Diesel accompanying UP 3985 Challenger on Circus Train

I noticed some recent video of The Ringling Bros. Barnum & Bailey Circus train on Youtube. What is the reason or reasons
that there is a diesel Locomotive in the consist? I have seen the 3985 pull trains on its own. I wanted to get the correct answer from the experts, Thanks guys.





General Discussion: Locomotives, Rolling Stock and Equipment Moderator's Note:

This thread will get a better answer at the Union Pacific board than here.

One youtube of the movement may be found here

John Perkowski
Moderator, General Discussion: Locomotives, Rolling Stock, and Equipment

Dynamic braking-

There's some discussion in the YouTube comments that in one of the videos, you might be able to hear the diesel running at faster than idle- so they may have been partially faking 3985 pulling that train.

If the train was in fact running as a steam train, then the diesel was idling for dynamic braking, as well as a protect locomotive. The Circus train has to move partly for it's own sake, and partly for the sake of not clogging up the line, and if 3985 developed mechanical gremlins, it could have been cut off and the diesel would have finished the trip out.

I would hesitate to use the term "faking". It's pretty standard for modern steam programs to keep a diesel in-consist for a number of reasons, protect power being a top feature. You'll see 261 almost always has a P42 behind it.

The only case where you have genuine fakery in steam excursions was Clinchfield's #1 in the 1970's. Clinchfield #1 was a tiny 2-6-0 that couldn't get out of it's own way. Maintenance forces rigged up a throttle to control an F7B (see pic) behind the steamer to provide a significant portion of the power for the excursion trains. While one could consider this fakery, consider that the train was a Christmas train distributing presents amongst dirt-poor Appalachian towns, and the steam engine was for the benefit of the children.

Notice the 2-6-0 is dwarfed by an F7. It's tiny.

Tadman wrote:I would hesitate to use the term "faking". It's pretty standard for modern steam programs to keep a diesel in-consist for a number of reasons, protect power being a top feature. You'll see 261 almost always has a P42 behind it.

I'm not saying they shouldn't fake stuff, they should just be up front about what's providing what traction power.

I understand the reasons why UP had a diesel on that consist. They could have a legitimate steam run with the diesel in the consist, however, this would require that the diesel be idling at all times, used only for dynamic braking. Soon as they start applying traction power on the diesel, they are faking a true steam run. Given that 3985 is more than powerful enough for this run, they shouldn't need to use the diesel for power, just for dynamic braking.

For example, the Valley Railroad put a diesel on the Christmas train consist once because of a ton of icing, and, I think a sander issue on the steam locomotive. They tried as hard as possible, and were successful, in not using the diesel, letting it idle the whole way, and the steamer actually provided the tractive effort. Ironically enough, adding the diesel added a bit of weight to the train, effectively making the steamer work harder on the grade back up to Essex.