Yup, based on the photos above it does look like that's actually the wrong patent for an earlier Diebold design that built a time-lock directly into the inner lock mechanism. I assumed that must have been the right one, and you know what they say about assumptions. Apologies for jumping the gun with inaccurate info... Anyway, as 00247's post showed, this one seems to simply function as an escutcheon installed over an otherwise normal lock that would start a 15 or 20-minute countdown before opening -- basically a holdup-delay device rather than a conventional time-lock, similar in concept to the time delays built into some modern electronic combination locks designed for retail stores, etc. After a further search, I couldn't find a patent that matches this device, and it's possible that Diebold didn't complete the process to obtain one (it states 'patents pending,' but that doesn't necessarily mean a patent was granted)...I did, however, find some additional photos that show the inner workings -- apparently, the lower portion, below the twist-off cover, contains its own clockwork mechanism that controls a pin blocking removal of the cover until the timer winds down: one of the two small 'knobs' visible below the cover would wind the timer mechanism when it's in the 'locked' position, and the other would release it after the prescribed delay. It also appears that different versions of this 'escutcheon' device had either a 15-minute or 20-minute pre-set delay after winding, which would be stamped on the small window on the outer cover that appears to be blank in the OP's version.






