More Speed Tables


In my previous attempts at speed matching I had set them up as CV19 consists for matching since Digitrax decoders change BEMF settings in consist mode. With BEMF off I noticed some of my locomotives were not very smooth at lower operating speeds so I decided to take a stab at leaving BEMF on and consisting using the functionality built into the Digitrax command station (I believe it’s called Universal consisting). Using this approach lets me have BEMF and makes it easier to build up and break down consists while operating.

This meant that I had to reconfigure the speed tables with BEMF on. As I’ve mentioned earlier my method for building speed tables is to take assign a target scale speed for each of the 28 speed steps. Then I use my Bachrus Speedometer to find a value for each of the 28 speed step that is as close to the target speed as possible.
(Example table)

Speed Step Scale Speed Loco 1 Loco 2
1 2 15 18
2 4 20 23
3 6 25 28
28 56 100 105

The Bachrus speedometer is intended to be used with their roller sets, however due to their higher cost I only have the speedometer so I prop the locomotive up like this (with alligator clips connecting it to track power).

After I’ve got it all setup and rolling on the speed0 properly I keep up the locomotive on and set the speed to 100%. I find this is easier than trying to make sure it’s in a specific step. I fire up JMRI and make the speed table a flat line at my starting speed and as I get the value for a step I move to the next one till I’ve built a full curve.

In this screen shot (speed table programmer in Ops mode on left, speedo output on right) I’m working on Step 11 which I have defined as 12 scale mph, based on the Speedo reading I’m as close as I’m going to get. Generally I get as close to the MPH as I can (I don’t try to match increments smaller than 1 mph). This does leave a bit of push in pull between the locomotives but it would be possible to get that precise and that’s what happens on the prototype anyway. I run all metal Kadee couplers on my locomotives so they seem to stand up to the push and pull of operation (at least so far).


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