> part of a power hacksaw...
My WAG is it's a jig for sharpening lawnmower blades....
The second brass thing is the top of some cartridge filter, but there is no way I can guess what for...
The blue thing is an air line water seperator for compressed air. (it's not usable in that state btw;)
The last thing I dunno, part of a propane stove?
Cleaning out the garage is always a sure way to loose some hair headscratching - P