glossary of terms

Automatic Deadlocking
This is on a latch that prevents the tongue from pushing back while the door is still closed

Backplate
This is the plate on which the parts of a handle or knob are mounted.

Backset
This is the the distance from the edge of the door to the centre of the keyhole or handle.

Bathroom Lock
This is a lock fitted to any internal door which has either a spring latch operated by a handle or knob from either side, or  a privacy bolt operated by a small thumb turn.

Bathroom furniture
These are lever handles mounted on plates fitted with a thumb-turn inside to operate a bathroom lock.  They are available in all styles to match the door furniture selected.  The outside plates incorporate a release device in order to allow the thumb-turn to be operated in an emergency.  These are sometimes ‘handed’, i.e., right or left hand fixed because the inside and outside plates differ, therefore it is essential to determine which ‘hand’ is required.  Some have coloured ‘indicator’ panels to designate whether occupied or not.  Care must be taken to identify the make of bathroom lock to be used and, thus, the correct size of spindle,i.e., 5 mm or 8 mm.

A similar pattern is the ‘lockable lever’ where turning the snib activates a mechanism behind the plate which in turn ‘locks’ the lever handle.  This type is used with a standard mortice latch thereby eliminating the need for a bathroom lock.  They are considered unsuitable for commercial applications.

When round rose furniture is used with a bathroom/privacy lock the thumb-turn and indicator with emergency release is on a separate rose which should suite with the lever rose.

Cabinet Lock
This is a term for a lock of any type used on furniture, such as cupboards, chests, drawers and boxes.

Case
This is the metal body of a lock or latch housing the mechanism.

Centres
This is the distance between the centre of the keyhole and the hole for the handle spindle.
 
Deadlatch
This is a latch, either rim type or mortice type, which secures the door closed, but can be withdrawn by key from outside and by knob or handle from inside. Latch tongue cannot be pushed back (credit card trick) once the door is shut. See also Nightlatch

Deadlock
This is a standard mortice lock, which is set into the edge of a door that has a square-ended bolt operated by key or sometimes by a thumb turn on the inside.

Deadlocking
This facility in a rim lock which, using an extra key turn on the outside, stops the latch or bolt from operating when the door is.

Escutcheon
This is the surround plate for a keyhole.
 
Forend
This is the face of the lock or a latch which is seen on the door edge, through which the bolt or latch tongue protrudes.

Hand
This is the direction of opening a door and will show which way the bevelled latch must slope in order to operate.

Keep
This term is used for the striking plate fitted to the door frame which takes the lock bolt or latch tongue.

Knob Furniture
Knob furniture should be used with horizontal rim or mortice locks (or latches).  If used with upright sash locks the follower (spindle hole) must be set well away from the edge of the door.  The minimum back-set recommended is 80 mm.  This is to avoid injury to the hand when opening and closing, particularly on the side of the door that has a stop on the frame.
If an upright mortice lock or latch is specified, the action (operation of the follower) must be two way and fitted with a light spring.

A wide variety of shapes and sizes of knob are available, as part of a suite or an individual design.

Latch
This is a spring-loaded tongue which secures the door closed. Some types  of latch have now been adapted to lock as well

Lever
This is the part inside the lock which is moved by the key. It allows the lock to be operated. Usually, more levers means higher security. Most insurance companies now require a 5 lever lock to be fitted to all external doors.

Lever Handle
This is a horizontal handle for operating the latch mechanism. These handles are usually spring-loaded to ensure the return to the horizontal position after use.
Lever handles may be preferred to knobs where the door is constantly used by people passing through with their hands full, i.e. an office door.  It is comparatively easy to depress the lever with an e bow and push a door when it opens away from you.

Lever handles for architectural work should be functional, well proportioned and of simple clean-cut lines, except where ‘period styling’ is required.
The levers should be of good size providing a satisfactory grip, but the projection should not be excessive.  In busy premises such as schools, restaurants, hotels and hospitals where users are likely to pass close to a door, lever handles which return to the face of the door are more appropriate for safety reasons.

Mortice
This is a recess cut into the edge of a door to receive a mortice lock or latch.
A set of mortice lock furniture comprises a pair of levers to knobs on roses with two escutcheons, or back-plates with keyway, spindle and surface or through fixings.

A set of mortice latch furniture comprises a pair of levers or knobs, spindle and fixings as above but without key escutcheons or keyway.  In the case of back-plates.

Nightlatch
This is a latch, either mortice or rim type, which will secure the door closed. It can be withdrawn by key from the outside and by a knob or handle from the inside. It has a 'snib' to hold the latch back if required. This type of latch is not very secure and can be opened from the inside unless either deadlocked from the outside or using a locking handle on the inside. 

Pin Tumbler Lock
This type of cylinder mechanism is found on most types of rim lock. The cylinder has a line of small pins which, when the key lifts the pins to the correct position, allows the cylinder to turn. When the cylinder is turned the lock is operated.

Rim Lock or Latch
This refers to locks or latches which are fitted on to the inside face / edge of a door.

A set of rim lock furniture consists of a pair of levers or knobs, one attached rose and spindle plus one escutcheon.  The lever/knob and rose will be fitted to the outside – opposite side to the rim lock.

A set of rim latch furniture is similar to rim lock except that the escutcheon is not required.

Roller Bolt
This is found in some latches rather than a spring loaded tongue. It is a bolt made with rollers to engage into the latchplate.

Rose
This is a circular plate on which the handle or knob are mounted.

Sashlock
This is a mortice lock containing a latch operated by handles and a bolt secured by a key.

Snib
This is a small button or switch on the case of a nightlatch which is used to hold the latch tongue back or to stop the latch being operated when closed.

Spindle
This is a square bar inserted through a latch which connects the handles on either side of the door.

Striking Plate (latchplate)
This is a plate fixed to the door frame with one or more bolt holes, into which the bolt or latch shoots.

Sprung and unsprung furniture
Non-sprung furniture is commonly used and works well, providing suitable locks or latches are used with heavy duty springing.  Non-sprung roses and back-plates are usually 5 mm thick or less.  Spring-loaded roses are generally 9 or 10 mm.  Flat plate back-plates are available with a spring cassette on the back but the doors must be a minimum of 45 mm thick to accommodate the recesses.

Many levers are spring loaded in order that they remain in the horizontal position when not is use.  This is quite independent of the spring action in the lock/latch.  Various methods are used, some expansion springs, other compression.  The majority are effective, but it is a distinct advantage to select a type fitted with a spring which is replaceable.  The majority of spring loaded lever handles are single handed, with a stop built in to limit the travel of the spring and the handle.