EMD SD35

The EMD SD35 was produced by General Motors Electro-Motive Division from June 1964 through January 1966, representing part of EMD's ongoing effort to expand its six-axle road switcher lineup during a period of intense competition in the diesel locomotive market. A total of 360 units were constructed during this relatively brief production window, all of them destined for American railroad operators. The model occupied a middle tier in EMD's catalog of the era, offering a meaningful step up in power over earlier six-axle designs while remaining a practical and economical choice for railroads that did not yet require the higher horsepower figures that would define later generations of motive power. The SD35 entered service at a time when American railroads were actively seeking locomotives capable of handling heavier tonnage on main line assignments without resorting to multiple-unit lashing of lower-horsepower units. Its 2,500 horsepower output made it a capable if not exceptional performer, and the six-axle C-C wheel arrangement distributed weight effectively across the rail, improving tractive effort and suitability for grades and curves. Several Class I railroads acquired the model, and examples found their way into a variety of service environments across the country during the mid-1960s. The SD35's legacy is modest but noteworthy within the broader arc of EMD's product development. It served as a transitional design, bridging the gap between the earlier 567-series powered locomotives and the more powerful units that would follow as the 645 engine became the standard EMD prime mover in subsequent years. Some units survived long enough to be rebuilt and modified by subsequent owners, with at least one example converted to a different configuration entirely. A small number of SD35 locomotives have been preserved, including a Baltimore and Ohio unit held at the Baltimore and Ohio Railroad Museum in Baltimore, Maryland.

The SD35 was powered by EMD's 567D3A prime mover, a 16-cylinder version of the long-running 567 engine family that produced 2,500 brake horsepower. This engine had been refined over many years of service and was well understood by railroad mechanical departments of the period, which contributed to the locomotive's general reliability in road service. The unit rode on a C-C wheel arrangement, meaning it carried two three-axle trucks, with all six axles powered through direct current traction motors, a configuration that provided strong continuous tractive effort suited to freight hauling duties. The SD35 shared its underframe with the EMD SD28, giving both models an overall length of approximately 60 feet 8 and one half inches. A fuel tank with a capacity of 3,000 US gallons was fitted, providing reasonable range for road assignments. The use of DC traction motors reflected the prevailing technology of the era, as AC drive systems for locomotives remained many years in the future. The locomotive's general mechanical layout followed established EMD conventions, making parts commonality and maintenance relatively straightforward for shops already familiar with the builder's earlier products.

Models by: Atlas · Walthers