TRACTOR TRIVIA and other interesting stuff 3/1/2024

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Gray Drum Drive Tractor

 

As tractors began to evolve there were no rules and no set conventional tractor to go by. By today’s standards there were some strange looking tractors finding their way onto the farm. The gigantic prairie tractors were not well suited for smaller farms. Numerous three wheeled configurations were developed with steering in the front and others with steering in the rear. One drive wheel or two drive wheels, lots of offerings were made by a variety of manufacturers. Drum Drive tractors were one of the strangest appearing contraptions, but from an engineering standpoint the design was brilliant.

 The drum was 54-inches wide and could be equipped with cone or spade lugs. The two front wheels with automotive-type steering were each 8-inches wide and 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 bury 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 from the previous pass.

Tractors in the early part of the twentieth century were heavy and the use of the drum distributed the weight over a substantially greater area reducing soil compaction. Gearing for differentials and ring and pinion drives was expensive and worm drive systems didn’t hold up well for massive machines. A simple chain drive is all that was needed on the drum drive tractor. I expect that others also manufactured Drum Drive Tractors but Gray’s was a financial success.

W. Chandler Knapp is credited with having developed the concept and design of the Drum Drive in 1908, however he had no plans to manufacture it. The Knapp Farm Locomotive began as a shop-built four-wheel tractor with rear drive wheels and evolved into the drum drive to reduce root damage in his orchard and to better cope with muddy areas.

Gray Tractor Manufacturing Co. of Minneapolis bought Knapp’s company and design in 1914, there is little information about the sale so this is a gray area (pun intended). The “drum-drive” tractor was renamed the Gray Model A 20-35.

A smaller Model B 15-25 was later added to the lineup. In 1917 the 18-36 model was introduced; this model was built until 1922 and was the company’s most popular tractor. It was powered by a 4-cylinder Waukesha engine. The enclosed power train consisted of spur gears and a roller chain final drive.

Gray built a model especially for the Canadian market as the drum-drive worked well in snowy conditions. It was known as the 22-40 HP Canadian Special.

According to company advertising the drum offered ten advantages: “Simplicity of construction; does away with all bevel gears and differential; distributes weight over a larger surface; avoids packing of the soil and injury to seed bed; ideal for soft and wet land; gives double traction surface; supplies more power to the drawbar; produces a never-slip grip; affords easy steering and turning, and rolls everything flat before plows.”

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 operator platform design left a lot to be desired, the operator sat at the rear of the tractor with his view obscured by the engine cover. The seat could be rotated to the right side but the operator would then need to look over his shoulder to see where the tractor was going.  

Company advertising indicates the tractor stayed into production until 1933.