The Missing Link in Tractor Development

Tracking the elusive auto tractor.


A 1913 patent drawing of the auto tractor. Inventor Walter Zimmerman filed an earlier patent in 1911. Patents for both designs were granted in 1917, but whether auto tractors were still being produced then remains a mystery.

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"The auto tractor consists of a steel frame upon which the automobile is carried and to which it is firmly held when in operation. The frame is carried on two traction wheels 6 feet in diameter. Connecting the two big wheels is a steel axle upon which is mounted the gearing, which transmits the power from automobile to tractor wheels.

"The belt attachment for power work is mounted on the rear end and put in operation by means of gears controlled by feather keys. A radiator, water supply tank, centrifugal circulating pump and connections are supplied to ensure the cool running of the automobile engine under all conditions.

"In order to attach the automobile to the tractor, the car is backed up with the rear wheels straddling the tractor frame until the saddles strike the inclined top of the frame. The automobile is then pulled back into place with its own power by means of ropes fastened to the hub gears which act as winding drums."

-The Pacific Homestead, Salem, Ore., 1911.

A search for a missing link in tractor evolution is not quite the same as the archaeologist's search for the missing link between the monkey and man. But the search for the missing link between the early single-cylinder tractor and the modern high horsepower tractor retains considerable interest for me.

That quest caught fire when I discovered the Auto Tractor. As a lifelong journalist who's specialized in farming and farmer-invented technology, I was amazed by the contraption, a mind-boggling, Rube Goldberg-type machine. I'd never seen anything quite like it, nor had I ever heard of it. Yet as cumbersome and ungainly as the unit appeared, it could be something special. I was struck by the possibility this was one of the first - if not the first - embodiments of the modern farm tractor.

The Auto Tractor, as described in company literature, "is an attachment for any automobile and is so designed that when attached to the automobile, the road speed of the latter is decreased and the pulling power increased about 14 times. This ingenious machine attaches to any standard automobile, making it possible to plow, disc, harrow, sow, harvest and thresh and do other work, using the automobile engine and transmission to furnish the power, and the Auto Tractor to convert this power, so that it is available for use on the farm."

Literature on the Auto Tractor placed it as entering the farm scene in about 1911. Up to that time, farm tractors were huge, ponderous affairs, usually powered by an engine with a single large cylinder. Hart-Parrs and OilPulls come to mind. At the same time, C.L. Best of California had made the move that would make him the father of the Caterpillar, but the result was a much heavier tractor than most farmers would want.

Other combinations of an automobile and a set of tracks existed, but again, none of these appeared to be the forerunner of the popular-sized tractor ultimately accepted by the American farmer.

The Auto Tractor, on the other hand, did have ponderous drive wheels, but the engine, drive wheels and gearing had a great deal in common with today's tractor. Here was the multi-cylinder automobile engine providing up to 40 hp. Also, the Auto Tractor had the necessary gearing to convert that horsepower to turning traction wheels with enough ground grip to pull 6-bottom plows. The gears were admittedly huge and non-lubricated, but they existed as a functioning component nonetheless.

The Auto Tractor's primary inventor and producer was Walter Zimmerman, Earlville, Ill. Zimmerman, a true believer in his machine, set up a manufacturing plant and production line in Niles, Mich. According to information found at the University of Illinois archives, the enterprise was organized in 1911. By 1915, more than 1,000 Auto Tractors had been built. Many apparently went to Oregon orchards. Archives photos showed the units at work pulling plows, discs, log wagons and road graders, even providing belt power for a threshing machine.

The most complete description of the Auto Tractor's use was in a June 8, 1914, article in the Pacific Homestead, Salem, Ore. The author reports operation of an Auto Tractor on a 25.6 hp 1911 Buick (averaging 2 mph) at the Veritas Orchards, Medford, Ore. Some things never change: "The farmer today is called upon to increase production per acre to feed the people of the earth," the author notes, "and his only means of doing this is to increase the efficiency of his producing methods."

The concept of converting an expensive, open touring car into a dual-purpose vehicle seems doomed from the start. Inclement weather, rain for instance, would take a toll on the car's interior. And anyone who's ever farmed in mud understands immediately that there could be no practical way to disconnect the tractor and then use the car for pleasure.

I have been unsuccessful in my efforts to locate a surviving Auto Tractor. This "missing link" in tractor development has apparently eluded the collector. Perhaps the unit was a victim of its time. The company existed in the early 1900s. Could it be that every Auto Tractor unit produced (more than 1,000) was melted down for World War I armaments?

- C.F. Marley is a retired freelance writer and editor. Contact him at P.O. Box 93, Nokomis, IL 62075.