The SPRR bought diesel – hydraulic locomotives from a West German locomotive builder as an experiment. The concept of using diesel engines, as the primary power source for railroad locomotives, was relatively new in 1964 when compared to steam engines. The dominant use of the diesel engines in USA railroad locomotives was, and still is, an indirect drive design. The diesel engine drives an electric generator and the current produced is directed to axle motors to produce the tractive force of the locomotive. There is no direct mechanical connection between the diesel engine and the axles of the locomotive.
The West German Company, Krause – Maffi, followed the direct drive concept, in that the diesel engine of the locomotive was connected directly to the locomotive axles by a hydraulic transmission. I assume the SPRR decided to give the direct drive locomotive concept a try in the USA to create a realistic basis for comparison of the two concepts. How did the comparison work out? There are no direct drive locomotives in mainline service on railroads in the USA today.
The images below were made in Taylor Yard, located in the City of Los Angeles, about 1964.
Click on any image to enlarge – enjoy.