Alco / EMD compatibility

T

TrainNut

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Sep 15, 2004
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So I was looking through my train chest and came across an old Con Cor Alco PB. I pulled it out and looked at it and thought it'd go great with my EMD F7B. I looked up the years and the PB's were manufactured starting 1946 while the F7's were manufactured starting 1949.
(That seems backwards to me. It seems like the PB should have come later than the F7B.)
Soooooo, who knows their history... For the Rio Grande, could it have been possible that they lashed a PB up to an F7A/F7B? The years are close enough. I put 'em together to see what they looked like and they don't look near as smooth as I'd hoped.
IMG_5607lowres.jpg
 
Hmmm, they definitely look better together in your pictures than they do in mine... although I suppose the black and white helps. Thanks for the info. All I have to do now is convert the couplers on the PB to match the rest of the train!
 
One thing that will help with the looks is to go to close-coupling couplers. And if you're really ambitious, you could add vestibules to the F's too.
 
a little weathering may blend them together better, and as mentioned by squidbait, some diaphragms. keep in mind that a PA was almost exclusively a passenger loco, so you need some passenger cars to go wih it :)

Kevin
 
Not so fast, guys. While the PA leading is hard evidence they worked together the PB trailing is not. Rio Grande converted two PB units to use as steam generators because F-units were not so equipped.

Compatibility isn't always a matter of locomotive builder. The brake system that railroad specifies is one of the biggest issues. In the 1970s the Rio Grande sold ten Geeps to the Rock Island. Somebody at the later wasn't paying attention and they got ten units incompatible with the rest of the fleet necessitating those units operating independently or MU-ed exclusively to each other to retirement.

I also recall a number of roads only being able to MU Fairbanks-Morse units together as they used a different control system unless specified by the purchaser. On the other hand the Wabash commonly ran consists from four builders (Alco, EMD, F-M, and GE) because they specified compatible systems for all their equipment.
 
I suspect the PB in the last photo may have been converted to a steam generator car, but being in the middle of the consist - i'm not sure. the first photo has what appears to be exhaust coming from the roof. Could be steam generator exhaust, though. The other photo with the PB it is in a 2-unit consist with a rather large train. I suspect it was still powered.

Kevin
 
nachoman said:
a little weathering may blend them together better, and as mentioned by squidbait, some diaphragms. keep in mind that a PA was almost exclusively a passenger loco, so you need some passenger cars to go wih it :)
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Yes, the lighting in my picture does not help either as the picture was taken on a mild curve and the PB was facing towards the light and so seems brighter while the FA and FB were facing away. The diaphragms idea as well as closer coupling sounds intriguing. I already have 5 like painted passenger cars and am expecting 5 more from Con Cor any day now so that's not a problem. I also use that consist to pull my Southwest Chief.

railohio said:
Rio Grande converted two PB units to use as steam generators because F-units were not so equipped.
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Yep, that was another option I was thinking of to justify its use in the train. Good info to know. Thanks everybody!
 
(That seems backwards to me. It seems like the PB should have come later than the F7B.)
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I wonder why you think that. I wouldn't normally think of those locomotives in the same breath like that, as they weren't exact competitors.
Soooooo, who knows their history... For the Rio Grande, could it have been possible that they lashed a PB up to an F7A/F7B?
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As shown above, they definitely did, and their MU and brake systems must've been compatible. Not necessarily as-built, though. Many roads modified their older non-EMD power to MU with EMDs (second-gen non-EMDs were normally compatible from the factory).
The years are close enough.
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Locos a lot farther apart in age than those will run together.
I put 'em together to see what they looked like and they don't look near as smooth as I'd hoped.
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Even passenger trains didn't always get matched consists.
 
TrainNut said:
...the PB's were manufactured starting 1946 while the F7's were manufactured starting 1949. That seems backwards to me. It seems like the PB should have come later than the F7B.
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Triplex said:
I wonder why you think that. I wouldn't normally think of those locomotives in the same breath like that, as they weren't exact competitors.
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I was relating the progression of Diesels to the progression of steam. With steam, the newer the engine, the bigger and more powerful it was (not always but usually). In this case, just by looks, the PB has three axles per truck instead of two, and is much larger than the F7B. Therefore, logically, the PB appears to be newer.... not older.
HOWEVER,
If I look at that same comparison from todays modern technological advances, it makes perfect sense. All the greatest, newest stuff is always smaller and more compact than its predecessors (not always but usually).
Clear as mud?
 
Power didn't always increase with time -- there were always applications where a less powerful loco would be more economical.
Early passenger diesels were often given 2 engines, apparently in case one failed, while freight locos went with a single.
If you went by these criteria, the GG1 would be newer that almost all the diesels, although it was older that most of them.
 
Just to clarify things a bit, re delivery dates and conversion to steam genny's...

D&RGW's PB's (all 2 of them) were delivered in February and April 1947. They were converted to steam generators in 1965. Their F7B's were delivered between 1948 and 1955.
The PA's remained on the roster until 1967, the F7's until 1968.

The converted PB's have a bit more interesting story, or at least #253. While 252 was retired in 1991 from revenue service and became a stationary steam generator, 253 went from covering the Zephyr to the ski train when the Zephyr was discontinued in 1983. In 1980 253 had its' 3-axle A-1-A trucks swapped out for EMD 2-axle Blombergs (since there was no longer a prime mover and associated hardware, the unit was much lighter). When the Ski Train was sold to a private company, they converted the unit from steam to 480V HEP in 1987. In 2000 the Ski Train was re-equipped with F40PH's with their own HEP gensets, the 253 was sold to the Algoma Central, where it now provides HEP as Algoma Central 78 for the tour trains.
 
That's true, and that "apartment building" isn't in the background, either. ;)sign1sign1

Still, yet another example of "a prototype for almost anything".

Wayne
 
Early passenger diesels were often given 2 engines, apparently in case one failed, while freight locos went with a single.
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Typically, early road freight diesels were B-B cab units of 1350-1750hp, though there were also passenger versions of these models. The passenger-specific models were A1A-A1A cab units of 1800-2400hp. EMD and Baldwin passenger diesels had two engines, but Alco PAs and FM Erie-Builts had only one.
Early passenger diesels were often given 2 engines, apparently in case one failed, while freight locos went with a single.
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Not the reason - at that time, the manufacturers in question didn't have single prime movers with enough horsepower!
 
An interesting end for the Pa's & Pb's to me was the Santa Fe's use of them to power #11 & #12 the fast mail trains. I remember a picture in either Trains or Railroad & Railfan once of a bunch of Alco Pa's & Pb's pulling the mail train where they had what looked like 6 or 7 locomotives pulling less than 10 cars!
 
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