Kelly Anderson posted:Kelly Anderson posted:I (dimly) recall reading in an operator's manual for GP35's, that engineers were advised to avoid using Run 5 as much as possible. Is that correct, and if so, why?
"For proper traction motor cooling, the locomotive should never be operated on grades below the 5th throttle position."
This quote from the helper/pusher thread must be what I was thinking of. I would assume that below the 5th notch, slower engine RPM results in less traction motor cooling air. Is that it?
Correct. With the advent of the GP20/SD24 and the GP30, the traction motor & main generator blower was mechanically driven off the engine rear gear train. Thus, the slower the engine RPM, the less cooling air for the main generator and traction motor blower.
