This is something I found in a box of parts it is adjustable and has a bushing inside fixture
Finally, an easy one. That's a very small ineffective WW2 cannon.
That looks like it is out of a 1950's Craftsman wood working tool. They had those type of bearings in them. There was some thing like that on the bench top belt sander. They held the roller that adjusted the tension on the sanding belt.
Thank You Bill
Those were used in pairs to hold a jackshaft between a motor and the tool under power. The way they're made, they will be self aligning and not bind on the shaft even if assembled carelessly.
I once had a pair of those that held a step pulley that matched a step pulley on a double-arm jig saw. With this arrangement, a standard 1725 RPM motor was able to be used, and speed was reduced sufficiently to keep from shaking the saw to pieces.
actually, it was more correctly called a scroll-saw.