billybob_81067
Redneck
I think we had this conversation on PBB a couple years ago!
I've never found a clear catalog/diagram on how they work. Seems like they may have been hydraulic, air over hydraulic or just air.....maybe it was optional depending on size or clamping force or something. There aren't too many of them left out in the wild.
You could probably put yours back together and sell it for enough to be a new, big boy wilton. Vices are stupid collectible right now and I think people would pay big money for a rare one like these.
From that picture it looks like air over hydraulic with a master cylinder full of oil, and the cylinder on the vise acts like a slave cylinder... That would increase the pressure over just the air because the "master cylinder" would have a bigger surface area for the air to push against. Interesting!