Looks custom made. Can you tell us what happens when you turn the screw handle? Does it push or pull the upper jaw? Can you disassemble it and show the pieces? I'm with Kevin on the adjustable pin spanner except it looks like the screw pushes the jaws apart, not pull them together.
lg
no neat sig line
It does not come apart. When you turn the handle clockwise it opens wider, when you turn it counterclockwise it closes until the pins touch.
I suspect because of the hex on the body (near the threads) it is intended go close tightly around a specific object, and you would use a separate open end or adjustable wrench to hold it while you twist the handle to tighten the jaws with the pins.
What makes me scratch my head is what do you do when its tight? The treaded rod is not strong enough to take much torque, so it would not make much of a wrench.
Its obviously well used, so its not a one job and stick in the toolbox special tool.
Appreciate all the ideas.
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