Spent meny hours on the binder both driving the tractor (VAC case) and riding the binder. Dad liked square corners and if you timmed it correctly you could easily make square corners. The bull wheel stayed engaged while turning and I would assume that it would roll backward a bit. Don't Remember. Never thought about how that worked with horses. We used the horses on the bundle wagons, but not the binder.
One job for the binder rider in additon to keeping an eye on everything was to drop the bundles in a straight row. Dad used to say that if you did it right you could shoot a .22 down the end shock and hit all the shocks. Doubt that ever happened.
Brings back good memories. remember one year when the oats was taller them the rear wheels on the VAC. That combined with the occasional clumps of Canadian Thistle made for interesting bundles. Hated shocking the bundles with thistle. Seems like it was always hotter then hell and we had to wear long sleeve shirts.
Just hauled Dad's Minnesota Binder home and plan to restore it