I'm going to try to find some time one of the next few days to set up a proper light-tent and get some proper photos... but, for now, here are a few quick snaps from my iPhone.
Yale & Towne started producing this model in 1892; from what I can determine, this particular unit dates from around 1900. Time locks were being quickly adopted in the late 1800's and early 1900's... combination locks on vaults were becoming so good that some thieves were resorting to simply kidnapping the bank managers, driving them to the bank and forcing them to unlock the vault. Time locks quickly eliminated that trend.
This time lock would normally be mounted on the inside of a vault door, and someone would set it each night to the number of hours that the bank was going to be closed and the vault should stay locked. (The movements in this model will run up to 72 hours, to allow for a 3-day closure over a long weekend; it was running when I took these photos, so some of the pictures of the clockwork may look a bit blurry.) The cover is normally locked closed: the three "buttons" on the front pivot to the side and allow a clock winding key to pass through and wind each of the three clock movements independently.
The three time movements are there for redundancy (the chances of all three of them failing overnight is pretty slim); whichever of the three time movements first reaches "0" will slide the horizontal bar across, signalling that the vault should now be open. Given this particular case design, the bar at the very bottom would have (typically) been connected to a second spring-loaded mechanism whose job was to actually throw the bolts and unlock the vaults. (As odd as it sounds, in some cases there would not have been a combination dial at all.)
This design proved very popular for Yale & Towne, as it used modular time movements: you can easily swap out any of the three movements if they break. This lock still has all three original, sequentially-numbered movements. (The serial numbers appear on the case of the movement and on the dials.)
The amount of care and detail that went into the craftsmanship in the vault locks from that time, down to the smallest screws, is truly amazing. The macro on an iPhone isn't great, but you can get a sense of the level of detail in the clockwork mechanism. (Again, it was running at the time, so things are a bit blurry.)
For a 110+ year-old piece, I'm really happy with the condition it's in: it still has the original glass, hardly a scratch anywhere, and it runs perfectly. The only thing I have left to do is make a proper key for the door; that was one piece that was lost along the way somewhere, and I've had to fashion a temporary one for now. It's frustratingly close in dimensions to a standard handcuff key, but the shaft of the key needs to be 1/8", which is just slightly smaller.
