I still have this, dad had a cart with an old 3 speed tranny on it, put the H on it with a pto shaft from the cemnt mixer, and their was another pto shaft that would go to the pipe on the back of the wagon I think low was used mostly, would pull the false front at about the right speed. Dad and 3 other neighbors would do the silage run, uncle had the chopper pulled by his Oliver, dad owned the blower, other 2 neighbors each had something.
Had a crank you stuck in the front pipe, would crank it and pull the false front back to the front.
You are making me think, they quit filling our silo after I turned 6, so it takes something to come up with the memories.
My uncle rigged up an electric motor to the tranny cart, used it a couple years that way at his place.