What is it? CXCV

I've found another patent: 1,479,796. It's John Endebrock of the Trailmobile Company describing the automatic coupler. He filed the patent in 1919. His drawings may not be to scale. A 1-1/4" kingpin sounds big enough for the weights they pulled in those days.

The lock doesn't look thick enough to cover the whole shaft of the kingpin. It would serve its purpose as long as the clamp couldn't get between the lock and the trailer's fifth wheel.

It looks as if the shoulder would partially block the keyhole if it stuck out more than 1/8" or so. So you slide the lock up the shaft, away from the shoulder, to the bottom of the trailer's fifth wheel. Well, don't slide it up so far that the loop on the key hits the shoulder. Sliding the lock up should make it easier to use the key.

I wonder if a tumbler lock would have been more subject to jamming from corrosion or dirt. The downward-facing keyhole might make it tough for a lockpicker. He'd need to be on his back at the right height, and he'd have to worry about grit in his eyes.

Thanks for finding that, I added it to the answer page as a possible application for the lock.

Rob

I've made "prototypes" before for this-and-that... if I had failed to leave enough room/clearance to insert the key in a reasonable manner, it would have been corrected before any production took place. I can think of ways to make it work too, but it wouldn't make sense if it was for this exact purpose.

It should be quite protected underneath the trailer and I doubt that debris would be a problem. Plus the patent you already referenced has the key going in the side and appears to use a tumbler lock. They seemed to be okay with it. I would guess that where the lock was stored when it wasn't being used would be the most troublesome :)

Right now I don't have any better ideas...

Well, of course I don't /know/ it was for a trailer kingpin, but I'd like to argue for the possibility.

I'm thinking of a lock devised about 1919, when Trailmobile began making automatic couplers. The lock may not have been patented. It may have been an adaptation of a handcuff design.

The patent I found was filed in 1951. Trailers were much bigger, with locked doors to protect cargo. Roads were paved and couplers were standardized. A driver with a skeleton key could move a trailer hundreds of miles before it was reported missing. That would be a reason to use a tumbler lock.

It seems to me that it would be hard to design a collar lock keyed from the side that would be resistant to opening with a chisel. Still, with so many trailers full of valuable cargo, it could be worth an inventor's while to devise something more convenient than other locks.

I imagine RH's lock may have been made when there wasn't a big market because there weren't many automatic couplers and truckers weren't so concerned with locks because cargoes weren't so valuable and trailers couldn't be taken very far very fast.

I think such a lock would be keyed from the bottom as a simple way to keep it resistant to a chisel. The inventor might use the smallest possible key clearance because a smaller collar could be harder to chisel open.

I say this because I don't have any better ideas, either.

Yes, it is a lever lock, having three spring loaded levers with hooked ends which all must be raised to release the "tongue", or whatever that heavy projecting piece is called.

There are no discernable lettering or other markings on it.

I bought it at an antique shop in Cambridge, Massachusetts aver 30 years ago, and every once in a while I ask around hoping to get a cite on a definitive answer about it's application.

I tend to think it was either a prototype, or maybe a "master piece" made by an apprentice locksmith as a requirement for proving his skills for making the transition to become a master locksmith.

Jeff

Hi Jeff,

Can you lock it with out the key? It appears like it would simply snap shut without use of the key.

The reason I ask is that would limit its uses. If someone were to use it where only one side is accessible and could lock it without the key... oops! Now how do you unlock it? The key hole could be blocked. I'm thinking about the kingpin idea for one. It would be difficult to unlock it with the keyhole on top, if not impossible. Maybe that is why we don't see more of them around :)

This item is pretty well stuck in my memory. If I ever figure it out or come up with a really solid lead you'll hear about it.

Yep, just squeeze it closed and the hooked ends of the three spring loaded levers slide up the "ramp" and drop down behind it.

Thanks, my curious mind would sure like to know if it's a "one off" piece or something with a definite useful application.

Jeff