A lot of us railfans will remember Southern Pacific's flirtation with diesel-hydraulic propulsion back in the 1960's. It was back then and still is to a great extent the preferred propulsion/transmission system on the railroads of Europe. Personally I think that the experiment on Southern Pacific rails was doomed to failure. At that point in time the diesel-hydraulic technology was just not able to deal with the demands of US railroading.
Of course the technology problem is no longer the case: witness the relatively new Voith "Maxima" diesel hydraulic locomotive. Take a look at some of the technical specifications of this series of locomotives:
Mass (incl. operating fluids): 126 to 135 tonnes
Length across buffer: 23.2 meters
Maximum speed: 120 km/h (160 km/h approved)
Diesel engine output: 3600 kW (4850 hp)
Tank volume: 9000 liters
Operating tractive effort at μ = 0.33: 408 kN
More information about the "Maxima" is here.
Here then is a story about the only remaining Southern Pacific diesel-hydraulic locomotive. This is from Trains Magazine, 01 October 2012:
Southern Pacific 9010, the only survivor of 15 German built Krauss-Maffei diesel-hydraulice locomotives in the early 1960's for the Souhtern Pacific, has gotten it's nose back. At 4000 horse power it was the world's most powerful six axle locomotive at the time. Retired in 1968 it was converted to a camera car. It served as a platform for filming for the world's first fixed-based full motion locomotive simulator. It was extensively rebuilt at the time, losing it's nose and of of its two 2000 hp V-16 Maybach engines.
The fact that it was converted to a camera car led to its salvation as all of its sister locomotives were scrapped. It was purchased by the California State Railroad Museum in 1986 and was the subject of an abortive effort to restore it to its originasl appearance. The locomotive sat without a nose and exposed to the elements and vandals in Sacramento until it was acquired by the Pacific Locomotive Association in 2008.
Volunteers began restoration work, which included fabricating a new nose duplicating the original. In September, the surfaces around the cab front windows were painted and the right side of the cab was coated in grey. Bee Line Glass made patterns for the two large front windows and the new glass was installed. Finally, on September26, the new nose was placed on the locomotive. t was settled into place and bolted down, then the restoration crew posed for photos.
Plans for the locomotive include a fully functioning operator's station in the cab, with the ability to control a trailing locomotive for power. In the long term the remaining engine may be repowered and returned to service, but many missing parts would have to be located and reinstalled.
For a lot more information go to www.sp9010.ncry.org
Click here for a short discourse on locomotive propulsion.