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hopefully someone can help with this. I very recently got two 121's, over the moon with them. I first ran them DC for a run in all good, with both on the same track, one was quicker than the other.

I installed the decoders (lok non -sound), got them running DCC, all good. I then set up a double header (or consist, im using a Hornby Elite). One still runs quicker than the other. 

I presume there is an adjustment to a CV required, im not well aquanted with adjusting CV's, any help would be much appriciated. 

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4 hours ago, Alan564017 said:

hopefully someone can help with this. I very recently got two 121's, over the moon with them. I first ran them DC for a run in all good, with both on the same track, one was quicker than the other.

I installed the decoders (lok non -sound), got them running DCC, all good. I then set up a double header (or consist, im using a Hornby Elite). One still runs quicker than the other. 

I presume there is an adjustment to a CV required, im not well aquanted with adjusting CV's, any help would be much appriciated. 

It's a process the DCC gurus call "Speed Matching". There are many good articles and videos on the subject if you Google search the term. American modellers have great experience with this as they often run several locos in a consist.

Basically the process involves adjusting 3 CVs.

CV2 which controls the speed of the loco at speed step 1 on the throttle.

CV5 which controls the speed of the loco at max throttle speed.

CV6 which controls the loco's speed at the middle speed step.

Bear in mind that some cheaper decoders will not allow adjustment of these CV's.

Hopefully you have a large loop on your layout as this makes the process much easier. Set the 2 locos up a couple of inches apart and run them both at speed step 1. Adjust CV2 so they are at the same speed. Then do the same with CV5 while the models are running at top speed. Once you have those set work on CV6, it's much easier when you have CV's 2 and 5 matched. You probably won't get them running identically but just try to get them as close as possible. Also try to adjust the CV's on only one loco, adjusting it to match the other one rather than fiddling with CV's on both locos at once. That can get very confusing!

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I had that question when putting my consist together.  When I was running in the two locos I realised that 125 needed to be at speed step 62/63 on an NCE PowerCab to keep up with the 131 running at speed step 60.  I take it that at reduced speed steep 31 on 125, then 30 would be corresponding on 131.  That's hardly worth worrying about and half a drop of oil might sort that, but it's too early to go there.  Using NCE the advise is to put the faster loco first and I've done that.  So, I set up the consist as per the NCE manual and all works fine (I didn't need to change the directional CV bit as the NCE system asks if the loco is running forward or reverse and sets up the consist accordingly.  I have a video record of them running in a consist at speed notch 50 and slowing to stop and the running is nice and smooth.  You can view that at  https://youtu.be/KXydwaGbzes

Hope that helps.

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8 hours ago, irishthump said:

Yes, but not a lot of help to the original poster as he isn’t using a Z21.

Ok but as I said 'curious' how some DCC systems can aid speed matching. Interesting piece below, perhaps more relevant to US consisting as they ofter have more than two locos, often 3 or 4 whereas in the part of the world just a pair as with the 121s. Back to steam days up to 3 stream locos banked heavy trains up the hill out of Cork until the 800s.

https://dccwiki.com/MU_consisting/Speed_Matching

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The difference in speed between Alan's 121  may become less noticeable as the locos are run in and it may be a better option to operate on DC or leave the decoders at their default setting.

I found that it was more trouble than it was worth attempting to speed match consists of locos with different speed characteristics on an American layout, and ended up only consisting locos with the same characteristics usually with the decoder at its default setting.

I generally ran 3-5 loco consists, but ended up keeping Atlas, Bachmann and Kato locos in separate consists in order to reliably operate 20-30 car freights.

Funnily enough speed matching was less of an issue when I operated the layout on DC the main limitation was the 1 AMP rating of the H&M transformer.

 

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1 hour ago, Mayner said:

The difference in speed between Alan's 121  may become less noticeable as the locos are run in and it may be a better option to operate on DC or leave the decoders at their default setting.

I found that it was more trouble than it was worth attempting to speed match consists of locos with different speed characteristics on an American layout, and ended up only consisting locos with the same characteristics usually with the decoder at its default setting.

I generally ran 3-5 loco consists, but ended up keeping Atlas, Bachmann and Kato locos in separate consists in order to reliably operate 20-30 car freights.

Funnily enough speed matching was less of an issue when I operated the layout on DC the main limitation was the 1 AMP rating of the H&M transformer.

Agree, two 121s once run in with the same decoder settings should more or less match up which has been my experience with 121s and consisting 141 pairs. Same chassis/motor and same decoder makes a huge difference. Also found TLCs a PITA if speeds slightly mismatched compare to knuckle couplings as when one loco is pushing the other the TLCs tend to slip and one rides over the other leading to a derailment on the next bend or paintwork. 

Clip below of three different steam locos (DCC converted wired decoders) with different decoders pulling and pushing a little but they could run together without derailing or much wheel slip. 

 

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18 hours ago, irishthump said:

It's a process the DCC gurus call "Speed Matching". There are many good articles and videos on the subject if you Google search the term. American modellers have great experience with this as they often run several locos in a consist.

Basically the process involves adjusting 3 CVs.

CV2 which controls the speed of the loco at speed step 1 on the throttle.

CV5 which controls the speed of the loco at max throttle speed.

CV6 which controls the loco's speed at the middle speed step.

Bear in mind that some cheaper decoders will not allow adjustment of these CV's.

Hopefully you have a large loop on your layout as this makes the process much easier. Set the 2 locos up a couple of inches apart and run them both at speed step 1. Adjust CV2 so they are at the same speed. Then do the same with CV5 while the models are running at top speed. Once you have those set work on CV6, it's much easier when you have CV's 2 and 5 matched. You probably won't get them running identically but just try to get them as close as possible. Also try to adjust the CV's on only one loco, adjusting it to match the other one rather than fiddling with CV's on both locos at once. That can get very confusing!

irishthump, many thanks for the reply. Leaving one loco as is and the changing the other makes sense. I'm using a Hornby Elite, i've never tried to alter any CV's so im a little hesitant. The decoders are the lok-pilot (got them with the locos), so I presume the CV numbers you mentioned above still apply. 

If anybody knows or has advice on how to read/write CV's using a Hornby Elite, it would be much appreciated. 

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Alan, I did have a look at the CVs that needed changing for speed matching but the factory defaults are the same for both locos and as their speed difference was so small I left things at the defaults.  I also thought that a little running while in a consist formation would also help the running in process.  Setting CVs is nothing to be intimidated by and will soon become part of your DCC toolkit.  Does the Hornby Elite come with a manual?  That should explain how to set CVs in the first place and it should also explain how to set a consist.  I'm sure there must be some YouTube videos that also show you how.  

 

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3 hours ago, Alan564017 said:

irishthump, many thanks for the reply. Leaving one loco as is and the changing the other makes sense. I'm using a Hornby Elite, i've never tried to alter any CV's so im a little hesitant. The decoders are the lok-pilot (got them with the locos), so I presume the CV numbers you mentioned above still apply. 

If anybody knows or has advice on how to read/write CV's using a Hornby Elite, it would be much appreciated. 

If both decoders are LOkpilot you can use the Auto-Tune feature which may well improve things.

Just place the loco on a straight piece of track then programme CV54 to a value of 0. Then press F1 and the loco will take off like a rocket for a few seconds. (Make sure nothing is in the way!)

This reads feedback from the motor and stores it in the decoder. Do it with both locos and see how they run after that.

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thanks for all the replies and advice. Im going to take the easy option and 'let them run in for a while', any thoughts on how long this should take?

my layout is temporary and unfortunately it has to be dismantled to get at the attic storage where the xmas decorations are!!! so it maybe a while before I get back to this. Some of the above questions will probably be asked again :) 

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