The Baldwin VO660 was the builder's first diesel switcher model, debuting in 1939 along with its more powerful cousin the VO-1000. It somewhat resembled models being produced by both the American Locomotive Company (its S series) and the then Electro-Motive Corporation (which produced models like the SC, SW, NC, and NW). The Baldwin Locomotive Works was never a particularly strong manufacturer of diesels. Moreso than even Alco, Baldwin continued to hold on to the belief that steam would never be replaced in main line freight and passenger service. Because of this philosophy the company never bothered to seriously research and develop such a locomotive despite the fact that EMC had already successfully demonstrated its EA and FT models.
Today, a few examples of the VO-660 remain preserved; Wyandotte Terminal #103 is located at the Illinois Railway Museum while Standard Steel #6712 is currently being put back into operation by short line SMS Lines (which loves Baldwins and rosters several in active service).
The Baldwin VO660 began production in April, 1939 as the company's first true diesel model. The company was able to produce its own line of diesels only after it had acquired the I.P. Morris & De La Vergne company, which specialized in the design and construction of diesel engines. Interestingly, Baldwin's purchase of the company was more to diversify its holdings in offering switcher and light duty diesels, as it saw no need to develop a main line freight or passenger locomotive. This can also be seen in its 1929 purchase of the Whitcomb Locomotive Works, which dated back to the late 19th century. Whitcomb had begun specializing in electric/diesel-electric locomotives as early as 1914 and after Baldwin's purchase continued to release small, industrial size switchers that actually sold relatively well.
Despite Baldwin's later issues of remaining competitive in the diesel market, like Alco it actually found quite a bit of success with small switchers. The company built three demonstrators to give railroads an idea of what the VO660 had to offer which included #335, #336, and #337. The model was a four-axle (B-B) design that was just 46 feet in length and weighed 122.25 tons. Also like Alco, Baldwin relied on Westinghouse for many of the switcher's internal components such as its model WE362 traction motors and air equipment (brakes and compressor). With a starting tractive effort of 49,625 pounds and 34,000 pounds continuous the Baldwin VO660 was quite adept at pulling almost anything asked of it. The classification Baldwin gave for the VO660 was rather straightforward.
The "VO" was the designation De La Vergne gave to the prime mover used in the locomotive and the "660" simply regarded the horsepower. The company kept this setup through the VO1000 but soon after changed its classification system to a complex set of numbers and letters. While Baldwin only sold a little over 100 VO660s railroads tended to favor the design, as could be seen in later models that sold several hundred units. Class I railroads like the Denver & Rio Grande Western, Chicago & North Western, New York Central, Northern Pacific, Western Maryland, Reading, Wabash and others all purchased at least a few units of the VO660. The relatively good reliability of the small switcher and its rugged pulling power made it a real favorite among crews and railroads.
The locomotive also found an interest with industrial settings as companies like the Iowa Ordnance Plant, American Smelting and Refining Company, American Steel and Wire Company and even the US Navy and Westinghouse itself purchased the VO660. For Baldwin its real successes with switcher designs came later with models like the VO-1000, S12, and DS-4-4-1000. These locomotives offered much greater horsepower and tractive effort, which made them more marketable (as railroads could employ them in a number of different applications, not just switching and shuffling cars). Finally, for more information about the VO660s please refer to the chart above.