The 11/07 issue of "Trains" has an article about an MRL tank train that stalled on a hill. The crew disconnected the MU cable and ran the two units independently to get the train up the hill with no problem.
Why would that work? Total horsepower, weight, etc is the same. And if the lead unit is in a certain throttle position, aren't all the trailing units in the same throttle position when MU'd? Thanks.
Even locomotives of the same model can handle differently.
Running the locomotives independently means each can be run where at a level where it is contributing the most - not slipping drivers being a key consideration.
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nucat78 wrote: The 11/07 issue of "Trains" has an article about an MRL tank train that stalled on a hill. The crew disconnected the MU cable and ran the two units independently to get the train up the hill with no problem.Why would that work? Total horsepower, weight, etc is the same. And if the lead unit is in a certain throttle position, aren't all the trailing units in the same throttle position when MU'd? Thanks.
Excellent question. I noticed that and also wondered, but had forgotten about it. Glad you brought it up.
~Rick
nucat78 wrote:The 11/07 issue of "Trains" has an article about an MRL tank train that stalled on a hill. The crew disconnected the MU cable and ran the two units independently to get the train up the hill with no problem.Why would that work? Total horsepower, weight, etc is the same. And if the lead unit is in a certain throttle position, aren't all the trailing units in the same throttle position when MU'd? Thanks.
The answer is in your last sentence, When the MU cable is plugged in all the locomotives will be in the same throttle position unless one of them has been shut down or isolated. The problem was this, the rail had become very slippery, and the lead locomotive could not be operated with the throttle in the #8 position without its wheels slipping badly. The story doesn't say how much it had to be reduced to stop the slipping, but let's say it was to throttle position #6. With the lead locomotive's throttle in #6 and the cable plugged in the second locomotive's throttle would also be in position #6. This didn't produce enough power to keep the train moving. By unplugging the cable the second locomotive's throttle could be in position #8, while the lead locomotive's throttle was in position #6, this produced more power which was enough to get the train up the hill. The passage of the lead locomotive with it's sanders on will make the rail less slippery for the following locomotives.
Found the answer here!
Thank you, gentlemen.
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