Diesel-hydraulic locomotives

Ask Trains from the December 2015 issue
Krauss-Maffei diesel-hydraulic No. 9120 pulls an excursion for the Pacific Locomotive Association out of Oakland, Calif., in April 1967. The same organization would later work to restore sister unit No. 9010 to operation.
Robert L. Hogan
Q What can you tell me about the Krauss-Maffei diesel-hydraulic locomotives that operated in the U.S. in the 1960s? Which railroads purchased and operated them, and what became of them? – Rod W. Gower, Adelaide, Australia

A Two North American railroads purchased the 3,540-hp Krauss Maffei model ML4000 diesel-hydraulic locomotive in two varieties: Denver & Rio Grande Western and Southern Pacific. Rio Grande and SP both purchased three cab-style unit models while the latter also opted for 15 hood unit models. Rio Grande eventually sold its units to the Southern Pacific, which retired the entire fleet by the end of 1968. While the units did not last long in revenue service, they did nudge the domestic locomotive builders to develop higher horsepower models. One unit, No. 9010, survived and was converted into a special camera-equipment car to record video for the SP’s locomotive simulator. It was later donated to the California State Railroad Museum, and then acquired by the Pacific Locomotive Association in Niles, Calif., where it is now undergoing restoration for operation. – Brian Schmidt
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