Yeah, that's a big set of pliers alright. Nice! From what I can glean on the web, Eagle Claw pliers were well thought of and fairly popular. Yet today there really isn't a similar-type tool at any of the hardware stores in my area. So I wonder what application they were used on back in the day, that is no longer needed today?
Carriage bolts as in the ones with domed heads? Or carriage bolts as in the ones used 100 years ago on carriages? (or maybe they are the same thing) (Image removed from quote.)
My best guess is as good as yours. I believe the photo you have describes a carriage bolt. I need to do a little more investigating to see how these pliers would work better with Carriage bolts.