Southern Pacific 9010 - Purpose and Service As A Locomotive

Purpose and Service As A Locomotive

SP 9010 was delivered as part of the second order of ML 4000 C'C' units in the Spring of 1964, road numbers 9003-9017. (ML: Mechanical Locomotive; 4000: net horsepower; C'C': two powered bogies/trucks with three connected axles each.) The first order of six locomotives -- three for SP and three for the Denver and Rio Grande Western) -- were called "Prototypes" by KM, but were popularly known in the U.S. as "cab units" due to their fully enclosed car bodies, similar to the EMD F-unit. SP 9010 was a member of the second production order of fifteen locomotives. These were called "Series" units by KM, but were popular known as "hood units" after the more modern narrow-hood carbody with external walkways. SP's stated motives for ordering the German-manufactured locomotives were a desire for more power per axle, better adhesion to the rails, freedom from electrical malfunctions, and fewer locomotives in 'consist' than the available American diesel-electric locomotives of the time. SP owned a total of 21 ML 4000 C'C' locomotives, and a total of 24 of the diesel-hydraulic type. ML 4000s were originally used in freight service on SP's famous Donner Pass line over California's Sierra Nevada, as they were originally intended to replace the EMD F7, and had a special track set up at the Roseville locomotive shops specifically for servicing the locomotives, with German mechanics and supervisors from K-M taking U.S. residence. However, the locomotives were found unsuitable in mountain service after extensive testing and relegated to service in the flat territory of the San Joaquin Valley, often running in tandem with EMD F7s or EMD GP9s.