The Baldwin VO-660 was a diesel-electric locomotive switcher built by Baldwin Locomotive Works between April, 1939 and May, 1946. The 197,520–203,980 lb (89,600–92,500 kg) units were powered by a six-cylinder diesel engine rated at 660 horsepower (492 kW), and rode on two-axle AAR Type-A switcher trucks in a B-B wheel arrangement. 142 examples of this model were built for American railroads, along with the United States Navy. Baldwin replaced the VO-660 with the model DS-4-4-660 in 1946.