Cast Iron Panel Clamp

by Bob
(Arlington, VA)

I have come into possession of three old cast iron panel clamps. They are about 4-5 feet long and have a turning tightening mechanism like a modern pipe clamp. There are two faces, one attached and the other that you can adjust using a bar with holes in it.

The interesting part is that the handle on each one says "Patn'd MAR 10 25." I'm assuming that means they were patented in 1925. I haven't been able to find any other marks to help identify them.

Anybody have any idea what these are and whether or not they might be valuable?

Thanks in advance for any help.

Bob Williams