system, the bitting depths in any given bitting position can be odd or even numbered depths; sometimes called a “one-step” system.
Americans with Disabilities Act:
This is a US federal law dealing with minimum standards of building accessibility, as well as other issues affecting individuals with disabilities.
Annunciator:
A device that produces an audible and/or visible indication of light and/or noise, or a verbal message.
Anti-friction Latch:
A device incorporated into the latch bolt of a lock for reducing friction between bolt and strike.
Anti-Passback:
A security feature in electronic access control systems that prevents a card or token from being used to enter an area a second time without first exiting, ensuring proper tracking of individuals through controlled areas.
Anti-thrust bolt:
A spring bolt, for a night latch particularly, which cannot be pushed back when it has shot out and fastened a door, although it can be withdrawn by knob or key. This security device is usually achieved by a dog inside the latch case which falls behind the bolt and keeps it shot out when an auxiliary slide is pushed in.
Anti-thrust plate:
An overlapping metal plate fitted to outward opening doors so as to prevent access to lock bolts.
Astragal (Overlapping):
A vertical moulding that extends the full height of the door leaf and is applied to a door or pair of doors at their meeting edges. The astragal closes the clearance gap for the purpose of providing a weather seal, minimizing the passage of light between the doors, retarding the passage of smoke and flame during a fire, or maintaining security. Some types of astragals are flat pieces of aluminum, steel, or wood. Some astragals are designed to wrap around the lock stile of the door. Overlapping astragals are not permitted to be used on pairs of doors that are required to swing in the direction of egress travel.
Astragal (Overlapping & Interlocking):
A set of vertical mouldings that extend the full height of the door and is fastened to a door and jamb or a pair of doors that interlock for increased security from a forced entry attack.
Astragal (Split):
A vertical molding attached to the meeting edges of each of the leaves of a pair of doors, for protection against weather. The split feature permits both leaves to be active. Split astragals can be surface-mounted, semi-mortised or full-mortised in the vertical edge of the doors. Split astragals are available with brush, pile, silicone, neoprene, or vinyl inserts to seal the gap between the meeting stiles in pairs of doors.
Automatic Deadlatch:
A deadlatch, the main bolt of which is automatically locked (or deadlocked) when the door is closed.
Back Check:
The resistance provided by a door closer as the door is opened.
Backplate:
The plate, fixed on a door, to which the moving parts of a lock or latch are attached.
Backset:
The horizontal distance from the outside face of the outer forend to the centre of the keyhole or follower hole (or both). Designated as the “keyhole backset” or “follower backset”.
Barrel Bolt:
The common kind of door bolt having a round shoot running in a long continuous guide or strap attached by the backplate, the shoot being provided with a knob or the equivalent for operation by hand.
Barrier-free:
Refers to ensuring accessibility for seniors and people with disabilities.
Bell Crank:
A mechanical device using a pivoting action to change the direction of a mechanical force or motion.
Bevel (of a door):
The pitch on the leading edge of a door that allows clearance for closing.
Bevel (of a lock):
The pitch of the face designed to match the bevel of a door. Some locks have an adjustable bevel.
Bezel:
A threaded collar commonly used to secure certain cylinder or lock assemblies.
BHMA:
(abbr.) Builders Hardware Manufacturers’ Association
Bible:
The portion of the cylinder shell that normally houses the pin chambers, especially those of key-in-knob cylinders or certain rim cylinders.
Binary-type Cylinder or Lock:
A cylinder or lock with a combination that only allows for two bitting possibilities in each position.
Bit:
The part of the key that serves as the blade; usually for use in a warded or lever tumbler lock.
Bit Key:
A key with one or more projecting bits.
Bitting:
The number(s) that represent(s) the dimensions of the key cuts OR the actual cut(s) or combination of the key.
Bolt:
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, striking plate, link, shackle or other members.
Bolt Stump:
A rectangular part in lever tumbler locks located above the talon, passing through the slot in the levers as the bolt moves.
Bow (of a key):
That part of the key which is held in the fingers when operating the lock or latch.
Birmingham Bar:
A steel bar fitted to the inside face of a door frame on the hinge side.
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.
Cam:
Usually a tongue fixed to the end of the plug of a cylinder lock or latch.
Cam Lock:
A complete locking assembly in the form of a cylinder whose cam is the actual locking bolt.
Casement Door:
A hinged door or pair of doors almost wholly glazed; often called a French Window.
Casement Window:
A window in which one or more lights are hinged to open.
Change Key:
A change key which is related directly to particular master key(s) through the use of constant cuts.
Closed Shackle Padlock:
A padlock, the body of which is built up so that the minimum amount of shackle is visible when locked. It offers improved security against forcing or use of bolt-croppers.
Combination Lock:
An abbreviation of a name for a keyless combination lock. Cut cabinet lock A cupboard or drawer lock, the flange of which is recessed into the edge of the drawer or door.
Cylinder:
Usually the cylinder with an inner co-axial plug which houses the pins, top pins (drivers), or disc tumblers and springs in the cylinder body.
Cylinder Housing:
With all component parts removed, this forms the main body or housing of a cylinder.
Deadbolt:
The square-ended bolt of a lock which is moved in both the locking and unlocking directions by the key (but occasionally by thumb turn inside only) to provide fastening. N.B. For obvious reasons, it is inadvisable to incorporate the thumb turn with the deadbolt of any deadlock or lock which is supposed to offer good security, if used on glass or wood panelled doors.
Deadlatch:
A nightlatch or latch, the springbolt of which can be locked (or deadlocked) by key or other means.
Deadlock:
A lock having only a square-ended deadbolt operable from one or both sides by key, and occasionally from outside only by key, inside by thumb turn. Sometimes operable only from outside and with no inside keyhole, which is designated a single-entry deadlock.
Detainer:
1. A generic term, not widely used, for any part such as a lever or tumbler which keeps a lock bolt in position 2. The name of the sliding security members in Butter’s System locks.
Differs:
An abbreviation of “different combinations” or changes.
Disc Tumblers:
The small shaped discs (usually of metal) in the disc tumbler mechanism which are the means of providing different combinations.
Door Closer:
A device for closing a door or gate automatically after opening. There are numerous types available.
Door Viewer:
Optical device fitted through a door to enable observation without opening the door.
Double Bitted Key:
One with a bit on each side of the shank.
Double-handed Lock:
1. A lock designed for use either as a right or left-hand installation without alteration, generally by turning upside down. The keyhole has a circular formation at each end of the slot to accept the shank of the key. 2. A cupboard lock, the bolt of which can be shot either way to protrude from either side of the case.
Escutcheon:
The cover for the keyhole of a mortise or similar lock.
Face Plate:
The outer of a double forend. A strip of metal fixed to the inner forend, thus forming a double forend.
Final Exit Door:
The exit door through which entry must later be obtained, and so cannot be bolted. It is usually the front entrance door or final means of exiting.
Flush Bolt:
A door bolt which can be recessed flush into the edge or face of a door.
Hasp and Staple:
A fastening in two pieces for a door or box to be secured by a padlock. The hinged part is called the hasp which is fitted to the door or lid of a box and shuts over the staple, which is on the door frame (or other leaf of a pair of doors) or the body of the box. For real security it is essential to use a hasp and staple with concealed fixing, i.e. the heads of the fixing screws are completely covered when the padlock is locked in position, as otherwise the fitment can easily be removed by withdrawing the screws affording nil security.
Hinge Bolts:
Fixed steel protrusions fitted into the rear edge or hinge side of doors, closing into holes cut into the door frame, to protect from a forced attack on the hinge side of the door.
Hook Bolt:
A pivoted spring-bolt, the head of which is shaped in the form of a hook. Such locks or latches are usually fixed on sliding doors.
Jamb:
The vertical member of a door or window frame. In some areas, the top rail of a door frame is referred to as the top jamb.
Key Steps or Key Depths:
This term usually means the bolt step and lever steps of a key for a lever lock.
Latch:
The type of product with one bolt only, the bevelled springbolt or roller bolt, to latch or fasten the door, but not capable of being locked. Certain types, e.g. locking latches, nightlatches, or deadlatches, can, however, be locked by key or other means.
Lever:
A flat shaped movable detainer in a lock, usually for the purpose of providing security and differs. The lever(s) in a lock have to be actually moved by the key to operate the lock. The belly of the lever is cut away to various depths to provide different combinations.
Lever Mechanism:
A lock mechanism having, as its principle feature, one or more levers.
Lever and Warded Mechanism:
The lever mechanism with the addition of wards, usually for providing a greater number of differs. The addition of wards does not, however, increase the security of a lock. See “Wards”.
Lever Handle:
A piece of lock or latch furniture, usually on a rose or plate, for use as an alternative to a knob for operating the springbolt of a lock or latch. All British lever handles are spring-loaded to ensure the return to horizontal after use, but Continental lever handles are not usually spring-loaded and thus when used with British locks or latches, sometimes tend to sag below the horizontal after a comparatively short period of use, unless additional springing is included in the lock action.
Lock:
A device operated usually, but not always, by a key, having one or more bolts or other members to fasten and secure a door, lid, drawer or other member.
Lockable Bolt:
A bolt that can be shot and locked in position by the use of a removable key.
Locking Latch:
A latch with a bevelled springbolt or roller bolt which is capable of being locked or secured, usually by key.
Lockset:
A lock complete with necessary furniture including a spindle, ready for fixing to the door.
Lockset Furniture or Lock Furniture:
A lockset, minus the lock.
London Strip:
A steel bar fitted to the inside face of a door frame, shaped to accommodate the staple or striker of a rim latch lock.
Long Shackle (LS):
A padlock shackle with a greater amount of clearance than the normal standard shackle.
Lubrication:
On no account should oil be used to lubricate pin-tumbler cylinders. Graphite is the conventional lubricant for this mechanism.
Master Key:
A master key that has particular change keys related directly to its combination via the use of constant cuts.
Master Keyed (Locks or Latches):
A lock or latch capable of being operated also by a master key as well as its own change or servant key.
Mortise:
A hole cut into the thickness of one edge of a door to receive a mortise lock or latch.
Mortise Key:
A key to operate a lever lock, consisting of a bow, shank and bit.
Mortise Lock (or Latch):
A lock or latch which is mortised or let into the thickness of the door from the meeting edge and held in position by screws.
Nightlatch:
A rim or mortise latch with a bevelled springbolt 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-sided Lock (Single-entry):
A lock which has a keyhole on one side only, so that it can be operated by key from one side only, usually outside, but not from both. Nearly all cabinet locks and all padlocks are examples. Some high quality cylinder mortise locks are one-sided.
One-way Action:
An action where the follower will turn only one way.
Padlock:
A comparatively small removable and portable locking device, usually but not always key operated on one side only. The locking member is a circular hinged sliding or swivelled shackle which passes through a hole in a staple, locking bar or similar member.
Panel Grilles:
Steel grilles made to size with various infills of expanded diamond mesh, square weld mesh or fancy infills, usually fitted internally.
Plug:
The part of the pin-tumbler cylinder mechanism or disc tumbler cylinder mechanism into which the key enters and which the key turns. It houses the pins of a pin tumbler cylinder mechanism or the discs and springs of a disc tumbler cylinder mechanism.
Rack Bolt:
A bolt, usually a door bolt, which is toothed so that it may be operated by a pinion.
Rebate:
The measurement of the stepped reduction or recess in the forend of a rebated lock.
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. See “Full Rebated”.
Release:
A striker in various forms to replace the lock strike and is operated electronically.
Rigid Grilles:
Heavy duty, welded construction, rod or bar grilles, usually fitted externally or internally to the fabric of a building.
Rim Cylinder:
This relates to a pack which usually comprises the cylinder with plug, rose, connecting bar, two connecting screws and two keys.
Rim Lock or Latch:
A lock or latch that is fitted by screwing on to the inside face of the door.
Sash Lock:
An upright mortise lock, consisting of a latch bolt and a key operated bolt.
Sash Ward:
Used in rim and mortise locks, alone or in conjunction with levers for the purpose of obtaining or increasing the differs. Formed pieces of concentric metal are affixed around the inside of the keyhole. It also serves as a keyhole bush. The bitted key passes over these wards to operate the bolt. Little security is given when sash wards are used by themselves. See “Skeleton Keys”.
Shackle:
The hinged, sliding or swivelling loop shaped member of a padlock. The heel of the shackle remains always in the padlock body and the toe of the shackle comes out when unlocked. A double locking padlock gives the greatest security against forcing because there are two separate bolts locking outwards in opposite directions, one into a niche in the heel of the shackle, and the other into the toe of the shackle. This is sometimes called heel and toe locking.
Shear Line:
The term is used to denote the line of the circumference of the plug in the bore of a pin tumbler cylinder.
Side Wards:
Notches cut into the sides of bitted keys so fashioned to enable the key to turn.
Sliding Grilles:
Steel sliding grille gates in single or double leaf, running on top and bottom guide tracks, locked by padlock or integral lock.
Sliding Lever:
A lever which slides between or on guides instead of swinging on a pivot.
Spindle:
That part of the door furniture usually of square section which passes through the follower hole and is fitted to the knob(s) or lever handle(s) to operate the springbolt.
Spring Shackle Padlock:
A padlock, the shackle of which springs open when unlocked, and is locked by snapping to.
Springbolt:
Sometimes called the latchbolt. A bolt having the outer edge shaped by bevelling of the vertical face. It is a bolt which may be pushed back into the lock-case and will return to the extended position without mechanical assistance.
Staple:
1. A box-like fitting on the jamb of an inward opening door, and into which the bolt or bolts of a rim latch or lock shoot when door is closed. (It is sometimes referred to in Scotland and the North of England as a Bosshead). Some staples are lipped to act as a guide for the springbolt. 2. Part of a hasp and staple for use with a padlock. The padlock shackle passes through the eye or hole in the staple.
Stop Knob (Snib):
A device incorporated in some latches and locking latches to hold the bolt retracted or deadlock the bolt when door is closed.
Striking Plate:
Sometimes referred to as a “striker”. It is a shaped flat metal plate fixed to the door frame or jamb with one or more bolt holes into which the bolt or bolts shoot. There is a shaped projecting lip on one side to guide the springbolt. It is used with all mortise locks or latches, and with rim locks or latches with reversed springbolt on an outward opening door.
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.
Thumb Turn:
A small fitting, on the inside of a mortise lock, which is gripped between thumb and finger to operate the deadbolt. It should not be used on glass- or wood-panelled doors.
Tie Bars:
The horizontal members of a vertical bar grille.
Time Lock:
A clockwork or electric timing device which disallows operation of a lock or the opening of a door on safes or strongrooms.
Wards:
Fixed obstructions inside a lock case to preclude the use of the wrong key, as the key is cut to pass over the wards and operate the lock. They are sometimes used in lever locks to give increased differs. Wards alone give very little security. See “Skeleton Key”.
Warded Lock:
Any lock or padlock, the mechanism of which makes use only of wards. Not recommended, due to the lack of security.