EMD SD38

The EMD SD38 was a six-axle diesel-electric road switcher produced by General Motors Electro-Motive Division between May 1967 and October 1971. The locomotive emerged during a period when EMD offered customers a broad spectrum of power options within its 645-series platform, allowing railroads to select models tailored to their specific operational needs. With a rated output of 2,000 horsepower, the SD38 occupied a relatively modest position in the SD-series lineup, appealing to operators who prioritized reliability and fuel economy over outright power on routes where heavy mainline performance was not required. A total of 52 SD38 units were sold to American railroads, with additional production destined for international customers. One unit was delivered to a Canadian railroad, four were exported to a mining operation in Jamaica, and seven went to a mining firm in Venezuela. A passenger-oriented variant designated the SDP38 was produced in quantity for the Korean National Railroad, with 40 such units completed during the summer of 1967 and originally numbered 6351 through 6390, a numbering sequence later revised to 6201 through 6240. An M variant was also constructed for Brazil's federal railway system, known as the RFFSA. Among domestic operators, the McCloud Railway was one of the smaller and more distinctive customers for the type. The SD38 was eventually succeeded by the SD38-2, an updated version incorporating the modular electrical components and other refinements that EMD introduced across its Dash 2 product line in the early 1970s. Though built in comparatively small numbers, the SD38 demonstrated that there was a consistent market for a non-turbocharged six-axle locomotive offering steady, dependable traction in specialized service environments.

The SD38 was powered by an EMD 645E prime mover, a naturally aspirated 16-cylinder engine producing 2,000 horsepower. This distinguished it from turbocharged siblings such as the SD40 and SD45, which used variants of the same 645 engine family but with forced induction to achieve significantly higher output. The locomotive rode on a C-C wheel arrangement, meaning it used two three-axle trucks, providing six powered axles in total and excellent tractive effort distribution suited to slow-speed switching and drag freight service. DC traction motors were employed throughout, consistent with standard EMD practice of the era. Structurally, the SD38 shared its frame and carbody dimensions with the SD39, SD40, and SD45, all of which required the longer platform necessitated by the three-axle trucks. The mechanical relationship to the four-axle GP38 was close, with the two models sharing the same engine and most major components apart from the trucks and frame. This commonality of parts simplified maintenance and parts inventories for railroads that operated both types, and it reflected EMD's deliberate strategy of building a coherent, interchangeable product family around the 645-series engine.