theoretical key changes n. pl. the total possible
number of different combinations available for
a specific cylinder or lock mechanism
three column progression n. a process wherein key
bittings are obtained by using the cut possibilities
in three columns of the key bitting array
three pin master key n. a master key for all
combinations obtained by progressing three
bitting positions
three point latch n. a self-latching device designed
to latch a door at the top, bottom and edge
throw member n. an intermediate actuator which
engages the rear of the plug to transfer motion to
a cam, tailpiece or other actuator
tip n. the portion of the key which enters the
keyway first
tip stop n. a type of stop located at or near the tip
of the key
TMK abb. top master key
toe (of a shackle) n. that part of the shackle,
which may be removed from the padlock body
tolerance n. the deviation allowed from a given
dimension
top master key n. the highest level master key in
a master key system
top of blade n. the bitted edge of a single bitted key
top pin n. usually a cylindrical shaped tumbler,
usually flat on both ends and installed directly under
the spring in the pin stack
total position progression n. a process used to
obtain key bittings in a master key system wherein
bittings of change keys differ from those of the top
master key in all bitting positions
try-out key n. a manipulation key which is usually
part of a set, used for a specific series, keyway,
and/or brand of lock
tubular key n. a key with a tubular blade. The key
cuts are made into the end of the blade, around its
circumference.
tubular key cylinder n. a cylinder whose tumblers
are arranged in a circle and which is operated by
a tubular key
tumbler n. a movable obstruction of varying size
and configuration in a lock or cylinder which makes
direct contact with the key or another tumbler
and prevents an incorrect key or torque device from
activating the lock or other mechanism
tumbler spring n. any spring which acts directly
on a tumbler
two column progression n. a process wherein key
bittings are obtained by using the cut possibilities
in two columns of the key bitting array
two pin master key n. a master key for all
combinations obtained by progressing two bitting
positions
two-step progression n. a progression using
a two increment difference between bittings of
a given position
-U-
UL abb. Underwriters Laboratories
UL listed adj. listed in a directory as having passed
specific Underwriters Laboratories testing
unassociated change key n. a change key which is
not related directly to a particular master key through
the use of certain constant cuts
unassociated master key n. a master key which
does not have change keys related to its combination
through the use of constant cuts
uncombinated adj. 1. of or pertaining to a cylinder
which is or is to be supplied without keys,
tumblers and springs 2. of or pertaining to a lock,
cylinder or key in which the combination has not
been set
uncontrolled cross keying n. a condition in which
two or more different keys under different higher
level keys operate one cylinder by design; e.g.,
XAA1 operated by AB, AB1. Note: This condition
severely limits the security of the cylinder and the
maximum expansion of the system, and often leads
to key interchange.
unidirectional cylinder n. a cylinder whose key can
turn in only one direction from the key pull position
-V-
vertical group master key n. the two-pin master
key for all combinations listed in all blocks in a line
down a page in the standard progression format
VGM abb. vertical group master key
visual key control n. a specification that all keys
and the visible portion of the front of all lock
cylinders be stamped with standard keying symbols
VKC abb. visual key control
-W-
ward n. a usually stationary obstruction in a lock
or cylinder which prevents the entry and/or operation
of an incorrect key
ward cut n. a modification of a key which allows
it to bypass a ward
warded adj. having one or more wards
-X-
X sym. symbol used in hardware schedules to
indicate a cross-keyed condition for a particular
cylinder; e.g., XAA2, XlX (but not AX7)
-Z-
zero bitted adj. of or pertaining to a cylinder
which is or is to be combinated to keys cut to the
manufacturer's reference number "0" bitting
Terminology
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