[Vroomfondel]

The idea has been around for a very long time. For example, one of Ferdinand Porsche's very first projects, way back at the beginning of the 20th century, was a hybrid with motors in the wheels.

According to some old train books that I found in an old book store, diesel-electric locomotives liked to run at 800 RPM. I don't know if that's still true...

[Fred Hayek]

The diesel engines in locomotive service run at a low rpm - 750 to 1000 rpm range, in most cases. Keep in mind that these are also high displacement engines. For example, a GM-EMD 16V-710 will run about 4000 hp using a turbocharger at that rpm range, but that's also with 710 cubic inches per cylinder. Some rail diesels run at higher rpm's, however that is either due to lower displacement (such as some locomotives re-fitted with Caterpillar engines), or the alternator is also being used for passenger train power (typically 480V 3ph in US service for modern "head-end power" rolling stock). The latter is why the F40PH's used by Amtrak and some commuter agencies sound like they are running at max rpm - constant rpm to maintain the 60 Hz. The power output for this setup is changed by adjusting the excitation on the alternator field windings and the fuel rack settings on the diesel.

[expatpat]

Thanks. I guess I was right about the lack of novelty, but wrong about the rpm.