HISTORYOFLOCKS
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‘the lock
automatically
readjusted itself
to the new key
rendering any other
key ineffective’
the combination of his lock at
will, by simply rearranging the
steps on the key.
The key was made where
the steps or lever cuts were
separate and could be
removed from the key and
reassembled in a different
order. When this new key was
used in the locking process, the
lock automatically readjusted
itself to the new key rendering
any other key ineffective. This
was a great advantage because
the new arrangement could be
effected quickly by the owner
at any time without the need
to dismantle or change the
lock or call in the lock makers’
engineer.
‘still retaining the
ability to ring the
changes to the locks
full potential’
A Hobbs key with both adjustable and detachable features.
Although these ‘adjustable’
key steps were very valuable
in enhancing the security
they proved fiddly and
time-consuming for users
to accomplish and so a
development of this idea was
sought. The answer was a
key which still retained these
adjustable steps but also
had the whole of the key bit
capable of being removed. The
idea being that a spare bit was
kept in readiness or even a
number were kept and used at
random, but still retaining the
ability to ring the changes to
the locks full potential.
In practice these steps proved
far too fiddly, most choosing
to adopt the detachable bit
feature. So the next generation
of change key locks were made
with sets of solid bits that
The Hobbs Bankers Change Key (BCK) lock variant that replaced the
Parautoptic. Note the knife edges behind the bolt head. This lock also
had the capability to prevent key crossovers to other institutions locks.
To read more, visit www.locksmithjournal.co.uk
The key bit detached from the stem. These BCK
locks were made in up to 12 lever versions.
The key bit that simply slid into the hollow key stem.
could be attached to the key
stem and used at random.
By now, safe and vault
doors were getting thicker
and the detachable bit idea
was adopted to solve another
problem. It is obviously
inconvenient to carry keys
longer than around 150mm
(6”), to say nothing of the
security implications. The key
stems whatever the length
could be kept on site under
moderate security and just
the removable key bit kept
securely. Many manufacturers
provided short carry stems or
leather wallets for safe keeping
the ‘business’ end of the key.
In the end, however, and
although detachable bits
remain popular today,
failures occurred with the
‘most institutions
at the very highest
level abandoned
detachable bits
in favour of solid
one piece keys’
mechanical union of bit and
stem, especially on high usage
or very thick doors. Most
institutions at the very highest
level abandoned detachable
bits in favour of solid one piece
keys, some being very long to
suit the door thickness. There
is nothing worse than a key
that has become detached
some 18 inches, or more,
inside a vault door, perhaps
irretrievably wedged in the
THE MAY/JUN 2014 ISSUE
SPONSORED BY ASSA ABLOY Security Solutions
35