Glossary - L

laminated padlock (np)
padlock in which the body is constructed entirely of flat metal plates, riveted together in the form of a pack

latch (n)
self-engaging fastener which secures the leaf of a door or window in the closed position, and which can be released by hand (see also EN 12209 & prEN 14648)

latch action (np)
arrangement of parts that operate a latch bolt (see also EN 12209 & WI 33/250)

latch bolt (np)
bolt¹ which, by virtue of its shape and the forces acting on it, engages automatically with the locking plate as the door is closed (see also EN 12209 & WI 33/250)

latch control (np)
(Product specific term - see EN 1154)

latchplate (n)
(Product specific term - see EN 1906)

latchset (n)
latch, complete with associated door furniture, spindle and fixings

latent friction (np)
friction due to tight hinges and/or badly fitting door

lateral pick up (np)
condition where one or more key steps lift the wrong lever(s)

lath (n)
(see "bolt tail")

leading edge safety device (np)
(Product specific term - see prEN 12650)

leading face (np)
(Product specific term - see prEN 12650)

leading mullion (np)
(Product specific term - see prEN 12650)

leading mullion safety (np)
(Product specific term - see prEN 12650)

leading stile (np)
stile on the locking side

leaf (n); pl: leaves
movable part of a door or window (see also prEN 12650)

left hand door (np)
door which opens in a clockwise direction when viewed from above

left hand sliding door (np)
sliding door of a single sliding door assembly which moves left to open when viewed from the sliding door side

left hand swing door (np)
swing door which opens in a clockwise direction when viewed from above

letter plate (np)
framed rectangular aperture with at least one flap, for fixing to a door leaf or wall, to enable essentially flat items of mail to be passed through

lever ¹ (n)
pivoting form of detaining element that is positioned by the key as it rotates

lever ² / lever handle (n/np)
handle in the form of a pivoting arm. (see also EN 179)

lever action bolt (np)
bolt ² in which the movement of the shoot ² is controlled by a lever ²

lever mechanism (np)
lock mechanism comprising one or more levers ¹

lever pivot (np)
stump in a lockcase about which the levers ¹ rotate

lift / lift height (n/np)
distance (or angle) a particular detaining element has to move from its "rest" position to the unlocking position, normally denoted by a number - e.g. No.1 lift, No.2 lift etc where No.1 is the highest lift

lift increment / interval (np/n)
distance (or angle) between adjacent lifts

lift up latch (np)
(see "Suffolk latch")

lift-off hinge (np)
single-axis hinge, the two halves of which can be separated in the axial direction (see also EN 1935)

light (n)
glazed part of a window

light reflectance value (LRV) (np)
measured level of reflectivity of a surface under specified conditions

light sliding door, top hanging (np)
door with a leaf of less than 100 kg mass, suspended from a top track and having a bottom guide (see also EN 1527)

limiting device (np)
(Product specific term - see prEN 12650)

limiting stay (np)
rigid arm device that can be used to prevent a door from opening too far and causing damage

linear compression force (np)
(Product specific term - see EN 12365)

lining (n)
plate fixed to a component to reinforce it or fill up a space

lintel (n)
horizontal crosspiece over a door or window for the purpose of taking load (see also prEN 12650)

live bolt (np)
(see "spring bolt")

lock (n)
device for securing a door or window in the closed position, where unlocking movement of the bolt¹ is by means of a differ key from at least one side. (see also EN 12209 & WI 33/250)

lock assembly (np)
lock, together with the associated components that are needed to enable it to perform the locking function

lock case ¹ (np)
part of a lock that houses the locking mechanism (see also EN 12209 & WI 33/250)

lock case ² np)
cylinder mortice lock without the cylinder

lock cylinder (np)
(see "cylinder")

locking bar (np)
bar for securing a door leaf in the closed position, or for securing two doors together, using a padlock

locking box / striker box (np)
rigid enclosure behind the bolt aperture(s) of a locking plate

locking element (np)
(Product specific term - see prEN 13633 & prEN 13637)

locking latch (np)
latch capable of being locked

locking mechanism (np)
arrangement of components that provide the locking function (see also EN 12209, WI 33/250 & EN 12320)

locking plate (np)
generally accepted term for any component that engages the bolt or bolts of a lock (i.e. it includes striking plate, keep and staple) (see also EN 12209 & WI 33/250)

locking point (np)
point of interaction between a locking bolt¹ (or any combination of locking bolts that are less than 150mm apart and move in the same direction) and the associated locking plate(s). (see also WI 33/250)

locking snib (np)
hand operated device for preventing a bolt from being thrown or withdrawn, or to change the function of a lock or latch without dismantling (see also EN 12209 & EN 1906)

lockplate - cylinder (np)
(Product specific term - see EN 1906)

lockplate - lever (np)
(Product specific term - see EN 1906)

locks to pass (adj)
(see "keyed alike")

lockset (n)
lock, complete with associated door furniture, spindle and fixings

London strip (np)
steel bar fitted down inside of door frame to provide additional support for locking plate when subject to force attack

loose pin hinge / loose pin butt (np)
butt hinge with removable hinge pin

low energy powered swing door (np)
(Product specific term - see prEN 12650)