EMD NW

The EMD NW represented a significant transitional moment in American diesel locomotive development, being among the first switcher models to employ the newly developed EMD 567 prime mover rather than the older Winton 201-A engine that had powered earlier units in the N series family. The designation itself reflected the locomotive's origins within the broader Electro-Motive naming convention, with the letter N denoting nine hundred horsepower output and the W indicating a fabricated, welded underframe rather than the cast underframe that distinguished the NC variants. Only seven examples were constructed between 1937 and 1939, making the NW one of the rarest products of the early diesel switcher era and something of a footnote compared to the far more commercially successful S series locomotives of the same period. The NW emerged at a time when Electro-Motive, which became a formal division of General Motors in 1941, was actively refining its switcher offerings and transitioning its power plant technology. The 567 engine represented a considerable engineering advancement over the Winton products it replaced, offering improved reliability and maintainability that would become hallmarks of EMD's commercial dominance in subsequent decades. The small production run of the NW suggests it served largely as a proving ground for this engine in the switcher application, bridging the gap between the Winton-powered units that preceded it and the far more numerous SW and SW1 models that followed and went on to be purchased by railroads across the country in very large quantities. The NW's legacy lies less in its own numbers than in what it represented as a stepping stone. By demonstrating that the 567 engine could be successfully integrated into the switcher platform at the 900 horsepower rating, EMD gained confidence to move forward with a standardized and refined product line. The lessons absorbed during the design and limited production of the NW contributed directly to the engineering decisions behind subsequent switcher generations, and the model occupies a noteworthy place in the lineage that eventually produced some of the most ubiquitous yard locomotives ever operated on American railroads.

The NW rode on a B-B wheel arrangement, with two two-axle trucks providing the tractive effort necessary for yard switching duties. Power came from the EMD 567 prime mover, a V-configuration engine that became the foundation of EMD's product line for many years and represented a clean break from the Winton 201-A engine used in the earlier NC and NW predecessors. Rated at 900 horsepower, the locomotive transmitted power to its traction motors through a direct current electrical system, a conventional arrangement for diesel-electric switchers of the period. The welded underframe construction distinguished these units from the cast-frame NC variants and was considered by EMD to offer manufacturing advantages as production volumes and techniques matured. Externally, the NW shared the general appearance common to the N series family, with a longer hood than the six-hundred-horsepower S series units and twin exhaust stacks positioned centrally atop the hood, a direct consequence of the V-configuration engine's geometry as opposed to the offset stacks produced by the inline Winton engines in the smaller S series machines. The relatively compact and straightforward mechanical layout made the 567-powered switcher well suited to yard environments, where reliability during repeated short-cycle operations and ease of maintenance were of greater importance than sustained high-speed performance.