??? F-Unit A/B (A/B/C) power combinations

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CurlSnout

Henna Gaijin
Here's a question (rather, another question) to betray my newbie status. So far I am running small trains (I favor F-units) in which there is either a single A unit locomotive or A/B units in which the B unit is unpowered (i.e., a dummy). Many locomotives are sold as A/B combinations in which both units are powered (at least one of which I am aware is offered as an A/B/C combo in which the A and C units are powered and the B is a dummy).

What I'm wondering is this: How closely do such units need to be matched, with respect to power?

It seems to me that if there is a significant disparity, then one unit would end up either pushing or pulling the other (depending on whether the "weaker" unit is leading or trailing), despite the fact that both have traction.

Does my question make sense? Is there an anwer that makes sense?

Thanks in advance,

cs
 

grande man

Bonafied Grande Nut
Here's a question (rather, another question) to betray my newbie status. So far I am running small trains (I favor F-units) in which there is either a single A unit locomotive or A/B units in which the B unit is unpowered (i.e., a dummy). Many locomotives are sold as A/B combinations in which both units are powered (at least one of which I am aware is offered as an A/B/C combo in which the A and C units are powered and the B is a dummy).

What I'm wondering is this: How closely do such units need to be matched, with respect to power?

It seems to me that if there is a significant disparity, then one unit would end up either pushing or pulling the other (depending on whether the "weaker" unit is leading or trailing), despite the fact that both have traction.

Does my question make sense? Is there an anwer that makes sense?

Thanks in advance,

cs
There's no shame in being new to something and asking questions to learn.

First off, there is no such thing as a C unit. While the CB&Q (I'm recalling your previous post) used different letters in their road numbers to distinguish the individual units, the locos themselves are either A or B units. A typical multiple unit consist might be an ABBA set, ABAA, AABA, ect.

If you are running short trains, dummy trailing units (either As or Bs) would save you some money. Are you running DCC? If so, the dummys make for easy sound conversions in their roomy shells if the trucks are set up for power (the Stewarts are).

Typically, units from the same manufacturer will run fine together on DC. DCC allows units to be fine tuned to allow most units to run well together, regardless of manufacturer.
 

sushob

Entrepreneurial Teen
Often if you match locos from the same manufacturer, they will run very well together (ie an A-B-A set of Stewart locos or two Athearn RTR engines together). There are also other combinations of different manufacturers' engines that run well together, but others here have more experience with that than I do...
 

CurlSnout

Henna Gaijin
There's no shame in being new to something and asking questions to learn.

First off, there is no such thing as a C unit. While the CB&Q (I'm recalling your previous post) used different letters in their road numbers to distinguish the individual units, the locos themselves are either A or B units. A typical multiple unit consist might be an ABBA set, ABAA, AABA, ect.

If you are running short trains, dummy trailing units (either As or Bs) would save you some money. Are you running DCC? If so, the dummys make for easy sound conversions in their roomy shells if the trucks are set up for power (the Stewarts are).

Typically, units from the same manufacturer will run fine together on DC. DCC allows units to be fine tuned to allow most units to run well together, regardless of manufacturer.

Thanks for the speedy replies. At least one of the voices inside my head knew that the "C" unit to which I made reference is/was, in fact, an "A" unit. And yes, you (grande man) were correct - I was referring back to the CB&Q A-B-A consist.

I am not running DCC. I am re-discovering the joys of running HO-scale trains, and re-capturing at least a piece of my youth (I asked Santa to bring me an electric train last December and he was good to me). For now I am running a small layout on my living room floor (confuses and entertains the cats); my dream is to someday have a house with a basement that I can haunt and run a "real" layout. DCC may come later.

Given that using dummy B units would for sure save money (for those of us running short trains), I don't really see that very many outfits offer dummy B units - Stewart so far seeming the exception, and I might start buying more Stewarts. I have an Intermountain Railway F7A/F7B (both units powered) that I purchased specifically to have this Southern Railway set (black tuxedo livery) with extra-detail (my father worked for SR for fifteen years). And I have a Walthers Trainline Alco FA and FB (both powered) in Spokane Portland & Seattle colors (hard to find SP&S locomotives) that I purchased because I wanted something representing the Pacific Northwest regardless of the (relatively lower) detail level. Finally, I have one Athearn Genesis F3A (Southern Railway, green) locomotive, which I bought because I specifically did not want a powered B unit running behind it (and it was the first locomotive I bought that - in my universe - commanded a "premium" price and at the time couldn't justify the expense of the comparable A-B set).

In any case, I'm anxious (not necessarily impatient) to get my first Stewart and see how it compares to what I have already.

Thanks again,

cs


ps: Nate I sent you another order. Thanks in advance.
 

HaggisKennedy

Coal Shoveler
Jumping in late here....

You may be confused by the fact that some RRs (maybe the "Q") numbered their loco sets with the same numbers, but appended a letter at the end. This would give you, say 456A, 456B, 456C, and 456D. This would be an ABBA set, since in those days, due to the Brotherhoods, all individual units here were to be considered one locomotive (set). This got past the rule that all individual 'locomotives' had to have an engineer and fireman, which is dumb for a "B" unit. Since the RRs bought them as a 'set' (ABBA, ABA, AA, AB), they were numbered this way. Once those union rules went by the wayside, you saw the RRs start to mix and match.

Now, for running them on the layout, most locos from the same company should run OK together. With mixing other brands, it could be hit or miss. The worst offender is the (modern) P2K SD60; it has a totally different gear ratio in the trucks, so they don't play well with anybody. But, in general, you ought to be OK.

One tip: If you have two closely matched locos, put the faster one in the trail position, as in, hooked up to the rest of the train. The weight of the train will slow it down, while the slower lead loco will now be the faster of the two, and it's pulling power should alleviate the drag on the 2nd loco. You may see slack action between the two locos, especially if your trackwork isn't totally level, but it's believed in this setup, both locos will share the load.

Kennedy
 

jbaakko

Diesel Detail Freak
I know for sure that P2K E's are available in Powered/dummy configs.

The questions really all have been answered, so I'll step back.
 




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