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Tractor Trendsetters: McCormick-Deering WD-40

Sep 15, 2010

Written By Larry Gay

It was not a surprise that every new farm tractor on display at the recent Farm Progress Show was powered by a diesel engine. In fact, it has been that way since 1978 when the Nebraska Tractor Test Lab evaluated its last tractor with a gasoline engine, the International 284 utility tractor.

Diesel engines first began to appear in U.S. crawler tractors in the early 1930s. Then 75 years ago, in 1935, International Harvester introduced the McCormick-Deering WD-40 and advertised it as “America’s first diesel-powered wheel tractor.” The WD-40 was the standard-tread W-40 tractor with the diesel engine from the McCormick-Deering TD-40 TracTracTor crawler. IH advertised it operated on diesel fuel which cost less than gasoline or kerosene and used one-third less fuel than a gasoline engine with the same horsepower. The WD-40 was rated as a 4-plow tractor with 44 belt horsepower and 28 drawbar horsepower. It could be equipped with steel wheels with a variety of lugs or rubber tires. A PTO and lights were optional. 

This early diesel engine had four cylinders with a 4.75-inch bore and a 6.50-inch stroke, resulting in a 460-cubic-inch displacement. The engine started with gasoline and then switched to diesel. As a result, the engine had a unique appearance with the left side looking like a diesel engine with an injection pump and four fuel lines. However, the right side of the engine had the appearance of a gasoline engine with a carburetor, magneto, and spark plugs. An auxiliary combustion chamber for the gasoline operation was provided for each cylinder and after the engine was warm, the auxiliary chambers were automatically closed and the engine switched to operating with diesel fuel in the regular combustion chambers.

During the 25 years from 1935 to 1960, diesel engines for farm tractors grew in popularity as farmers recognized the advantages of a diesel engine. During 1940 and 1941, the diesel-powered Oliver 80, Farmall MD, and the McCormick-Deering WD-6 and WD-9 tractors were introduced. Large standard-tread tractors by the 1950s were available with diesel engines and for some models, diesel was the only choice. By the mid-1950s, most tractor manufacturers offered a choice of diesel, gasoline, or LP-gas engines for row-crop tractors. Diesel engines started becoming available for utility tractors by the end of the 1950s.

Larry Gay is the author of four farm tractor books published by the American Society of Agricultural and Biological Engineers. These books may be obtained from ASABE at 800-695-2723 or, click publications and then click history books.


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