History of Locks
The Code Lock - An Interesting Lock
By Brian Morland
» THE CONCEPT OF A CHANGE-KEY lock is well known and traditionally applied to safe and strong-room door applications . The convenience of quickly changing the combination of a lock when keys were lost or stolen is obvious ; it ’ s even more important for governments during times of intense diplomacy and conflict to re-calibrate or re-combination locks . One lock that fulfilled these criteria , and used by the UK Ministry of Defence dispatches during WWII , was the Code .
Although a patent was applied for as far back as 1938 by B Sterner the full patent was issued in July 1947 after the war . Perhaps whilst it was on the secret / restricted list its principles were kept from general knowledge .
When it was in use by the Ministry , it was marketed by The Code Lock Ltd who were based in Middlesex . After the war the lock was de-classified and was initially marketed more generally , at some point Marketing was taken over by J Brockhouse & Co Ltd . So far it ’ s not been learnt if Brockhouse now owned the company .
Two factors caused its demise notwithstanding its intriguing design ; one was that due to the components being die-cast from zinc alloy it didn ’ t stand up very well to continuous use , and the other reason a ‘ theoretical ’
CODE padlock , used extensively on dispatches during WWII by Ministry of defence .
weakness was identified in that it could be picked – but it ’ s not likely it was ever compromised in the field . Like many things ‘ ministry ’ a weakness identified results in a change in design or abandonment . Improvements in die-casting , high pressure die-casting , came too late and the lock dwindled into obscurity ; the complexity of the internal part shapes meant that they had to be produced this way on viability economic grounds . The perceived picking weakness though could have been addressed .
The cylinder was , as previously stated , made entirely from die-cast components . At first glance the key looked as though it might operate some
The two versions of the CODE key ; above : Fixed CODE key and below : Adjustable CODE key
kind of RPT or Bramah style lock . In fact the six various length steps on the key engaged with radial shaped two part wedge shaped tumblers . The lock itself , from new , was supplied with a neutral combination . The lock was also supplied with two fixed code keys and a special adjustable key ; this was used to set the initial combination and also to reset the combination to a new code as and when required . A special kit of key combination parts could also be ordered to assemble fixed keys to the code set by the adjustable key .
Instructions to set and reset the Code Lock taken from the manufacturers own paperwork supplied with the lock are reproduced here since to my knowledge these notes are not generally available elsewhere : -
Rim Deadlatch , this example still mounted on its original promotional stand .
Another design , illustrated in the contemporary sales broacher .
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MAR / APR 2021
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