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The Locksmith Glossary
ACE LOCK
A high quality lock with pin tumbler chambers arranged
in a circle instead of a straight line as they are in a standard
cylinder. Ace locks use tubular keys and have a shear line parallel
to the face of the lock. The name comes from the trade name of the
most popular lock of this type. Also called tubular lock.
AUXILIARY BOLT
The anti-thrust bolt of a deadlocking latch
which automatically deadlocks the latchbolt when its door is closed.
BAR LOCK
A lock which secures one half of a sliding glass door
or window by insertion of a steel bar horizontally across the nonoperating
door to jam the sliding element of the door against the
door frame.
BOLT
The part of a lock which slides part way out of the lock case
to fasten the lock to its strike, shackle or other restraining member.
BONDED LOCKSMITH
A locksmith who has taken out an insurance
policy to protect his customers financially from his mistakes.
CAM LOCK
A small cylinder lock, usually with disc tumblers,
threaded on the outside circumference of its housing to accept a
matching nut for fastening to a case or drawer, with a relatively large
cam which acts as its bolt. The housing of a cam lock often has a flat
to keep the lock from twisting as the key turns if its nut is loose.
CHANGE KEY
A key which opens and closes only one lock or
a group of locks keyed alike, that is, with the same bittings. Also,
a special key used to release the inner ring of a key change combination
lock when setting the combination. Also, a special key,
inserted from the rear, used to release the detents from the sweeps in
a changeable tumbler safe deposit lock when changing the combination.
CLOSET SPINDLE
A spindle with a turnpiece securely fixed to
one end and room for a door knob at the opposite end, for use on the
inside of closet doors.
COMBINATION
A series of key cuts and a matching series of
tumblers set in a lock to permit opening only with the use of a key
cut to match the series. Also, the sequence of numbers to which the
dial of a combination lock must be turned as a result of the setting of
its tumbler wheels.
DEADLOCKING LATCH
A latch or springbolt with a small antithrust
bar mounted alongside, parallel to the main latch, which resists
forcing. Also called an anti-shim springbolt, a deadlatch or,
occasionally, an anti-pick latch.
DOOR BEVEL
The inside-to-outside angle of the lock edge of
a door. The common bevel for heavy doors—one-eighth of an inch
for every two inches—is needed so that the leading edge of the door
will clear the frame in a close fit. See also lock bevel.
DROP BOTTOM COMBINATION LOCK
A combination lock
in which the lever nose is pushed into the notch of the drive cam
from the bottom of the lock by a counterweight, when the notch and
the nose are lined up.
EQUIVALENT
The reference number, from zero to nine or,
sometimes, from one (through nine) to zero, which stands for the
depth of key cut for a particular key cut for the lock of a given manufacturer.
Also called equivalent bitting depth. Equivalents are found
in code charts. When zero stands for no key cut, the depth of key cut
which the equivalent represents is found by multiplying the bitting
increment by the equivalent number.
EXTRUDED PADLOCK
A padlock in which the case is formed
from some material, usually metal, forced through dies under pressure
while in a heat-softened state.
FENCE
An upright metal pin attached to the bolt of a lever lock,
or to the bolt of a combination lock, which passes through the gates
in the levers when the correct key aligns the lever gates, or into the
gates in the tumblers of a combination lock.
FIXED TUMBLER
A safe deposit lock lever tumbler with an unchangeable
setting. Also called a fixed lever or a non-changeable
lever. While combination tumblers may or may not be fixed tumblers,
guard tumblers and trap tumblers are always fixed tumblers.
GATE
The opening in a lever tumbler which allows the fence to
pass and the bolt to retract when lifted by the correct key so that it
lines up with the fence. The position of the gate on the lever determines
the bitting of the key. Also called the gating or the gateway.
GUARD TUMBLER
A special type of lever tumbler used in safe
deposit locks to prevent opening without use of a guard key with
matching combination. In single horn safe deposit locks there are
usually two guard tumblers mounted on the same curb post as the
other tumblers. In double horn safe deposit locks there are usually
five or six guard tumblers mounted on a separate curb post with key
access through the second horn. The guard tumbler is also called the
preparatory tumbler. See also trap tumbler, combination tumbler.
HOLLOW MILL DRILL BIT
A drill bit shaped with a hollow
in its tip for cutting external cylindrical forms in various materials.
Hollow mill drill bits are used by locksmiths for removing rivets.
HOLLOW POST KEY - Another name for a barrel key.
IMPRESSIONING
A technique of fitting a key to an existing combination in a lock, without taking the lock apart, when no existing
key is available to copy. The method involves binding the
tumblers in their chambers with a turning action on an inserted key
blank so that up and down or in and out movement of the blank will
cause a small mark, called an impression, to appear along the top
edge of the key blade for each of the bound tumblers. The locksmith
files each key cut until impressions stop appearing. No impression
at a key cut indicates that the tumbler has cleared the shear line, is
no longer binding against the wall of the cylinder housing and that,
therefore the key cut is the proper depth. When every key cut is so
filed, the plug will turn and the lock will open.
INTERCHANGEABLECORE CYLINDER
A cylinder, used in
interchangeable core systems, in which the plug and tumblers form
a separate unit, called the core, which is held in place in the cylinder
by a special sleeve, also called the slide, operated by a control key.
Interchangeable core cylinders permit a person to rekey a lock or
a group of locks without special training by simply inserting and
turning the control key, pulling out the old core and putting in a new
core. See also interchangeable core, removable core and removable
core cylinder.
JIMMY
Any tool, such as a short crowbar, to provide leverage for
jimmying open locked doors.
JIMMY-RESISTANT LOCK
A lock with a bolt which moves
up or down into its strike instead of moving in and out of the door
frame, so that prying the door will not release the bolt of the frame.
Also called a jimmy-proof lock.
KEY CHANGE COMBINATION LOCK
A combination lock
for which the combination can be changed by inserting a key into
a special hub to release the inner ring of the wheel. See also key
change wheel and combination lock.
KEY MACHINE
A machine designed for making key cuts. Also
called a duplicator. The standard key machine has a rotating cutting
wheel and a pair of joined, movable vises—one for a sample key
and one for a key blank. The operator guides the sample key in one
vise over an adjustable guide and the key blank in the other vise
automatically passes and is shaped by the cutting wheel. See also
code cutter.
KEYHOLEWARD
A projection into the keyhole of a bit key lock
from the side of the keyhole which prevents a bit key from entering
unless it has a side groove, called a bullet, cut along the bit width.
The keyhole ward is usually part of the metal cover of the lock case.
LATCH GUARD PLATE
A steel plate bolted to a door to cover
the gap between the door and the frame, in the vicinity of the latch
and the strike, to prevent jimmying and loiding.
LEVER
A geared part of a combination lock tumbler wheel in
a key change combination lock which locks the wheel’s setting in
place until the change key is inserted into the hub to release the gears
of the inner ring. Also called the wheel arm. Also, that part of a
combination lock to which the fence is attached and by which the
bolt is retracted after the proper combination has been dialed. Also
called a drop arm. Also, a lever tumbler. Also, the detent or the
sweep of a safe deposit lock changeable tumbler.
LOCKOUT KEY
A special key, formerly used by the management
of a hotel or a rooming house, made by cutting away the bow
and the top half of the key except for the tip which remains intact so
that the lock’s pins will trap the tip of the lockout key and prevent
insertion of any other key. Lockout keys were used against tenants
with unpaid bills.
MAISON KEYING
A system, the reverse of master keying, in
which several keys work one lock, often used on entrance doors to
apartment buildings. In maison keying master pins of many increments
are used to allow many keys to open the same cylinder, with
substantial loss of security.
MASTER PIN
A small pin tumbler, flat on both ends, placed
between the bottom pin and the top pin in a lock’s pin chamber to
allow more than one key to work the lock. The extra pin creates an
extra break between pins which allows a division at the shear line
when the master key is used. Also called a master pin tumbler.
NETTLEFOLDS LOCK
An old style lock with two side bolts
which protrude out of the main bolt near its end and retract into
a hollow in the main bolt during unlocking. The bolt assembly is
sometimes called a fly bolt.
NOSE PULLER
A safe deposit lock tool which uses the mechanical advantage provided by a screw thread to pull the nose out of a
safe deposit lock and thereby breach the lock’s security.
OFFICE FUNCTION LOCK
A lockset in which both knobs
work latchbolt (in some cases outside key and inside knob work
latchbolt); outside key and either inside key or inside turnpiece, if
part of lock, work deadbolt; stop button locks outside knob; inside
knob and outside key release stop button.
OPERATING SHEAR LINE
The primary shear line of an interchangeable
core which controls the rotation of the plug and the
opening of the lock. It is the gap between the plug and the sleeve.
See also control shear line.
PALACE MOTION
An action used in mortise and rim locks in
which the hub works directly against the foot of the bolt and alternately
against a crank so that the bolt will move with approximately
the same ease when the knob is turned in either direction.
PICKING
The manipulation of the tumblers of a lock with small
tools called picks inserted through the keyway so that the tumblers
line up and the lock can be opened. See also raking.
POST
The round section of a bit key between the shoulder and the
tip, from which the bit projects. Also, one of any number of round
projections of a lock case on which lock parts pivot or by which they
are held in place. See curb post.
PUSHBUTTON LOCK
A keyless lock on the combination lock
principle with either combination slides or combination wheels
which move to line up gates when the buttons are depressed in their
correct sequence.
QUADRUPLE BOLT/QUADRUPLE THROW LOCK
A lock
with four bolts, all fully extended by four full turns of its key.
RAKING
A picking technique which entails rapid in and out, up
and down movement of a wave-shaped pick to cause the tumblers of
a lock to bounce to the shear line and catch there as turning pressure
is applied to the plug. Also called jiggling.
REMOVABLE CORE CYLINDER
A cylinder with a removable
core. Although an interchangeable core cylinder, with its unique
control key, is sometimes considered one type of removable core
cylinder, the term is usually limited to those cylinders with removable
cores which are not operated by control keys. See also interchangeable
core, interchangeable core cylinder and removable core.
ROLLER BOLT
A bolt with a roller mounted vertically on the
tip, used on occasion in place of a beveled bolt to reduce friction and
to reduce the danger of injury from the sharp edges of a beveled bolt.
SAFE DEPOSIT LOCK PULLER
A tool which forcibly removes
the door of a safe deposit box, using the mechanical advantage
of a screw thread, when other means of entry are impractical
and after the locksmith has tried to open the door by pulling only the
nose of the lock.
SECTIONAL MASTER KEYING
A method of master keying
by using the same combinations with a number of different key sections
chosen in such a way that higher level master keys will fit into
the keyways of lower level master keys and their change keys, but
not vice versa.
SHUTTER
The spring-loaded part of a dust cap on an automobile
door or trunk lock which actually covers the keyhole and which is
pushed out of the way when the key is inserted. See also keyway
shutter.
SPANNER WRENCH
A wrench used with round nuts and other
nuts which a standard wrench will not grip. Spanner wrenches are
usually made out of two pieces of steel, pivoted at one end for adjustment,
with pins at the other end of each arm which fit into holes
in the nut to permit tightening and loosening. Spanner wrenches are
sometimes a single piece of steel shaped like a half circle with a hook
bent into one end to catch a notch in the nut and a handle shaped out
of the other end.
SYMBOL
One of the sets of letters and numbers used on keys
and cylinders in master key systems to tell the user the exact function
of the key or cylinder in the system. Also called a key symbol.
See key set. For example, M - master, GM - grand master, GGM
- great grand master. Master keys often carry two letters, one to
identify their grand master, the other to identify their series of locks.
The symbol A is often used for a grand master key, with AA, AB,
AC, etc., representing master keys controlled by A. Change keys
would then be AAI, AA2, etc., and ABI, AB2, etc., and so on. Another
grand master key in the same system would be designated B,
a third would be C, and so on. The prefix X on a cylinder indicates
crosskeying. Some other symbols are SKD–single keyed different
(not opened by master keys), KA–keyed alike.
TENSION WRENCH
An L-shaped tool made of spring steel
strip, used in picking locks to apply pressure to the cylinder plug
while manipulating the pins to the shear line. Also called a turning
wrench.
TIME LOCK
A special lock used on large safes and bank vaults
with a heavy bolt which blocks the main bolts of the safe or vault.
When the time lock is on guard (that is, when it is locked), no one can
open the door, even with the correct combinations and keys, short
of destroying the door, until the specified time set on the lock has
elapsed. Time locks usually have at least two clock mechanisms to
prevent lockout in case one of them should break down.
TOP PIN SEATER
A pair of pin tumbler tweezers with an Lshaped
piece of wire positioned above the dual hollows near the tips
of each prong for pushing pin tumblers, especially top pins, into
place in their chambers.
UNASSOCIATEDMASTER KEY
A special master key in a specially
designed multi-level master key system which is set to operate
locks anywhere in the system without cross-keying. An unassociated
master key can have special changes connected with it which
are independent of the rest of the system. Akin to selective master
keys.
UTILITY LOCK
A small cylinder lock, usually used on metal
cabinets, chests and drawers, with a cam in the rear to act directly as
a bolt and with a flat area on at least one side of the housing to keep
the cylinder from turning in its mounting hole.
VAULT LOCK WHEEL PACK
A set of wheels, flies, tension
washers and a wheel bridge, which allows for right-hand (RH),
left-hand (LH), and locked-on-by-combination (LOBC) combination
changes for a vault combination lock. See wheel pack.
VERNIER SCALE
A short scale, named after the sixteenth century
French mathematician Pierre Vernier, designed to slide along
the divisions of a graduated instrument, such as a caliper, so that
parts of the division are determined by observing which line of the
short scale coincides with a line of the larger scale.
WAFER TUMBLER
One of the eight special disc tumblers used
in the plug of a popular cylindrical lockset made by the Schlage Lock
Co. There are three series wafers, four combination wafers and one
master wafer in each such lock, under normal conditions. The series
and the combination wafers can be changed to any of fourteen positions
in seven slots for different combinations. See also combination
wafer, master wafer and series wafer. The name, wafer tumbler, is
sometimes used indiscriminately to refer to the disc tumbler in general.
WING
Another name for the bit of a bit key. Also, one of two projections
on a metal plate attached to a night latch thumb turn which
serves to retract the latch when the thumb turn is turned. Also, one
of two projections on a metal plate which transfers the motion of the
connecting bar through the night latch back plate to retract the latch
when the key is turned. Wings are similar in function to the horns of
a hub.
WROUGHT CASE PADLOCK
A padlock with a body formed
by rolling, hammering or drawing a sheet of metal.
YOKE
That part of a mortise lockset which connects the knob to
the latchbolt. Also, a part in certain mortise locksets which enables
a single set screw to secure either two cylinders or one cylinder and
a thumb turn at the same time.
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