A permutation lock chamber has a chamber shaft extending therethrough which is held against rotation when the chamber is in a locked condition and which is rotatable when the chamber is in an unlocked condition. The chamber shaft is connected to the shaft of an outer door handle through a clutch. When...http://www.google.com.au/patents/US5040652?utm_source=gb-gplus-sharePatent US5040652 - Cylindrical and permutation lock arrangements with clutch
