1928 John Deere D
Despite a rather severe farm economy depression at the time, Deere management decided to build a Model D prototype in 1923, designed by Muir L. The Deere Model D was produced from March 1, 1923 to July 3, 1953, the longest production span of all the two-cylinder John Deere tractors. Over 160,000 were made. The first Model D rode on steel wheels with a 6.5 in × 7 in (170 mm × 180 mm) (later 6.75 in × 7 in (171 mm × 178 mm)) two-cylinder hand-cranked engine rated 15–27 hp (11–20 kW).
By 1925, the company realized the standard Model D did not meet customers' needs for industrial applications. Steel wheels were not suitable for hard surfaces, and the gearing was too slow for safe road speeds. Solid rubber tires were added, and engineers fitted a 28 tooth sprocket to the final drive, giving a road speed of 4 mph (6.4 km/h). The company replaced the 465 cu in(7.62 l) 2-cylinder engine with a 501 cu in (8.21 l). In 1926, Deere advertised the model the "John Deere Industrial Tractor" with 40 × b inch rear wheels and 24 in × 3.5 in (610 mm × 89 mm) fronts with solid tires. This would become known as the DI. Options also included wheel weights.
By 1925, the company realized the standard Model D did not meet customers' needs for industrial applications. Steel wheels were not suitable for hard surfaces, and the gearing was too slow for safe road speeds. Solid rubber tires were added, and engineers fitted a 28 tooth sprocket to the final drive, giving a road speed of 4 mph (6.4 km/h). The company replaced the 465 cu in(7.62 l) 2-cylinder engine with a 501 cu in (8.21 l). In 1926, Deere advertised the model the "John Deere Industrial Tractor" with 40 × b inch rear wheels and 24 in × 3.5 in (610 mm × 89 mm) fronts with solid tires. This would become known as the DI. Options also included wheel weights.
