This is an electronic version of the
printed Imperial Concise Pocket
Guide to Locks.
No part of this document may be
copied or reproduced without the
express permission of Imperial Locks.
© Guardian Lock & Engineering Co. Ltd. 2003
GLOSSARY OF TERMINOLOGY
B AC K S E T
BIT
BLADE
B O LT S T U M P
BOW
B R OAC H I N G
BURR
CAM
CENTRES
COLLAR
CUTS OR BITINGS
CYLINDER
D E A D B O LT
DEADLOCK
DRIVER
EURO PROFILE
FLUTINGS
FOLLOWER
FOREND
G AT I N G
HANDING
K E Y WAY
L AT C H
L AT C H B O LT
LEVER
LEVER CUTS
LIP
MASTER KEY
MORTICE
O VA L P R O F I L E
PIN TUMBLER
PLUG
R E B AT E D
ROLLERS
SASHLOCK
SHANK
SHOULDER
S P R I N G B O LT
SPRINGING
S T R I K I N G P L AT E
THROWER
WA R D I N G
A Concise
Pocket
Guide
to
Locks
Imperial Works, Wednesfield Road, Willenhall,
Tel: +44 (0) 1902 635964 • Fax: +44 (0) 1902 630675
West Midlands WV13 1AL ENGLAND
For full range please refer to catalogue
Tel: +44 (0) 1902 635964 • Fax: +44 (0) 1902 630675
A CONCISE POCKET GUIDE
TO
LOCKS
T E R M I N O L O G Y
L EVER
TYPE KEY
Imperial is the trade name of
Guardian Lock & Engineering Co. Ltd.
Bow
of Willenhall, West Midlands, England.
The company manufacture a wide range of
locks and latches and is a firm of assessed
Collar
Shank
capability to BS EN ISO 9001:2000
recognised internationally as ensuring
quality of product, manufacture and service.
Warding
This pocket guide provides a brief outline of
the types and operations of the most
Bit
Lever Cuts
common lock types available.
A comprehensive catalogue providing full
specification details is available on request.
T E R M I N O L O G Y
C YLINDER
TYPE KEY
Bow
Blade
Flutings
BS EN ISO 9001:2000
Cuts or Bitings
Shoulder
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T E R M I N O L O G Y
M ORTICE
LOCKS
are made for fixing in a hole or mortice cut in a door from
the edge
T E R M I N O L O G Y
T YPICAL U PRIGHT
M ORTICE S ASHLOCK , two bolts with lever mechanism
BASIC LOCK TYPES
Lever
Locks
Euro Profile
Oval Profile
Cylinder Lockcases Cylinder Lockcases
Outer
forend
Bolt Hole
Mortice Sashlock
Mortice Sashlock
Mortice Sashlock
Latchbolt /
Springbolt
Backset
Inner
forend
Piercings for bolt
through fixed
furniture
Follower
Lip
Centres
Mortice Deadlock
Mortice Deadlock
Mortice Deadlock
Deadbolt
Screw fixing hole
Mortice Sliding
Door Lock
Mortice Sliding
Door Lock
Mortice Sliding
Door Lock
Keyhole
Cap screw
Plan view
Case size
Horizontal
Mortice Lock
Horizontal
Mortice Lock
Horizontal
Mortice Lock
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T E R M I N O L O G Y
T YPICAL M ORTICE
D EADLOCK to suit Euro Profile Pin Tumbler Cylinder
Outer
forend
T E R M I N O L O G Y
T YPICAL M ORTICE S LIDING
D OOR L OCK to suit Oval Profile Pin Tumbler Cylinder
Outer
forend
Backset
Backset
Bolt Hole
Bolt Hole
Inner
forend
Cap screw
Deadbolt
Screw fixing hole
Inner
forend
Piercings for bolt
through fixed
furniture
Plan view
Piercing for
Euro Profile
Cylinder
Clawbolt
Cap screw
Screw fixing hole
Plan view
Case size
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Case size
Piercing for
Oval Profile
Cylinder
T E R M I N O L O G Y
T YPICAL H ORIZONTAL
M ORTICE L OCK , two bolts with lever mechanism
T E R M I N O L O G Y
T YPICAL U PRIGHT
B ATHROOM M ORTICE L OCK . From the inside the deadbolt is
operated by a turn or small knob instead of a key
Backset
Bolt Hole
Centres
Bolt Hole
Outer
forend
Inner
forend
Follower
Deadbolt
Outer
forend
Latchbolt /
Springbolt
Backset
Inner
forend
Piercings for bolt
through fixed
furniture
Follower
Lip
Centres
Lip
Latchbolt /
Springbolt
Cap screw
Keyhole
Screw fixing hole
Piercings for bolt
through fixed
furniture
Turn
Follower
Deadbolt
Screw fixing hole
Cap screw
Plan view
Plan view
Case size
Case size
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T E R M I N O L O G Y
T YPICAL M ORTICE L ATCH
T E R M I N O L O G Y
T YPICAL T UBULAR
M ORTICE L ATCH
Outer
forend
Backset
Bolt Hole
Inner
forend
Bolt Hole
Outer
forend
Follower
Backset
Inner
forend
Lip
Lip
Latchbolt /
Springbolt
Screw fixing hole
Cap screw
Piercings for bolt
through fixed
furniture
Latchbolt /
Springbolt
Screw fixing
hole
Cap screw
Plan view
Plan view
Case size
Case size
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Follower
T E R M I N O L O G Y
T E R M I N O L O G Y
L EVER L OCKS
Most commonly such locks are fitted with three or five levers.
By varying the gatings in the levers and with keys cut
correspondingly, locks are made to differ.
When operated by the correct key, the levers are lifted
together so that the gating is aligned with the bolt stump
allowing the bolt to be thrown or withdrawn.
Use of an incorrect key either overlifts or underlifts the levers
so that the bolt stump is obstructed.
— E URO P ROFILE
BASIC TYPES
Thrower
or Cam
Key Section
or Profile
Lever Spring
P IN T UMBLER C YLINDERS
S INGLE
C YLINDER
Bolt Lath
Bolt Stump
UNLOCKED
POSITION
Gating
Body
Key Section
or Profile
Key
Retaining
Screw Hole
Thrower
or Cam
Lever
Pivot
D OUBLE
C YLINDER
Bolt Head
Key Section
or Profile
LEVERS
C O R R E C T LY
LIFTED
Body
Retaining
Screw Hole
Thrower
or Cam
Turn
K EY / T URN
C YLINDER
Body
LOCKED
POSITION
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Turn
Retaining
Screw Hole
T E R M I N O L O G Y
P IN T UMBLER C YLINDERS
— O VAL P ROFILE
BASIC TYPES
Thrower
or Cam
Key Section
or Profile
S INGLE
C YLINDER
Body
Key Section
or Profile
T E R M I N O L O G Y
P IN T UMBLER C YLINDERS .
Euro and oval profile cylinder bodies have through their length
a rotatable plug broached with a keyway. A thrower or cam is
attached to the end of the plug so that when a correct key is
used to turn the plug, the thrower or cam activates the
mechanism of the lockcase to which it is fitted.
The security of a cylinder is provided by means of spring
loaded pin tumblers, commonly five or six, which in simple
form are in two parts known as pins and rollers or drivers.
In a locked condition the rollers or drivers are partly in the
plug and partly in the body thus preventing the plug from
being rotated.
By use of a correctly cut key the pins and rollers are lifted so
that a shear line is achieved between the plug and the body
allowing the plug to be turned by its key.
Retaining
Screw Hole
LOCKED POSITION
Thrower
or Cam
Plug
D OUBLE
Pin
C YLINDER
Key Section
or Profile
Body
Retaining
Screw Hole
Thrower
or Cam
Turn
Burr
Turn
CORRECT
K EY / T URN
C YLINDER
Body
Driver or Roller
Retaining
Screw Hole
Body
Spring
K E Y L I F T I N G P I N S TO
UNLOCKED POSITION
Shear
Line
U N L O C K E D P L U G R OTAT I N G
Key Section
or Broaching
Plug
Pin
Body
Burr
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Driver or Roller
Spring
T E R M I N O L O G Y
R EBATED C OMPONENTS
For use mainly on double doors where one leaf overlaps the
other
T E R M I N O L O G Y
H ANDING
Many locks and latches are easily reversible to suit the most
common ways of opening and closing hinged doors. However,
some have to be made to suit the hand required. It should be
noted that different handing rules apply in some trades and
countries.
F L AT O R P L A I N F O R E N D
L O C K S A N D L AT C H E S
R E B AT E D F O R E N D
L O C K S A N D L AT C H E S
Left Hand
Left Hand
Right Hand
Right Hand
Left Hand Open Out
Left Hand Open Out
Right Hand Open Out
Right Hand Open Out
Striking Plate
Lock Distance
Piece
Forend
Striking Plate
Distance Piece
Depth of rebate 13mm 19mm or 25mm
DOOR
PA I R
OF
DOOR
D O U B L E R E B AT E D D O O R S
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T E R M I N O L O G Y
S PRINGING
Traditionally upright mortice sashlocks and latches
manufactured in England have been made with the springing of
the latchbolt or springbolt sufficient to allow easy and positive
closing. Such locks are designed and intended for use with
lever handle furniture incorporating it’s own springing, to
return the handle to the horizontal at rest position.
Where upright mortice sashlocks and latches are to be used
with unsprung lever handle furniture, compatibility should be
ascertained and where appropriate locks and latches specified
with heavy springing to suit such applications.
Horizontal mortice locks and latches are primarily intended for
use with knob furniture. Such furniture being self centreing
negates the need for heavy springing. Such locks and latches
are most usually fitted with two way action followers thus
allowing the knobs to be turned in either direction to withdraw
the latchbolt or springbolt.
T E R M I N O L O G Y
R OUND E NDED OR R ADIUS
F ORENDS . Locks and latches having forends and / or striking
plates rounded at the top and bottom may be found
convenient, particularly where factory morticed doors are used.
T E R M I N O L O G Y
T HIEF R ESISTANT L OCKS
By implication all Locks are to some degree resistant to
unauthorised operation. BS3621:1998 is a standard prepared
under the direction of the Building Hardware Standards
Committee for Locks providing an enhanced degree of security
against attack. They may most frequently be required to be
fitted to final exit doors of domestic and some commercial
buildings.
Locks independently tested and assessed to the stringent
requirements of this British Standard carry the Kitemark, the
number of the Standard ie: BS3621 and the name, trade mark
or other means of identification of the manufacturer.
T E R M I N O L O G Y
TO PASS
A set of two locks or more keyed alike so that all are operated
by the same key.
T E R M I N O L O G Y
M ASTER K EYING
As a matter of convenience it is sometimes a requirement that
a number of locks to differ in addition to being operated by
their own individual keys, known as servant keys, are also
operated by an overriding key known as a master key. Such a
set of locks constitute a master keyed suite.
More complex arrangements may be required whereby sub
master keys are introduced to operate groups of different locks
the whole to be operated by a master key or grand master key
as such keys are sometimes known.
Master keyed suites have to be especially made and depending
on the complexity of the proposed keying arrangement
consultation with Imperial is recommended before ordering.
C H O O S I N G
O F
L O C K S
A lock or latch correctly fitted, maintained and considerately
used will provide many years of satisfactory service.
As a general guide, three possible categories of use may be
considered.
Light duty — for use typically in housing and other buildings
where there is a low frequency of use primarily by those with a
high incentive to exercise care.
Medium duty — for use typically in office and other buildings
where there is a medium frequency of use primarily by those
with some incentive to exercise care.
Heavy duty — for use typically in public and other buildings
where there is a high frequency of use primarily by those with
little incentive to exercise care.
It should be remembered that a lock is only as strong as the
door and frame to which it is fitted.
Tel: +44 (0) 1902 635964 • Fax: +44 (0) 1902 630675
For full range please refer to catalogue