These tools are somewhat forgotten to history at this point. Lets start with this video to explain how they work.
Being they are from 1941 they would place in the the throws of WWII , being that Snap-On was big in providing quality tools for the war effort. There would have been many applications for an abrasive disk cutter like this. Being that there was no rigid metal nameplate on this unit, tells me it was build quick and cheap for the war, no extra room for flourishes.
My unit looks to have been modified over the years, the main crank handle was replaced with shorter welded handle to allow it to operate on a flat bench without the original longer handle hanging off the side of the bench.
When I got it, it was rusted and not working. I took some time to blast it down to raw metal, and refinish all the parts. It now works and looks the part!
Here is a focus on the before and after of all the parts!