Sorry, I hadn't noticed the 2nd sheet.
It can be used for a lot of purposes for checking force or weight. Technically, you could use it as a torque wrench, but not very accurately with that guage.
If you know the area of the piston face, multiply that by the guage reading to get the force applied to the bottom side of the tool.
If the piston face us 1/2 sq, in. and the guage reads 100 psi you are applying 50 pounds per square inch of force.
I guess sonetines you may want to apply an exact force to a part. Maybe it can be used on a press between the ram and a part? Another use could be to make sure weight is distributed equally between various points.
Be careful though, a 1/2" piston face is close to 1/4 sq. in. I always think of it this way, in a 1" square there are four 1/2" squares. Circles are a little different - radius squared times pi.
I hope I'm accurate, my brains fried. Big tool day for me and it wore me out. It seems like a pretty specialized tool, but it also seems more accurate than a spring mechanism.
I wonder how it would perform compared to electronic force measuring tools.
Chilly