Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

B-B vs Bo-Bo

999 views
11 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    May, 2019
  • 11 posts
B-B vs Bo-Bo
Posted by BEAUSABRE on Tuesday, August 20, 2019 2:19 AM

I know that under the AAR code B-B indicates a locomotive with two axles in two trucks, with a seperate motor for each axle. But I have a vague memory, possibly going back to a Trains Mag "All Diesel" issue around 1964 of there being Bo-Bo, indicating side rod (GE 45 tonner) or jackshaft drive (PRR DD1). Note this is not the European usage where Bo-Bo equals the AAR's B-B. I haven't been able to locate it on the Net, can anyone point me in the right direction?

  • Member since
    December, 2001
  • From: AU
  • 581 posts
Posted by xdford on Tuesday, August 20, 2019 7:23 AM

Being in Australia, we are used to US derived locos but European/British nomenclature for wheel arrangements.  So a 6 axle F unit would have been either Co-Co or A1A-A1A in my local area. 

North American nomenclature is explained  in https://en.wikipedia.org/wiki/AAR_wheel_arrangement  but there is no reference to Bo-Bo locos as you describe them. 

C-C would mean here and in Europe that there are 6 axles on two trucks but the wheels would have been coupled either by siderods or a single electric motor and cardan shafts. 

Having said that, there was a move (shortlived) to refer to say 2-8-8-2 locos as being 2-8+8-2 with the plus to signify articulation and there may have been a move to similarly change nomenclature for such diesels as the 45 tonner but in Wiki it is described as being B-B,

Good luck with the search!

 

Cheers from Australia

Trevor

 

 

  • Member since
    October, 2001
  • From: OH
  • 16,918 posts
Posted by BRAKIE on Tuesday, August 20, 2019 8:43 AM

There was a small move to use Bo-Bo,Co-Co and 2-6 plus 6-2 but,it finally faded away to which I said good riddance to a bad idea from yet another "expert" that wanted to change what was and still remains.

Larry

SSRy

Conductor

“Shut one’s eyes tight or open one’s arms wide, either way, one’s a fool.” Flemeth-the witch of the Wilds.
  • Member since
    February, 2002
  • From: Mpls/St.Paul
  • 11,193 posts
Posted by wjstix on Tuesday, August 20, 2019 4:25 PM

xdford
So a 6 axle F unit would have been either Co-Co or A1A-A1A in my local area.

In most areas, a six-axle F-unit would be an E-unit. Wink

Stix
  • Member since
    December, 2001
  • From: AU
  • 581 posts
Posted by xdford on Tuesday, August 20, 2019 7:48 PM

wjstix

 xdford

So a 6 axle F unit would have been either Co-Co or A1A-A1A in my local area.
 

 

When F units were marketed in North America, EMD had an option for areas in the world ... notably mine among them ... where there was a conservative limit on axle loading and therefore had an option of A1A-A1A then Co-Co (C-C) trucks after 1952.  

The F was for Freight or Fifteen Hundred HP ( some sources differ on this) whereas the E stood for Eighteen (that one seems universal). 

Our local units had a single 16 cylinder 567 (as do F's of varying horsepower) whereas E's had two 12 cylinder 567's. The smaller loading gauge meant also a rearrangement of the radiator areas on our units (106 examples over 3 systems - Commonwealth, Victoria and New South Wales) as well as a number built here for Pakistan and I believe India had a few examples also.

That's my perspective anyway,

Regards

Trevor

 

 

  • Member since
    February, 2008
  • From: Potomac Yard
  • 2,046 posts
Posted by NittanyLion on Wednesday, August 21, 2019 10:23 AM

BRAKIE

There was a small move to use Bo-Bo,Co-Co and 2-6 plus 6-2 but,it finally faded away to which I said good riddance to a bad idea from yet another "expert" that wanted to change what was and still remains.

 

The + note wasn't an add on at a later point. Whyte included it himself when he devised the system. It marks the articulation in articulated locomotives. 

  • Member since
    August, 2015
  • 214 posts
Posted by Autonerd on Saturday, August 24, 2019 8:20 PM

BEAUSABRE
But I have a vague memory, possibly going back to a Trains Mag "All Diesel" issue around 1964 of there being Bo-Bo, indicating side rod (GE 45 tonner) or jackshaft drive (PRR DD1).

AFAIK the AAR designations for locomotive wheel arrangements does not differentiate between different methods of powering axles. If a truck has two driven axles, it's a B, no matter if there is one motor or two. A four-axle, four-motor GE 44 tonner and four-axle, two-motor 45-tonner are both classified as B-B.

In Europe, as I think you know, they do differentiate; the 'o' means motors on all axles. So The four-axle, four-motor 44 tonner (or F7 or GP9) is a Bo-Bo (technically Bo'Bo') while a two-motor side-rod 45-tonner is a B'B'.

It's possible someone at trains realized this is a splendidly good idea and tried to reproduce it (though if the called a GE 45T a Bo-Bo they were doing it wrong). But officially, nope, we don't differentiate.

To beat this dead horse a little further, a PRR DD1 is a 2-B+B-2 on both sides of the Atlantic, but a GG1 is a 2-C+C-2 here and a 2-Co+Co-2 over there.

Aaron

  • Member since
    August, 2015
  • 214 posts
Posted by Autonerd on Saturday, August 24, 2019 8:25 PM

xdford
The F was for Freight or Fifteen Hundred HP ( some sources differ on this)

The sources that differ are wrong. :) F stands for Fourteen, a rounded-up figure of the FT's 1350 horsepower rating. You are correct that E stood for Eighteen, the EA's original horsepower.

Another common mistake: SW does not stand for switcher. The original nomenclature for EMC/EMD switchers were Six or Nine hundred horsepower, Cast or Welded frame -- so SC, SW, NC, NW.

Eventually the cast frame was dropped, though how the S designation stuck is beyond me -- my guess is that SW looked a lot like switcher, which made sense in the context of other model abbreviations (BL, GP, SD, MP). GM continued to offer two switcher models, high and low horsepower. Imagine if the high-HP name had stuck and we were all modeling NW1500s...

Aaron

Aaron

  • Member since
    December, 2001
  • From: AU
  • 581 posts
Posted by xdford on Saturday, August 24, 2019 11:31 PM

I am quite prepared  to be wrong - I am on the other side of the Pacific - but the auxiliary generator would have (possibly) been 150 HP thus the diesel motor would have been 1500 HP.

Having said that, you have jogged my memory and I seem to have read what you state to be the case with the 1400 HP being rounded up from 1350.  Our first Commonwealth Railways GM class loco was 1500HP output and I think that was an "at the rail" figure but I will check...

Cheers from Oz

 

Trevor

 

 

  • Member since
    September, 2003
  • 8,227 posts
Posted by Overmod on Wednesday, August 28, 2019 10:43 AM

wjstix
In most areas, a six-axle F-unit would be an E-unit.

But only if it had two prime movers... WinkWink

Now, more seriously, we have "E units" that have been re-engined with turbo 645s to make them "A-1-A F40PHs" or whatever.  

You could say, therefore, that a six-axle cowl-body "F unit" could be an E10 (or whatever UP et al. calls them) ... but then we have the whole FP45/SDP40F/F40C issue, ALL of which are C-C and were marketed/sold as passenger replacements for E-units.

And of course, trust the Australians to have a cowl-body locomotive on six axles with a bulldog nose! 

  • Member since
    December, 2001
  • From: AU
  • 581 posts
Posted by xdford on Friday, August 30, 2019 4:13 AM

Overmod
...And of course, trust the Australians to have a cowl-body locomotive on six axles with a bulldog nose! 

Actually I am of the belief that Amtrak also wanted such units in appearance but EMD would not supply bulldog noses with the SDP40F, so they became a slightly different F45 body. The last CL class was built in 1972 by local licensee Clyde which was the last in the world with the Bulldog nose.  

The Commonwealth Railways as the recipient of the class preferred the full width for pressurisation purposes to keep out desert sands crossing the Nullarbor Plain as they did.

This is CL14 in its original form ... this and the followon CLP passenger rebuilds were in my opinion the most beautiful units in Australia 

https://drive.google.com/open?id=1BX7qNsA8XWiK6iNn58XpX8cgmE4NcWsP

Cheers from Australia

Trevor

  • Member since
    September, 2003
  • 8,227 posts
Posted by Overmod on Friday, August 30, 2019 7:00 PM

NittanyLion
The + note wasn't an add on at a later point. Whyte included it himself when he devised the system.

He most certainly did not.  Lionel Wiener used it to show formal frame articulation as part of Articulated Locomotives, and LeMassena tried adopting it from there, I think in part because he was involved with the 1970 Kalmbach reprint.

Incidentally the "Bo" convention has never meant anything but separate axles in the entire time I've been reading Trains Magazine (which is since about 1963).  This leads me to wonder if someone proposed a different convention for coupled axles on things like 45-tonners, or for axles connected by Cardan shaft as on the Krauss-Maffei Amerika-Loks, perhaps with the letter 'c' for coupled or conjugated which might look like an 'o' to the unwary.

Since there are so very, very few locomotives that conjugate axles in trucks, there was never much reason to use the subletter convention 'o' in American practice.  It looks strange more because it's unfamiliar than because it's worse or undesirable, but I suspect most railfans will simply think it at least as pedantic as using the "+" for Mallet-style articulation. 

 

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!