Tractor Trendsetters: John Deere GP
Jun 12, 2012
Written by Larry Gay
In the early 1900s, farmers and the farm equipment companies were searching for a way to cultivate row crops with power equipment. Motor cultivators were built from about 1915 to the early 1920s, but not many farms could justify owning both a tractor and a motor cultivator. A better solution appeared in 1924 when International Harvester started producing the McCormick-Deering Farmall tractor. Now there was a 2-plow size of tractor on the market that could perform the usual drawbar, belt pulley, and PTO tasks plus cultivate row crops.
The Farmall used a high clearance rear axle and a 74-inch wheel tread to straddle two rows of crops. The dual front wheels ran between the two rows. In 1927, John Deere introduced a different configuration of row-crop tractor with its Model C tractor, which became the Model GP during 1928. The John Deere GP tractor was built to cultivate three rows with an arched front axle straddling one row. The 49.5-inch wheel tread enabled the front and rear wheels to run in the spaces beside the center row. A 3-row, tractor-mounted planter completed the system. One advantage of the relatively narrow wheel tread was it eliminated side draft while pulling a 2-bottom plow.
The John Deere C and GP tractors introduced a mechanical power lift to raise and lower the planter or cultivator. The operator stepped on a pedal to raise the implement at the end of the field and then stepped on the pedal again to lower the implement after making the turn for the next trip across the field. The power lift was also used to raise and lower the front-mounted sweep rake. Now there was a fourth method of using tractor power to replace manual labor.
The John Deere GP tractor was rated at 10 drawbar horsepower and 20 belt horsepower with its horizontal 2-cylinder engine which operated on kerosene. The transmission provided three forward speeds of 2.3, 3.1, and 4.3 miles per hour. The PTO and power lift were a combined system.
The 3-row concept did not become popular and the GP was joined by the GP Wide-Tread in late 1928 and early 1929. The GP Wide-Tread was designed to cultivate two or four rows as it had dual front wheels and a 76-inch rear wheel tread. However, the mechanical power lift did become a popular feature and was soon provided by the other tractor manufacturers.
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. These books may be obtained from ASABE at 800-695-2723 or asabe.org, click publications and then click book catalog.