Locomotive #1 is an unusual combination. Virtually all internal combustion locomotives are diesel-electrics, powered by a diesel prime mover driving a generator which in turn drives one or more electric traction motors; apart from some diesel-mechanical and diesel-hydraulic locomotives. All of the major manufacturers had discarded the use of gasoline engines by the middle 1930s in favor of diesel, primarily on the grounds of fuel economy. Vulcan continued to produce a very limited number of both while it also continued to produce steam locomotives. In early 1942 it is likely that war needs made it easier to get a gasoline engine than a diesel because a gasoline engine uses much less material.
