Re: diesel loco

[jcmassey@netspace.net.au]

At 10:23 PM 29/06/01 +0530, you wrote:
>But, the losses in the various stages of energy conversion would make
direct drive from the engine a more feasible
>option, at least for the initial push. Why waste so much energy?
>
>Prasad

Not wasting energy - multiplying torque, and gaining (HUGELY) reliability.
It's the problem of using a narrow power band engine or motor in a variable
speed application. You get (x) torque at (y) RPM, if you bring the engine
down to no speed, you get no power (Nature of the engine). So unless you
gear down the speed and run the engine in it's power band you go nowhere.
By gearing down to 1/10 of engine RPM you get 10x motor torque. but a CVT
at this power level? Cost++++!! It could be done with hydraulics (A tug I
did some work on had hydraulic drive). So the method used is that the
diesel generates electricity powering the motors in the wheels - an
electric CVT with extreme reliability (very necessary with trains). Some
ships use Diesel/electric, too.

James