Basic driving instruction....

[Ghost42]

I just love steam, but occasionally jump in a diesel.
Take the SD40, when accelerating I wait for the ammeter to back off then change up, fine so far, but how do you hillclimb, it does not seem natural to have the ammeter at full deflection.
Do you change down to keep the needle out of the red zone? or keep the revs up till the loco complains?
Doesn't seem right to have the needle in the red for long periods.
Perplexed Rog

 

[sniper297]

You don't "change up" or "change down" with a diesel, since it's actually misnamed - correct term is "diesel-electric" since the diesel engine is coupled only to a big generator and has no gears. What makes the engine move is electric traction motors, similar to the ones in electric trains and elevator ("lift") hoist motors.

In real life pegging the ammeter would probably overheat the motors and/or blow fuses, but none of the train simulators simulate that so you can run all day with the amps in the red zone.

 

[Ghost42]

You don't "change up" or "change down" with a diesel, since it's actually misnamed - correct term is "diesel-electric" since the diesel engine is coupled only to a big generator and has no gears. What makes the engine move is electric traction motors, similar to the ones in electric trains and elevator ("lift") hoist motors.

In real life pegging the ammeter would probably overheat the motors and/or blow fuses, but none of the train simulators simulate that so you can run all day with the amps in the red zone.

That last line says it all, thanks.
Rog

 

[sniper297]

Lot of it will be dependent on passenger or freight and how much G forces are allowed - example is Chicago Transit Authority elevated and subway trains, speed and keeping to schedule is priority 1, passenger comfort is the passengers problem better grab something and hang on tight. :hehe: CTA railcars in modern times don't even have air brakes because they don't need them, with every axle powered by a traction motor the dynamic braking has to be experienced to be believed. A friend and I timed it once, from full speed 60mph to full stop doors opened about 20 seconds, 15 seconds for the doors to open and close, 20 more seconds back to full speed at the average stop. For a regular passenger train you might start and stop more smoothly, for a heavy freight you have "locked rotor amps" to deal with - starting current with the motor trying to get moving against the resistance of the mass it's trying to move. I suspect the fuses or circuit breakers are the "slow blow" type designed to tolerate overamperage for a period of time, since locked rotor amps can be 3 to 8 times the running full speed amps. Obviously you want to avoid that for long periods, so standard procedure would be to back up to bunch up the slack in the couplers, then pop it into notch 3 or 4 to get moving up to 5mph or so before the dead weight of the entire train loads you down. That's an art by itself, banging draft gear to the stops without doing it violently enough to bust a knuckle or taking it too easy and getting wheelslip as the full weight comes on before you have enough momentum.

As for climbing grades, probably the biggest problem and solution is the same as for steamers, wheelslip rather than overamping. Same solution, back the throttle off to zero, hit the sanders, sneak up on the slipping point and note where it is if it starts slipping again, back off again and sneak up to the notch just below where it started slipping. And of course momentum is your best friend, if you got a long straightaway before the grade crank the speed up before you hit the bottom of the grade.

 

[Ghost42]

Lot of it will be dependent on passenger or freight and how much G forces are allowed - example is Chicago Transit Authority elevated and subway trains, speed and keeping to schedule is priority 1, passenger comfort is the passengers problem better grab something and hang on tight. :hehe: CTA railcars in modern times don't even have air brakes because they don't need them, with every axle powered by a traction motor the dynamic braking has to be experienced to be believed. A friend and I timed it once, from full speed 60mph to full stop doors opened about 20 seconds, 15 seconds for the doors to open and close, 20 more seconds back to full speed at the average stop. For a regular passenger train you might start and stop more smoothly, for a heavy freight you have "locked rotor amps" to deal with - starting current with the motor trying to get moving against the resistance of the mass it's trying to move. I suspect the fuses or circuit breakers are the "slow blow" type designed to tolerate overamperage for a period of time, since locked rotor amps can be 3 to 8 times the running full speed amps. Obviously you want to avoid that for long periods, so standard procedure would be to back up to bunch up the slack in the couplers, then pop it into notch 3 or 4 to get moving up to 5mph or so before the dead weight of the entire train loads you down. That's an art by itself, banging draft gear to the stops without doing it violently enough to bust a knuckle or taking it too easy and getting wheelslip as the full weight comes on before you have enough momentum.

As for climbing grades, probably the biggest problem and solution is the same as for steamers, wheelslip rather than overamping. Same solution, back the throttle off to zero, hit the sanders, sneak up on the slipping point and note where it is if it starts slipping again, back off again and sneak up to the notch just below where it started slipping. And of course momentum is your best friend, if you got a long straightaway before the grade crank the speed up before you hit the bottom of the grade.

Thanks for the detailed reply, should be of interest to many.
Rog
Roll on TRS2020 (if I'm still around)