OK, I'll give it a try.....
My guess is an old thresher or combine. My dad's uncle had one of those (not exactly like that though) that was pulled behind a tractor. Rather than dumping seed or grain into a bin, it was blown directly into sacks so it took two people to operate; one to drive the tractor, and another to ride the combine and change sacks on the blower.
Did I win a prize ?? /forums/images/graemlins/smile.gif