Model Railroading > Speed Matching Question

Using my NCE PowerCab, I have begun to try to match the speeds of a few of my Atlas Master Series locomotives, all GP 38's.  My goal is to have them run steadily at pretty slow speeds at the same speed setting as each other, as the layout depicts mostly urban industrial switching.  I have been making adjustments using CV2 to try to do this, and actually having some success.  I don't have the JMRI program, but have been matching the speeds by eye on a straight section of track. And I've been using one locomotive as the "standard' to which I am trying to match the others.

But I have two questions...

First, is there any advantage to me setting this up in 128 step mode versus 28 step?
Second, which, if any, other CVs would be helpful in speed matching?

Thanks for any help.  And just for interest's sake, here's a photo of two of the GP38's sitting outside the JSSX maintenance building.

Jim
https://jssxrailway.blogspot.com
 

---

128 step will always give you finer speed control because you're making much smaller adjustments with each step.

I would recommend 128 speed step control, especially if you are mainly working a slow-speed switching layout. essentially you get 5x more control out of each speed step.

I speed match my locos similar to you: I have one "Standard" unit I use for matching everything else to.

In addition to CV2, you need to be concerned with CV6 and CV5.
CV-2 only controls your starting voltage (aka, the speed at speed step 1)
CV-6 controls your mid voltage (speed at speed step 14 [in 28-step control] or speed step 64 [128 step control])
CV-5 controls the max voltage at the highest speed step

If you are mainly doing slow speed running, you may be able to ignore CV-5.

One additional note is to warm up your locomotives before speed matching them. I've noticed (especially with Athearns) that if I don't run them around the layout for 5 to 10 minutes before speed matching, they end up fighting each other once they warm up.
   -Caleb

You mentioned Atlas Master decoders.  I have a lot of trouble speed matching Atlas Master engines from the mid 2000s.  I'm not sure if CV3 and CV4 work as advertised on all of the Atlas decoders from that era. I'm about to do some more decoder matching with the locomotives I have from that era, so I'll know for sure shortly.

The problem you will have with the old Atlas decoders they only use CV2, to speed match you will need to use speed tables.  That is why I recommend that you use 28 speed step mode and once matched switch to 128.  I would also use JMRI to help with the speed matching and their speed tables list all 28 speed steps. 

Santi