Probably covered before, but I recall reading somewhere that units like E and F diesels were usually arranged as A-A, A-B-B-A, which reduce the need to turn the locos at the end of the route (if the two or four were to be kept together). I have some Es and Fs and realize I may not know when my lashups may not be prototypical, or perhaps at least rather unusual. I presume that if 3 units HP were needed a A-B-A lashup would be not unusual. But how about:
- A-B only, which has a turn-around requirement (but "looks" nice in a passenger train, which the RR might not care about
- A-B-A-B, both A units facing forward
- A-A lashup, both facing forward
- etc
- Thinking about it, I guess the question equally applies to hood units, whether Gp7 type or the later low hood types, as the RR at the time had a standard for the long or short hoods (earlier years) forward
Thanks for any info.
Paul
Modeling HO with a transition era UP bent
All arrangements are possible, and fairly common. But there are occasional exceptions, such as the CPR which never had MU connections on the nose of an A-unit. Still, a unit being hauled dead might be found behind a trailing A-unit. In the earlier days there would have been more effort to keep the appearance as intended, especially in passenger service.
So would a (UP) E6 passenger unit A-B-A be at all common, needing 3 units HP? I have a smallish layout, and a 4-unit consist would be a bit much.
A-B only on passenger trains is fine because the whole train needs to be turned because nobody wants to ride in a car facing backwards all the way from Los Angeles to Chicago.
A-A-B is used when an extra locomotive is added to an A-B lash. It is added to the front so it doesn’t need to be cut it. This is usually on passenger trains when an extra helper is needed for a grade. This unit might have a separate crew.
A-A Having two A units pointing the same direction is not good because the crew can not move between units.
A-B-A with A units facing opposite directions is the best for freight because there is an A unit on both ends which means the locos don’t have to be turned.
j..........
cx500But there are occasional exceptions, such as the CPR which never had MU connections on the nose of an A-unit.
The SOO was another road which did not have connections at the nose of its F units.
Jim
peahrens So would a (UP) E6 passenger unit A-B-A be at all common, needing 3 units HP? I have a smallish layout, and a 4-unit consist would be a bit much.
From looking at a lot of UP passenger diesel consists, three units are certainly common. And it seems a coin toss whether they were ABA or ABB. The UP rarely ran "funny" passenger loco consists. Meaning things like AAA. Or an ABA with the trailing unit turned. Or AAB.
I believe someone said recently (can't recall exactly where) that one E unit per 5 cars is the "rule" (note quotes). Which also, approximately, fits with what I see.
There are always exceptions, of course. For example, an extra unit could be added simply as a power move.
Ed
Lone Wolf and Santa Fe A-A-B is used when an extra locomotive is added to an A-B lash. It is added to the front so it doesn’t need to be cut it. This is usually on passenger trains when an extra helper is needed for a grade. This unit might have a separate crew.
A classic example of this was NP's:
The North Coast Limited was typically lead by an ABA consist. EXCEPT that another A was frequently added on the front as a helper over the bad spots. This was so common that I bought an extra Athearn A unit for just such a consist. It ain't pretty, but it was real.
Now, the Great Northern simply ran a typical ABBA all the way. I think this was partly because their grades were a bit gentler. And their train a bit heavier.
All the above were F's, not E's, by the way.
And, anything goes on freight trains, especially later, EL trains come to mind readily, where you could see an C425, GP35, F-B unit, GP9 combo, or other "unusual" lash-ups.
Ricky W.
HO scale Proto-freelancer.
My Railroad rules:
1: It's my railroad, my rules.
2: It's for having fun and enjoyment.
3: Any objections, consult above rules.
And here, folks, is a GP9B in the lead (probably not for very long!):
http://www.rrpicturearchives.net/showPicture.aspx?id=238466
From the prototype for everything dept. Southern Pacific A-A-A-B because in California we can't be normal so we do whatever we want. lol:
Lone Wolf and Santa Fe From the prototype for everything dept. Southern Pacific A-A-A-B because in California we can't be normal so we do whatever we want. lol
From the prototype for everything dept. Southern Pacific A-A-A-B because in California we can't be normal so we do whatever we want. lol
Yeah. I recall getting on a train out of Berkeley with 5 PA's and a PB. And 26 cars.
A couple thoughts re F-units:
The original F-unit, the FT, didn't originally have a provision for couplers between the A and B units, only a drawbar. Railroads could order them as A-A back to back sets, or later an "FTSB" (FT Short Booster") could be added for an A-B-A set with drawbars. Santa Fe wanted all units separate, and EMD rigged up a way to replace the drawbars with couplers. All later F units were made to be able to have couplers at both ends.
FTs could only have a steam boiler (for passenger train heating) in the B unit. Later F's could have a steam boiler in the A unit. but there was only room for I think 300 gal. of water - not very much. So generally passenger F B-units were the ones with steam generators, since they could hold around 1200 gals of water (in the area where the cab would be in an A unit). So except for short-haul commuter trains, an A unit by itself would be rare, A-B sets would be more common - even on a passenger train with a few cars.
A-B sets of F's generally fit on the turntables of any fairly large roundhouse complex, so could easily be turned...that is, if you had a turntable big enough to turn a 4-8-4 with a six-axle tender, it was also big enough for the F3 A-B set that replaced it.
Some railroads - Soo Line would be one - only had m.u. connections in the rear of their A units, so if you had two A units in a consist they had to be on the outside of the consist and facing away from each other. You could have B units or GPs or whatever in between, but F A units had to be on the outside facing away from each other.
wjstix Later F's could have a steam boiler in the A unit. but there was only room for I think 300 gal. of water - not very much.
Later F's could have a steam boiler in the A unit. but there was only room for I think 300 gal. of water - not very much.
That was my impression, too. But the comment about FT boilers got me looking through a GN diagram book. And I happened on a diagram for 275A, an F3A. Boiler water capacity is 1466 gallons. Fuel is still the typical 1200 gallons. There is no indication where they placed that water.
Thanks, all! Most informative.
7j43kThe UP rarely ran "funny" passenger loco consists. Meaning things like AAA. Or an ABA with the trailing unit turned. Or AAB.
or ABBBB (ski trains).
MEC (Maine Central) ran F3A-F3B-GP7-GP7-F3A consists with F3A-GP7 pusher over their Mountain Subdivision in NH and w/o pusher on long potato trains from Bangor to Portland.
With the FT drawbar problem, a coupler was an option or modification that could be made to the FTAB set. Boston and Maine didnt need ABBA sets for their typical freight run. They solved this problem by ordering single FTAs (EMD changed this order to F2As when FT production ceased) to make FTA-B-F2A sets to break up the FT ABBA sets that BM was running during the war years (was infact the plan all along, however they (BM) was required to order standard sets by WPB).
7j43k And here, folks, is a GP9B in the lead (probably not for very long!): http://www.rrpicturearchives.net/showPicture.aspx?id=238466 Ed
No worse view than a long steam locomotive.
Now that is "long hood forward"!
I happened onto that photo (with the B unit) about the time Athearn announced their GP9B in PC. Well, I had gotten a PC Bowser C-430, and I had been wondering what I should do for a second unit. Problem solved!!