Model Railroading > MU B-B with C-C

New to the forum so a link to this topic in previous posts appreciated if it has already been discussed at length:
Are there any "issues" or problems having an MU consist with Locomotives that have C-C trucks and B-B trucks in the same consist.
I do this a lot on my layout especially since some of my B-B units are speed matched so well with neighboring C-C truck units so it makes for a smooth running consist. But I'm not sure whether this is/was common practice in "the real world". I model somewhat "modern" era, 1990's to today. Thanks!

Best way to find out is to look at photos of the real thing, but short answer is yes, you can mix C-C and B-B (six and four-axle) locomotives together in consists. Happens all the time in real life. These days, the preference is to use high-hp, six axle AC-traction units on road trains, and using older DC traction four-axle units on locals and switch jobs. However, before AC traction took hold in the late 90s, it wasn't uncommon to have four-axle units out on the road. SP and ATSF loved GP60s and equivalent four-axle GEs on hot intermodal trains, and didn't hesitate to mix them with other power.

Practices might vary from road to road depending upon era and area (which is why you should refer to photos wherever possible if you want to be totally accurate), but again, bottom line is that you can mix the two types.

Very common in the real world. Western Pacific only owned 4 axle engines, but all through the 70s they had 6 axle Union Pacific EMD and GE power, Burlington Northern EMD, GE and ALco 6 axle and 4 axle power all mixed with WP eqipment.

No issues with 4 and 6 axle units in 1/1 or 1/87 scales. Mix em' up!!

SantaFeRuss

No problem mixing units in model or real life.

Ted Curphey
Ontario, OR

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The prototype Southern would not mix B-B and C-C units in a consist if they could avoid it, usually the oddball was the last unit being ferried and not MUed .I grew up in PC territory, and they'd use whatever was available in any order. As I said, that's prototype. In the model world, it doesn't make any difference.

C-C units could handle running slower for a longer time than B-B units without burning up traction motors. Therefore, the RR's used them together on heavier drags. Once you reached a certain speed, that gain was lost and now you're just dragging around extra weight. If they simply needed power and didn't anticipate being "maxed out" where you'd need that extra low speed time to get a train going, they would mix and match according to what was fueled and ready to go. In the 80's and 90's era of lots of leased power on the ATSF and SP for example, you saw it quite often. This also explains why you usually see B-B on locals since they usually don't get long enough / heavy enough to warrant the extra traction motors.

Kalmbach's "Second Generation Diesel Spotter's Guide" (?) has a nice write-up at the end that goes into what jobs different locomotives do. It is a good read to understand why railroads ordered differrent locos for the different jobs. Once the engines are on the property, engines can appear on any train like the previous poster said.

Jim Montague
IRVINE, CA
Train and Nature photo Art

Fantastic! Thanks for all the information and photos. I'm not going to "worry" anymore about B-B C-C "mixes" and my mind is at ease!
Now back to my scenery projects since layout trackwork is tested and up and running.

The D&RGW mixed C-C with B-B diesels all the time. It very common to see for example SD45's running with GP30's, 35's and 40's. In the era of tunnel motors, those too ran with geeps regularly.

Cheers, Jim Fitch

Not that long ago I had a GP-9 leading an AC4400, looked very strange seeing the two together, and on a class 1 railroad. I'm not sure how much the little 567 powered geep was contributing to getting the train over the road, but sometimes when power is in short supply, you use what you have available.

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Finderskeepers Wrote:
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> Not that long ago I had a GP-9 leading an AC4400,
> looked very strange seeing the two together, and
> on a class 1 railroad. I'm not sure how much the
> little 567 powered geep was contributing to
> getting the train over the road, but sometimes
> when power is in short supply, you use what you
> have available.
>
> Posted from iPhone

Over 17 years ago when I lived in Milwaukee and Chicago, and the C&NW still existed we would see this regularly. On the Oak Creek coal trains a GP7/9 would lead a pair of AC4400CW'S or SD9043MAC's, because of the ATC leader system. I also caught a WB manifest out of Proviso with a BL20-2 leading a pair of SD9043MAC's. That was a sight. Talk about a midget with a pair of basketball centers....

Russ

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