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Unit A & B Consist

Started by Grizzly9, February 20, 2015, 06:04:24 PM

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Grizzly9

Hey Fellas - I run a PowerCab. I think I know the answer to this question but to avoid any problems, I am wondering; The When running an A and B unit together with DCC, is use of the consist required? If do I do this? " - Both A&B units are Bachmann F7 models

Len

It doesn't really matter what DCC control system you're using, there are two basic options for running an A-B set together.

If you plan to always run them together, you could just program them to the same address so they always respond to commands together.

If you plan to occasionally run the A unit by itself, and either leave the B in the shop or paired with another loco, then assign seperate addresses to the A and B and consist them.

Either way, the real question is, are the A & B units fairly well speed matched? This can be affected by the A and B units being from different manufacturers, or different product levels from the same manufacturer. E.g., Spectrum A and Standard Line B. The quickest way to find out is set them to the same address and put them on the track seperated by some distance. Start them running, and see if one runs away, or catches the other, real quickly. Or do they stay roughly the same distance apart for some time?

If the seperate or catch up real fast, you'll probably have to play with the speed tables to get them matched up before running them together. Whether as a consist, or just set to the same address.

Len
If at first you don't succeed, throw it in the spare parts box.

rogertra

Len.

Too bad this post can't be transferred to the DCC Board.  ;)

Cheers

Roger T.


Len

Quote from: rogertra on February 20, 2015, 06:31:36 PM
Len.

Too bad this post can't be transferred to the DCC Board.  ;)

Cheers

Roger T.

Yep!  ;D

This is exactly the kind of question I was thinking about, that keeps coming up over and over again, that should be in a DCC specific forum.
If at first you don't succeed, throw it in the spare parts box.

Hunt

You can set both locomotives to the same address. BUT DON'T!!

Speed match the locomotives if necessary.

I strongly recommend each locomotive have its own address and use the capability of your DCC system to set up a consist   -- use  Advanced Consist not the Old Style Consists. Follow instructions starting on page 25, Power Cab manual.

Grizzly9

Will do. - Thanks for the advice guys

rogertra

Quote from: Hunt on February 20, 2015, 06:47:42 PM
You can set both locomotives to the same address. BUT DON'T!!

Speed match the locomotives if necessary.

I strongly recommend each locomotive have its own address and use the capability of your DCC system to set up a consist   -- use  Advanced Consist not the Old Style Consists. Follow instructions starting on page 25, Power Cab manual.

While I agree that setting up an individual address, or even just using the default address for the 'B' unit while speed matching is a good idea, once you have the speeds matched I really don't see any advantage to not using the 'A' unit's address for both the 'A' and the 'B' unit.  After all, on the prototype, both the 'A' and the 'B' unit are considered one locomotive and all instructions would be given to the engineer in the lead unit.  What are the odds that the typical modeller will break up an 'A'+'B' unit consist anyway?

Now, for an 'A' + 'A' unit consist then yes, I can see the advantage of separate address when forming a consist. You can then call up either road number to be the lead unit on a train.  I have currently, for example,  F7A 209 + FB-2 192 and GP9 302 in a consist and either 209 or 302 can lead just by calling up its road number.   FB-2 192 is assigned F7A 209's road number as that consist has never, in the past five years or so, ever been broken up.  In fact, the whole consist has never been broken up in the past five years as it powers a westbound early morning through freight in the morning and returns almost last thing in at night with the eastbound through freight equivilant.

Cheers

Roger T.


Hunt

I don't use the one locomotive chasing another locomotive (master & slaves) method to speed match. Instead I match speed step to scale mph. This method allows me to consist any locomotive with any other locomotives.

rogertra

Quote from: Hunt on February 21, 2015, 12:39:17 AM
I don't use the one locomotive chasing another locomotive (master & slaves) method to speed match. Instead I match speed step to scale mph. This method allows me to consist any locomotive with any other locomotives.

Actually, that's what I really do as it's fairly straight with JMRI.

Cheers

Roger T.


Len

Minor point:

I wasn't recommending either method as being better, or worse, than the other. Just pointing out there are two ways to "skin the cat", so to speak.

As Roger says, "as delivered", many A-B units were drawbarred together and always operated as a pair. To gain flexibility railroads started removing the drawbars between the A-B pairs and installing couplers instead. This allowed them to run odd numbers of units together, such as A-B-A, A-B-B, A-B-B-B-A, etc., as needed. In order to replicate this, seperate addresses for the A & B are needed so the "hostler" can park the excess B unit somewhere, without the A unit following, when not needed.

If the drawbar will be left in, and I know folks who actually retrofit with drawbars, then using one address for both units will work.

Len
If at first you don't succeed, throw it in the spare parts box.

Ken G Price

Quote from: Len on February 21, 2015, 10:02:14 AM
Minor point:

I wasn't recommending either method as being better, or worse, than the other. Just pointing out there are two ways to "skin the cat", so to speak.


Len

My cats are very offended after I read them your post.  :o

I always run 2 engines together rear to rear. So both have the largest engine number. The lowest engine umber is set so it is going in reverse, when the main engine goes forward. It make things so much easier. Just like the class I's and regionals do.
Ken G Price N-Scale out west. 1995-1996 or so! UP, SP, MoPac.
Pictures Of My Layout, http://s567.photobucket.com/albums/ss115/kengprice/

rogertra

Quote from: Ken G Price on February 21, 2015, 09:34:31 PM

My cats are very offended after I read them your post.  :o

I always run 2 engines together rear to rear. So both have the largest engine number. The lowest engine umber is set so it is going in reverse, when the main engine goes forward. It make things so much easier. Just like the class I's and regionals do.


Ken.

I get the cat joke, ver PC.  :)

However, I do not understand the reasoning behind your number thing.

If you have the two locos in a consist and maintain each loco's address within the consist, i.e. each keeps it's own number and you don't assign the same engine number to them both, then surely it doesn't matter which loco leads, the high or the low number?  If the low number (No. 230) is facing east and No. 230 is leading an eastward train, then surely you simply call up loco No. 230 and that leads the consist.

OTOH, if the train is heading westbound then the loco facing west is No. 231 and it is therefore leading so you'd simple call up No. 231 and that loco would lead the consist?

That's how I do it?  Although NCE allocates a consist number, I never make note of it as it's just an electronic booking number if you will.  The only locos I ever refer to when calling a consist is what will become the lead loco's number.

Or have I missed something?

Cheers

Roger T.


Ken G Price

Roger. I do it the way I do so I do not have to even bother with consisting.
There is no reason to change out engines. The yard engines, two MP-15's, #1531 and #1530 both are given 1531 as the programed engine number, with 1530's CV29 set so as to run to the rear when 1531 goes forward. The two GP38-2's that are the local is set the same with the highest cab number being used. Same with the sets of road engines going to and from staging.

The two SD40'S have the same engine number, as that was the only number available. So having them always running together works just fine. I just need to look a the headlight to see which one is the lead.
Doing it this way is simple and easy for me. As I have no reason to form and break up a consist.
Ken G Price N-Scale out west. 1995-1996 or so! UP, SP, MoPac.
Pictures Of My Layout, http://s567.photobucket.com/albums/ss115/kengprice/

rogertra

Quote from: Ken G Price on February 22, 2015, 12:56:48 PM
Roger. I do it the way I do so I do not have to even bother with consisting.
There is no reason to change out engines. The yard engines, two MP-15's, #1531 and #1530 both are given 1531 as the programed engine number, with 1530's CV29 set so as to run to the rear when 1531 goes forward. The two GP38-2's that are the local is set the same with the highest cab number being used. Same with the sets of road engines going to and from staging.

The two SD40'S have the same engine number, as that was the only number available. So having them always running together works just fine. I just need to look a the headlight to see which one is the lead.
Doing it this way is simple and easy for me. As I have no reason to form and break up a consist.

Ken.

Now I see.  We have two ways of approaching the same issue, how to run two (or more) locos in "consist", just to use the word.  I consist them to maintain road numbers and you just assign them both the same engine number like I do when I consist 'A' and 'B' units together.

The reason I maintain road numbers when in consist is the roundhouse hostler never knows which unit will lead next time the consist is required for a train.

However, I must disclose a little secret.  I have two consists that include dummy Athearn Blue Box GER F7A units.  These two consists have powered CNR 'A' units in the consist so the GER units are placed in the lead.  These two consist are used on an overnight CNR/GER pool freight to the Maritimes.  Therefore, the GER 'A' units are always in the lead, both east and westbound.  What I've done in this case is assign the GER 'A' unit's number to the powered CNR trailing 'A' unit so when addressing the train's locomotive the operator uses the lead unit's number, which happens to be the GER dummy 'A' unit. 

Why use dummy units?  They have had various details added and have been weathered etc. and I really don't need the expense of purchasing two more sound equipped F7A units and go through the painting and detailing all over again.  On the old GER they used to be trailing units so that wasn't an issue.  All I've done since DCC days is to add wipers to all the wheels to provide power to a lamp in the headlight so they look good leading.  :)

I'm cheap.

Cheers

Roger T.


Ken G Price

#14
Roger, I won't tell any one here about your secret. ;D

Having only 12 engines make it easy the way I do it. I can see that having more makes sense also. As well as I'm sure you just enjoy consisting different engines together. :D
Ken G Price N-Scale out west. 1995-1996 or so! UP, SP, MoPac.
Pictures Of My Layout, http://s567.photobucket.com/albums/ss115/kengprice/