Key lock adjustable

[Papaw]

From an email-

Hi,
I have an adjustable wedge or key type wrench that is 41" long and can't seem to find any info on this type. Was wondering if someone may have an idea of what it is or was used for. I was told it was from the railroad but don't know. It does have tool marks that look like it was cut out with some sort of gas torch.

I think this is a shop made wrench, anyone else have any thoughts?

[leg17]

Could possibly be some sort of adjustable gage.
Why would the RR fabricate a wrench like that instead of buying one?

[Wrenchmensch]

I have a similar, but smaller, key wrench, e.g. it also uses a tapered key to hold an adjustment position.  Mine is an earlier hand-forged tool made of iron.  The design principle of using a key to lock adjusted jaw openings was originated as early as the late 18th century, and remained in use into the twentieth century. In 1903, Loring Coes, obtained a patent covering his well-known Coes Key Model. This model, which used a screw to adjust its jaws and a key to lock the adjusted jaws, came originally in 28, 36, and 48 inch lengths .

[johnsironsanctuary]

I'm thinking that the key as shown is in from the wrong side.

[Papaw]

I'm thinking that the key as shown is in from the wrong side.

I agree.

[rusty]

No, the key is in the right way, the bump is to keep it from falling out, the thicker end is opposite the head (and the bump), where it should be, so the force between the jaws cams into the wedge...

It seems rather well made to be a hand made one off, but it could be....

If it is a railtroad tool, it is a very early one, as the railroads tended use relatively modern designs....(It's not implausable)

[Branson]

I'm with Rusty.   Same principle as used for the guides on pre-1850 plow planes and early panel gauges.