Unique US diesel hydraulic runs again
FOR the first time in decades the sole surviving German-built diesel hydraulic loco built for use in the US by Southern Pacific (SP) was fired up in late August. The loco, ex-Southern Pacific No. 9010, has been under restoration at the Niles Canyon Railway in California since 2008.
Parts have been sourced from all over the world, including the Diesel Traction Group in the UK. The SP locos were powered by the Maybach engines as used in the various BR WR diesel hydraulic designs. No. 9010 only has one working 2000hp Maybach MD870 engine (as used at a lower power rating by BR Class 35 ‘Hymek’ locos) but that will be sufficient for operation in the future.
After six prototypes were delivered from Krauss Maffei in Munich (nowadays Siemens owns the Munich Allach factory) in 1961 – three to SP and three to Denver & Rio Grande Western (later bought by SP) a further 15 production type ML4000 locos were built in 1964 for SP. No. 9010 is one of these production locos and the sole survivor. SP wanted to use diesel hydraulic locos as they offered much more power (two 2000hp MD870 engines per loco) than contemporary North American locos and using direct gearing did not have traction motors. However, operating experience soon showed they were much more expensive to maintain and after just five years all were withdrawn.
No. 9010 was withdrawn in September 1968 and survived as a camera-equipped trailer used to capture driver training films. When built, the locos featured cast bogies and these were made in England as Krauss Maffei did not have a German supplier which could produce them (its locos for European railways used fabricated bogies).
Many years later, the bogies now under No. 9010 would return to California via the UK too as they had been sold by SP when the rest of the locos were scrapped and a pair ended up under a track machine operated by Colas in France.
When it was scrapped, the bogies were shipped via Southampton to San Francisco.