HISTORYOFLOCKS
SPONSORED BY ADVANCED KEYS
George Price developed
and combined his own antipressure feature in his Ne Plus
Ultra patents. This lock which
also incorporated a hardened
nozzle and gunpowder proof
features was respected by
many and Price himself
believed that it couldn’t be
improved.
It is interesting that not all the
main safe companies used the
moveable bolt stump antipressure device: Tann preferred
their guarded lever, and Ratner
, false notches - although both
also incorporated a secondary
live re-locker system which
blocked any pressure onto
the levers until all levers were
correctly and simultaneously
lifted.
Chubb does not seem to
have gone down the antipressure route either, initially
refining the detector and
later developing the Gibbons
detent which has much the
Price’s anti-pressure lock
with comb springing and
made powder proof by
placing the keyhole in the
middle of the levers.
same effect but in the end was
troublesome, causing lockouts.
As late as the 1950s, however,
Chubb was making diplomatic
bag padlocks with an antipressure mechanism at the
insistence of the Ministry of
Works (MWP).
An extension on each lever held down a spring loaded pin in the
Tann ‘Reliance’ anti-pressure device which only released the
bolt when all levers were correctly and simultaneously set.
‘Today, the antipressure is still
used in high security
applications’
Today, the anti-pressure
is still used in high security
applications and can be seen
in the UK Government Mersey
lock.
So perhaps the perfect
combination for security
could be the double acting
lever combined with an antipressure device. When used
together and well made the
lock offers extremely high
resistance to surreptitious
entry methods.
A prototype padlock, modified
by Bill Stanton of Chubbs R&D
department, to incorporate an
anti-pressure device at the
insistence of Ministry of Works.
Brian Morland, curator of
the Heritage Collection of
locks and keys, welcomes
comments and corrections
on historical aspects of
locks and keys. Brian can be
contacted by e-mail: brian@
morlands.demon.co.uk
34
MAR/APR 2014
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