Steam & Excursion > Running a Diesel Helper with Steam Locomotive

I have seen photos and video of 4449 running with an Amtrak P42 and 844 running with the Centennial. I'm curious how this works. Do they somehow MU a steam and a diesel...or is the diesel just along for the ride as a backup in case of problems?

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EMD developed and built a diesel MU control box for the cab of 4449, at the request of Doyle McCormack, during the American Freedom Train national tour. Both the air brake and electrical power to control one or more diesel units from the Engineer's side of 4449's cab was the end result.

By plugging in a standard AAR 27 pin MU cable, to pretty much any diesel coupled to 4449's tender, or auxiliary tender, the trailing diesels are controled by the Engineer on 4449. Additional MU control boxes where subsequently made for NKP 765, UP 844 and UP 3985.

All functions of the MU'ed diesels, except for dynamic brake, are controlled from the cab of the steam locomotive,i.e. Forward, neutral, Reverse, Generator Field, throttle positions idle & 1 thru 8, indicator light for wheel slip, a red light to indicate "ALARM", and a toggle switch for emergency train line shut down.

1522 had one of your MU boxes also Jack. Came in handy several times when we wanted to get up to track speed quickly without beating the engine to death.

Does Milwaukee Road 261 have a similar MU box? I am just curious.

IIRC 261 has 26L air connections on the back of the tender, but does not have an MU throttle.

Steve has been quoted as getting on the radio and saying, "If you back there don't back off on your throttle and let me do the work, I'm going to come back and take away your reverser."

-Larry Doyle

I thought 611 also had MU controls... I know NS installed some very modern stuff in it before it was retired...temporarily, (crosses fingers).