ALCO RSD-1

The ALCO RSD-1 was a 1,000 horsepower diesel-electric road switcher built by the American Locomotive Company that rode on three-axle trucks in a C-C wheel arrangement. It was often used like its four-axle counterpart the RS-1, but the six-motor design gave better tractive effort at low speeds and a lower weight per axle, at the cost of poorer performance at higher speeds. It was developed to supply the Soviet Union over the Trans-Iranian Railway from mid 1943. The first 13 units were RS-1s requisitioned by the US Army and rebuilt, and seventy were shipped to the Soviet Union in 1945, where they were classed DA20 and became the basis of the Soviet TE1, TEM1 and TEM2 diesel locomotives.