This is a wagon wrench, we find lots of them in France but there are several early American makers also which crop up over here.
Used for general agricultural work and handle the larger old style square nuts quite well.
Ususally heavily abused but nice condition ones with a good makers name can do quite well especially USA ones
I normally have to replace the wooden handle because of worm or damage, only do it on the really nice ones.
Cheers, Martin