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Re: humor: tesla power supply

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 07:16 AM 9/21/2006, you wrote:

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi Drake,

Funny that you should mention that as I was watching the History
Channel special on freight trains last night with a fellow co-worker
and I brought up that very question myself (the one about why
trains use diesel motors to turn generators to run electric wheel
drive motors). Seems like a lot of oppurtunity for loss of energy
efficiency, dosen't it? The only possible explanation that I could
come up with is that the required power transmission to deliver
that much power directly from the huge locomotive engine to
the wheels would be impractically massive.? Any other possible
explanations?
The diesel engine:generator: motor provides the equivalent of a continuously variable transmission. 

You can run the diesel engine at one speed, where it's most efficient.
And, unlike a steam engine, which has torque at stall, this is not true for a diesel, so you'd need some sort of clutch or torque converter, which at locomotive scale would be something to see.
Large construction equipment uses hydraulic pumps and motors to do the same function as performed by the electrical generator:motor in the locos, for the same reason.