How to properly use B Units

Why not?

The PRR did it all the time.

But the other way E8A & E7B  .

Probably would get a better response on the Real Trains section, but I'll tell you what I know which isn't a lot.  I don't think that E and F units were really mixed like that.  F units were, especially as newer F units were delivered, cabs and boosters were mixed up as the railroads needs changed.  For example, the WP bought matching F3 in A-B-B configuration to use on the California Zephyr, but later replaced the F3A with an FP7.  Southern Pacific F units were delivered in A-B-B-A configuration, but in 1949 they decided to use the units individually so F3s and F7s were put together in whatever configuration could be put together, As on the end and Bs in the middle.

I think that each locomotive manufacturer made their MU controls proprietary in the early days, so consists would only be one manufacturer unless you got another crew for each brand, which kinda defeats the purpose of MU capability.  Though you could have Alco helpers on an otherwise EMD road, as the Alcos are worked to the scrapyard.  Then MU compatibility wouldn't matter as much.  Don't know if that actually happened but it would be possible.

All the MU controls operated each other manufacturers locos with the exception of Baldwin. The railroads hooked EMD locos to ALCO locos to GE locos to others. Baldwin was the odd one out because they used air operated MU connections rether than electrical MU controls like all the other manufacturers.

Seaboard used basically anything with everything with the exception of their FTA and FTB units:

In 1942 Seaboard ordered its first diesel freight road units. Classed as FTA-FTB sets they were permanently coupled together to combine 2700 HP. The first sets numbered 4000-4005 A units, 4100-4105 B units followed by 4006-4011 A and 4106-4111B in 1943. In 1944 units 4012-4021A and 4112-4121B arrived.

This is reason #1 I'll never buy any of the AA, ABBA, or what have you offerings from the manufacturers. Reason #2 is I don't like having things forced on me like that, the "You either take it like we offer it or you don't get it at all" philosophy.

The Baldwins did indeed have a different control system; otherwise, anything would run

with anything (the early Alco MU system was not compatible with some others; that was

rectified fairly soon). Diesels were MU'd with turbines on the UP; straight electrics

and diesels have been MU'd, I believe.

Mixing and matching was and is done all the time (GE/EMD right now); the GM&O would

run Alco PA's and FA's on passenger trains, and would run the PA's on freights with FA's toward the end of their lives. GM&O RS3's and EMD F3B's ran all over Illinois, MU'd.

But, it was typically more "efficient" in most ways to match the operating characteristics

of the MU's locos, so many roads had a policy of compatibility when possible, and

mixing when necessary. The Southern Railway and/or NS even instituted a policy of

not running 4-axle and 6-axle power together when possible, as the differing dynamics

was less than ideal.

All of which really makes one appreciate what is going on in the photos of a long,

heavy train with two Mikados on the front and two 2-8-0's on the rear being "MU'd"

by skill, touch, sound and whistle. Hot d**n!  

Why not?

The PRR did it all the time.

And don't forget that lone PB1 matched with E8's or e7's!

When all those ATSF F-unit A's got converted to CF7's, a lot of the B-units went along as boosters. The B-units also tagged along with some geeps.

Sometimes a steam generator B was placed on the consist of a passenger train because:

1.  The other units did not have steam generators.

2.  The train needed more water for the steam generators.

3.  The train needed more steam generators due to train length and/or weather conditions.

On the PRR passenger diesels generally were delivered with higher speed gearing than road freight units.  As passenger service declined in the later half of the 50's the PRR regeared less reliable ALco, Baldwin, and FM  passenger units for freight or helper service. I don't recall seeing pictures of PRR EMD E's MU'd with EMD F units - perhaps due to gearing differences.  There are photos of ALco, Baldwin, and FM passenger unit MU'd with freight units.  When ALco PA1 units were assigned to helper, freight, and local passenger service, PB1's remained in mainline passenger service MU'd with EMD E7's and E8's for awhile longer. 

Ed Rappe

Pennsy FP7 mu'd with a hood unit

Don't forget those Rock Island units - they just put a headlight and some windows on one end, and off it went.

Wow! Was it really that simple?

Rock Island had these unique AB6 units ...

They were built for the Rocky Mountain Rocket passenger train, which travelled as a unified train from Chicago, Illinois, to Limon, Colorado, but then divided; with one segment going to Colorado Springs, Colorado, and the other to Denver, Colorado. The Rock Island desired a locomotive that could look like an integrated part of the train during the Chicago-Limon portion of the route, but could then be operated independently to take three cars to Colorado Springs.

http://en.wikipedia.org/wiki/F...k_Island_AB6_750.jpg 

In later years Rock island converted some cabless E units by adding home-made "Crandall cabs". These "E9BS" units were later owned by CNW and used in Chicago commuter service.

As for the question about mixing E units and F units: E units had two V12 engines for more power, but only 4 of 6 axles powered, which made them better suited for fast passenger trains on flatter terrain. E units were typically geared for higher speeds. F units had a single V-16 engine with all four axles powered and were more typically used for freight, less total HP per unit but more tractive effort at slower speeds. Some railroads like AT&SF used F units for passenger trains that encountered serious grades like Raton Pass. FP7 and FP9 locos had a longer frame to accomodate a steam boiler and water tanks for train heating.

E and F units had compatible MU controls, but mixed consists would have had mismatched low-speed ratings. In later years when some railroads had a surplus of E-units due to reductions in passenger train services, they sometimes used them for freight service.

For modelling purposes you can do whatever you want if it looks good to you. Something to upset the rivet-counters.

Three railroads which regularly mixed EMD E-units and F-units on passenger trains were the Milwaukee Road, Kansas City Southern and Katy.  Missouri Pacific mixed E-units and GP7's, and also mixed Alco-GE PA's with EMD E's..

Union Pacific and (occasionally) Santa Fe mixed PA-1, PB-1 and Fairbanks-Morse Erie-Built units.

Southern Pacific mixed ex-T&NO and Cotton Belt PA-1's with E7 A's and B's on its Coast and Sunset Routes.  (None of these units had dynamic braking.  The one-owner Southern Pacific PA and PB units had dynamic braking and were not intermixed with EMD's.)

On freight, railroads did not usually mix Alco-GE RS2's and RS3's with EMD GP7's and GP9's if the railroad used dynamic braking.  However non-DB units of those types were often seen mixed on some railroads.  There was a dynamic brake control difference between first-generation EMD's and Alco-GE's.

The Crandall's were built by the C&NW, not the Rock Island.

http://www.american-rails.com/crandall-cabs.html

Rusty

Thank you for all of the replies - seems like the practice really varied from one line to the next!

David

GM&O E7-F3B-E7

http://www.railarchive.net/gmogallery/photo021.htm

GM&O E7-F3B-F7A

http://www.railarchive.net/gmogallery/photo014.htm

A great site for GM&O fans

Dan

Also Missouri Pacific

From Mike Conderen's great site

http://condrenrails.com/MoPac/MoPac_Loco_Pixs.html

GP7-E8-E7