EMD SC

The EMD SC was one of four model designations within Electro-Motive Corporation's early Winton-engined switcher line, which collectively represented a pivotal step in the dieselization of American railroad yard operations during the latter half of the 1930s. The SC designation identified units from the 600 horsepower S series that rode on underframes cast as a single piece by General Steel Castings of Granite City, Illinois, with the C in the name referring specifically to that cast construction method. Only two SC locomotives were built in 1936, making the model one of the rarest within the broader family of Winton-engined switchers, which as a whole numbered 175 units built between 1935 and 1939. These two units were part of a broader commercial effort by Electro-Motive to establish diesel switchers as reliable, economical alternatives to steam power in yard and industrial service. The 600 horsepower S series as a whole proved considerably more commercially successful than the companion 900 horsepower N series during this early period, with the combined SC and SW production totaling well over one hundred units spread across a wide range of railroads, steel companies, and industrial operators. The SC's cast underframe variant was eventually joined by the more numerous SW, which used a fabricated welded underframe and ultimately accounted for the greater share of 600 horsepower sales. The SC occupies a modest but historically noteworthy place in diesel locomotive development as part of the generation of power that preceded EMD's own 567 engine series and helped demonstrate to American railroad management that diesel switchers were a commercially and operationally sound investment. The broader family of Winton-engined switchers laid the groundwork for EMD's postwar dominance of the switcher market.

The SC was powered by the Winton 201-A engine in a straight-eight configuration producing 600 horsepower, which drove the locomotive through a DC electrical transmission system. The B-B wheel arrangement placed four powered axles under the locomotive in two two-axle trucks, a configuration well suited to the relatively light-duty switching work these units were intended to perform. The straight-eight cylinder arrangement of the Winton engine had a practical effect on the locomotive's external appearance, as it positioned the exhaust stacks offset to the engineer's left rather than centered on the hood, a feature that distinguished the S series from the N series locomotives whose V12 engines produced symmetrically centered stacks. Visually, the SC shared the characteristic hood design of the S series, which was shorter than that of the N series and featured a rounded, satchel-shaped enclosure ahead of the radiator. Small louvers positioned at the upper front sides of the hood and lifting vents along the hood top for ventilation further distinguished these Winton-engined units from the later EMD 567-powered switchers that would follow. The cast underframe supplied by General Steel Castings was structurally distinct from the welded fabricated underframe of the SW but was otherwise functionally equivalent, and the two frame types were used interchangeably beneath both the S and N series hood assemblies.