SD39 Diesel Locomotive

Prototype Information

EMD produced the SD39 between 1968 and 1970 to provide a middle ground in its 645-series catalog. It utilized a 12-cylinder, turbocharged 645E3 engine that generated 2,300 horsepower. This model offered more power than the non-turbocharged SD38 but remained more fuel-efficient than the larger SD40. EMD built the SD39 on the same six-axle frame as its siblings, giving it excellent tractive effort for its size. Railroads primarily used these locomotives for heavy climbing on branch lines where lighter axle loads were necessary.

Production numbers remained low, as EMD built only 54 units for North American use. The Southern Pacific became the primary customer, purchasing 26 units to tackle steep grades and winding tracks in the West. The Santa Fe also maintained a notable fleet for similar rugged service. Because of their unique 12-cylinder turbocharged configuration, these engines featured a distinctively short engine block and plenty of room on the frame. While the later Dash 2 series eventually replaced it, the SD39 proved that a mid-range, six-axle locomotive could handle specialized, heavy-duty tasks with ease.