Enigma Uhr box
Enigma Uhr box
Production date
Additional Title information
A box for an Enigma Uhr, an accessory for the Enigma I machine.
Wood, aluminium, leather.
Cipher machine accessory
150 x 195 x 125 mm
Serial number(s)
Konski und Kruger AG
Fair. Some damage and wartime repairs.
Category / Subcategory (if applicable)
Main collection (Warwickshire, UK).
In storage
Purchased from a German dealer.
Acquisition Date
Mar 2020
Associated object(S)
Record Last Updated
Sep 24, 2023
A box for an Enigma Uhr, sometimes referred to as the 'Stecker Uhr', or 'Plug Clock’, a device introduced by the German Airforce (Luftwaffe) in July 1944 to increase the cipher security of the Enigma machine. Manufactured by the Berlin firm Konski und Kruger, the Enigma Uhr replaced the patch cables on the Enigma machine's plugboard (Steckerbrett). Unlike the box housing the Enigma machine itself, the wood used for the construction of the box for the Enigma Uhr is of a much poorer quality - reflective of the state of German manufacturing late into the War. There is some damage to the box and the metal hinges have been replaced with strips of leather, likely evidence of a field repair. As explained by the label on the box "Bei drohender Feindgefahr Verdrahtung der Rasterscheibe zerstören!", meaning "When there is an imminent danger from the enemy, destroy the wiring of the grid disk!", the Enigma Uhr was also easily disabled before being overrun with the enemy. The quality of the Uhr's spring-loaded contacts and the way the cables were soldered onto the Uhr made it easy for the device to be destroyed quickly. Likely all that was needed was for the operator to pull the cables with one hand.
The cables of the Enigma Uhr are plugged into the Steckerbrett of the Enigma machine and the wiring of these cables is altered by the scrambling disk of the Enigma Uhr. When the scrambling disk is turned, the wiring of the plugboard changes. At position 00 (no scrambling), the Enigma was compatible with machines not equipped with the Uhr. 39 different settings of the scrambling disk are possible. Whilst the Uhr seemed on paper to be a threat to Allied codebreakers, it was in fact broken very quickly.
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