The Unique Allis-Chalmers G Tractor
May 13, 2014
Written By Larry Gay
During the late 1930s, the tractor companies began to realize small farms needed a tractor smaller than the 2-plow, 2-row cultivating tractor. As a result, the Allis-Chalmers B, the John Deere L, and the Farmall A tractors were introduced. These were rated as 1-plow tractors which straddled one row when cultivating corn or cotton and were the size needed to replace the horses and mules on small farms. Each of these tractors utilized a minimum amount of frame between the engine and transmission to provide good visibility for the operator when cultivating. In 1947, International Harvester introduced the Farmall Cub, a smaller version of the Farmall A, and Allis-Chalmers introduced its Model G tractor in 1948.
The Allis-Chalmers G tractor was unique as the engine was located at the rear of the tractor, behind the rear axle. The fuel tank was placed over the rear axle and the transmission and operator’s seat were located just ahead of the rear axle. The only structure between the operator and the front wheels was an arched frame consisting of two thin tubular members. The matching plow, planter, or cultivator was carried under the arched frame, ahead of the operator, for excellent visibility. A variety of planters and cultivators were available for planting and cultivating a single row of corn or cotton, two rows of large vegetables, or four rows of small vegetables.
The power plant for the Model G was a Continental 4-cylinder gasoline engine with a 2.38-inch bore and a 3.50-inch stroke which resulted in a 62-cubic-inch displacement. This provided 10.3 belt horsepower and about nine drawbar horsepower which enabled the Model G to "push" a 1-bottom, 12-inch moldboard plow. The unique configuration of the Model G with the weight of the engine, transmission, and operator over the rear axle provided excellent traction. The 4-speed transmission provided a special low speed of 1.6 mph at the rated engine speed of 1,800 rpm and even slower at partial throttle for close cultivation of small crops. The other three speeds were 2.2, 3.5, and 7.0 mph.
Both the front and rear wheel treads were adjustable in 4-inch increments from 36 to 64 inches. The 6.00-30 rear tires were narrow enough to fit between the rows of closely spaced crops. Although the Model G was a small, low-cost tractor, standard equipment included a starter, electric lights, a muffler, and a swinging drawbar. The belt pulley and a hydraulic lift for the implements were optional.
The Allis-Chalmers G tractor was produced from 1948 through 1955 and is still being used by some growers of specialty crops. Also its unique design makes it is very popular with tractor collectors.
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.