Allis Chalmers Self propelled combine?

Stan Wolf's Allis-Chalmers SP-40 self-propelled combine was born in 1940 of a perceived wartime necessity to decrease the country's reliance on foreign markets for strategic grains. In this particular case, the War Department was interested in developing varieties of Rape (Brassica napus), an annual plant in the cabbage family, for its seed oil, which is a key ingredient in synthetic rubber.

As part of that effort, the Army Corps of Engineers was handed the task of developing a self-propelled test-plot combine, and they chose to work with Allis-Chalmers on the project. Essentially, the Model SP-40 consists of a Model 40 pull-type combine mounted on a small truck chassis. The wheels and tires are standard military issue, complete with brake drums (but no brake shoes). An Allis-Chalmers Model G rear-engine tractor is mounted above the combine and powers the drive wheels and hydraulic system. A separate, air-cooled Wisconsin engine was mounted low and on the side of the unit to power the harvesting and threshing components. The operator's station was high above the cutter, which offered excellent crop visibility, but with its narrow 40-inch width, the machine can be easily upset.

Stan's Model SP-40 is one of five built, and one of three known to survive. This particular unit was assembled at the Letterkenny Army Base near Chambersburg, Pa. 'I obtained it about 20 years ago after it had been stored at the base for over 40 years,' Stan says. 'It was painted army khaki, but I chose Allis orange when I restored it.' One of the other two SP-40s is in a museum in Oxford, U.K. The other is in the hands of a private collector