A mechanism comprising a code wheel assembly including a first element, a second element and a third element, a element, a plurality of main code posts preset for locking the first element and the second element in driving relation, selectively operable means for actuating the main code posts sequentially...http://www.google.co.uk/patents/US4333073?utm_source=gb-gplus-sharePatent US4333073 - Electromechanical decoder
