Types of Locks
A lock having a latch bolt or a dead bolt operated by a
key or a thumbturn or both. This lock is often used in addition to another lock,
which may or may not be key operated but which has a latch bolt operated by
knobs or levers.
Bored Dead Latch
(Also called tubular or cylindrical dead latch) A lock fitting round bored
openings in the face and edge of a door and having a dead latch operated by a
key or thumbturn or both.
Bored Dead Lack
(Also called cylindrical or tubular) These are locks or latches fitting round
bored openings in the face and edge of a door. If they are key operated, the
cylinder is contained in the knob and so occasionally one hears them referred to
as "key-in-the-knob-locks." This is imprecise as other types of locks also have
cylinders contained in the knobs. The round hole in the face of the door is
usually 2 1/8 inches in diameter and the hole in the edge of the door is 7/8
inch to 1 inch. When the lock is installed, the face hole contains the lock body
and the edge hole contains the latch bolt.
Dead Bolt Any type of auxiliary lock requiring a key to project or
retract the dead bolt (lock or unlock) from either side.
(Also known by a number of different trade names) A lock having a
separate latch and dead bolt mechanically interconnected and installed in round
bored openings in the face and edge of a door. It is best known for providing
dead bolt security with the life safety feature of simultaneous retraction. When
the dead bolt is projected, a single turn of the inside knob retracts both the
dead bolt and the latch bolt. This simultaneous retraction function is also
available with some functions of mortise locks.
Mortise Dead Latch
An auxiliary lock fitting a cavity prepared in the edge of the door and having a
dead latch operated by a key or thumbturn both. The key or thumbturn engages the
lock through holes prepared in the faces of the door.
Mortise Dead Lock.
An auxiliary lock having a deadbolt instead of a dead latch and otherwise the
same as a mortise dead latch.
A lock fitting a rectangular shaped cavity in the edge of a door. A round hole
in the face of the door receives a spindle to which knobs or levers are attached.
If key operated, a second round hole above the first receives the cylinder(s)
and thumbturn. Some functions use two cylinders which is not a violation of the
codes because the inside knob always operates. Some functions use two cylinders
which sometimes is a violation of codes because the inside key projects a dead
bolt or locks the inside knob which can only be unlocked by key. (This example
of key operation on the inside applies equally to other types of locks and is
mentioned under mortise locks only because it originated with them.)
The distance from the edge of the door to the centerline of the cylinder at the
centerline of the door thickness.
Latch A plunger which, when actuated, automatically locks a projected
latch bolt against return by end pressure.
A lock component having an end which protrudes from or is withdrawn into, the
lock front by action of the lock mechanism. When the door is closed and the dead
bolt thrown, it extends into a hole provided in the strike thus locking the door.
It does not retract with end pressure.
A lock component having a beveled end which projects from the lock
front in an extended position, but may be forced back into the lock case by end
pressure or drawn back by action of the lock mechanism. When the door is closed,
the latch bolt projects into a hole provided in the strike thus holding the door
in a closed position.
BoltA spring actuated latch bolt with a beveled end and incorporating
a plunger which, when depressed, automatically locks the projected latch bolt
against return by end pressure. Also called dead latch.
this publication, a component fastened to the back of a mortise cylinder plug or
mortise cylinder thumbturn. When rotated, it engages the lock mechanism and
either locks or unlocks.
housing of a lock.
The cylindrical subassembly of a lock containing a cylinder plug with keyway and
a cylinder body with tumbler mechanisms.
The portion of a cylinder that surrounds the plug and contains the tumbler
A tubular portion of the cylinder which rotates within the cylinder body when
the correct key is inserted into it and turned.
Material that surrounds the otherwise exposed portion of a cylinder to protect
the cylinder from wrenching, cutting, pulling, or prying.
The portion of a lock that surrounds and retains the cylinder body. It can be a
knob, part of the lock case or other anchoring means.
A plate fastened to the edge of a door through which the bolts pass.
A cylinder where the cylinder head is flush with, or recessed below, the outside
surface of the trim to protect the cylinder from wrenching, cutting, pulling or
plate fastened to the door frame or the inactive leaf of a pair of doors into
which the bolts project.
A strike reinforced in such a way as to strengthen the frame to which it is
A housing used in back of a strike to enclose the bolt openings.
A bar projecting from the back of a rim or bored lock cylinder engaging the lock
mechanism and when rotated by the key or thumbturn either locks or unlocks.
The component that projects or retracts a dead bolt or latch bolt by grasping
with the thumb and fingers and turning. Sometimes called a turnpiece or turn.
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