Early on in tractor design was the auto-plow. The Auto-Plow was a tractor with the plow blades already mounted to the bottom of the tractor. Left is a 1912 Hackney Auto Plow. It is believed to be the only running one of it's kind housed at the Martha and Dale Hawk Museum in North Dakota.
Notice wheel in front of the tractor. You would turn this wheel to start the engine.