The large drum on this tractor was used for traction to by pass Caterpillar patents. The wide drum on this tractor also prevented the soil from compacting.The entire engine in this tractor slid forward or backward to speed up or reverse the tractor’s direction.
The Gray Tractor Company of Minneapolis, Minnesota was one of dozens of companies trying to make it big in the tractor business in the teens and 1920s. What set the Gray apart from its competitors was the large drum which took the place of rear wheels. 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.”2
One Gray owner agreed with at least some of these claims. Roy Mitchell and two partners bought an 18-36 HP Gray tractor in Winnipeg during the summer of 1918 and drove it out to the farm two miles south of Headingly, Manitoba. Mitchell said he hauled four-wheel tractors out with his Gray “when they got down so bad in the mud in the gumbo soil in the Red River Valley.”3 He went on to say that the Gray was good for travelling through snow. Mitchell took his Gray tractor with him when he moved to Star City, Saskatchewan in 1927.
There were two practical problems with the Gray drum drive tractor. One was that, given the wide bearing surface of the drum and consequent low soil pressure, the tractor bumped over every stone it encountered, and in many applications, it would hit just about every stone in the field.