Written By Larry Gay
As tractor design began changing from the giant prairie-type tractors to smaller sized tractors in the 1910s, three-wheeled tractors became popular. However, there was no standard configuration. One configuration had one drive wheel on the rear, a steerable wheel in front, and an idler wheel in the rear. Other tractors had two drive wheels in the rear and one steerable wheel in front. Another configuration was two steerable wheels in front and one drive wheel in the rear The Gray Wide Drum tractor was unique with two steerable wheels in front, but the rear drive wheel was a wide drum.
The Gray tractor started as a three-wheel tractor with a rear drive wheel built by W. Chandler Knapp in 1908 to operate in his orchard in New York. Each year it was improved with a wider rear drive wheel, but mud collected in the spokes. The final improvements replaced the wide rear drive wheel with a wide drum with tight ends and no spokes and turning the engine crosswise so spur gears could be used instead of bevel gears to transmit the power. Manufacturing was established in Minneapolis with the Gray Tractor Company and the tractor was introduced at the Power Farming Demonstration near Fremont, Nebraska, in August 1914.
The final version of the Gray Tractor with the Wide Drive Drum was rated at 18 drawbar horsepower and 36 belt horsepower. It was powered by a 4-cylinder Waukesha engine. The enclosed power train consisted of spur gears and a roller chain final drive. The company advertised the tractor did not use bevel gears or a differential. There were two speeds of 2.25 and 2.75 mph, but the final drive sprocket could be changed for a top speed of 3.25 mph. A corrugated sheet metal hood covered the engine and the wide drum. The tractor operator was seated at the rear of the tractor, near the right side.
The drum was 54-inches wide and could be equipped with cone or spade lugs. The two front wheels with automotive-type steering were 8-inches wide and were positioned wider than the rear drum, so the tractor rolled a 70-inch wide strip. The primary feature of this configuration was the tractor did not compact the soil and the standing corn stalks or vegetation were flattened when the tractor was plowing, enabling the plow to completely cover the crop. The tractor’s heavy frame allowed implements to be attached to the side of the tractor for a one-pass operation. For example, a small disk could be positioned on the left side of the tractor to cut the vegetation, a 4-bottom plow behind the tractor to turn the soil, and a harrow on the right side to smooth the turned soil.
Larry Gay is the author of four tractor books published by the American Society of Agricultural and Biological Engineers, including Farm Tractors 1975-1995 and Farm Tractors 1995-2005. The four books may be obtained from ASABE by calling 800-695-2723.