Speed-Matching

[davefoxx]

I just purchased an Accutrack II Speedometer.  I've read the instructions and even found a few videos online about how to use it to speed-match locomotives.  Now, I have to figure out what settings to use for my locomotives.

Should I set up the fleet to try to emulate the prototype?  For example, should I program a U23B to a maximum speed of 70 mph?  Honestly, I really don't like the idea of having to crank the throttle up 128 steps to reach max speed.  But, that could be controlled by setting the maximum speed at, say, half throttle, so anything above 64 steps wouldn't increase the speed.

Or, should I do the more logical option and set all of my locomotives the same, with, for example, a maximum speed of 100 smph, so that each speed step will approximate one smph.  Again, I don't crank the throttle, so a maximum speed being in excess of the prototype is not really an issue.  But, that will provide the convenience of setting the throttle at 30 and knowing that is approximately 30 smph.  I can tweak the speed curve to achieve this for each locomotive.  Then, throttle at 10 would be 10 smph, throttle at 20 would be 20 smph, throttle at 30 would be 30 smph, etc.

Thoughts?
DFF

[Scottl]

I wonder if scale speed matters on the small layouts most of us operate.   I run the trains at a speed that "seems" right, rather than any notion of what speed it actually is.  The speedometer could help you match to whatever speed you want.

I'm interested that you use 128 step speed.  That seems like a lot of steps- why this over 28?

[Bendtracker1]

Dave,
I friend showed me how to do this a long time ago.
The first thing he told me was to use the full speed table.
Pick a setting you like, one that makes the locos run the way you like.
Then use the same setting for all your locos.

This is what I chose for my speed table, it's called a Log Curve:



I use Digitrax, so this is my throttle settings;
99% = 70 smph
49% = 58 smph
25% = 40 smph
12% = 22 smph

These speeds are close to what I get when I use the "Log Curve" setting.
Once I start speed matching I start tweaking the Forward and Reverse trims to speed up or slow down each loco until they register the above speed at each throttle setting.
Adjusting the trims will not change the set speed table.

This give the most response to speed in the first third of the throttle.
Most of the time I we run our trains around 15%-25% throttle during our sessions.

You can read up on how I go about it on my blog.

http://thelittlerockline.blogspot.com/2012/04/speed-matching-locomotives.html

 

[jagged ben]

Should I set up the fleet to try to emulate the prototype?  For example, should I program a U23B to a maximum speed of 70 mph?  Honestly, I really don't like the idea of having to crank the throttle up 128 steps to reach max speed.  But, that could be controlled by setting the maximum speed at, say, half throttle, so anything above 64 steps wouldn't increase the speed.

If your prototypes have different top speeds then they won't be matched if you run them together.  So no, this approach, if implemented simply, doesn't make much sense.

Or, should I do the more logical option and set all of my locomotives the same, with, for example, a maximum speed of 100 smph, so that each speed step will approximate one smph.  Again, I don't crank the throttle, so a maximum speed being in excess of the prototype is not really an issue.  But, that will provide the convenience of setting the throttle at 30 and knowing that is approximately 30 smph.  I can tweak the speed curve to achieve this for each locomotive.  Then, throttle at 10 would be 10 smph, throttle at 20 would be 20 smph, throttle at 30 would be 30 smph, etc.

That's probably what I'd go for.  Extensive speed matching isn't something I've gotten around to yet.  That will have to wait until I can have a permanent setup and let a script do it.

If it takes too long to crank the throttle to 70 speed steps, maybe just do a simple 1/2 ratio.  i.e. 35 on the throttle would be 70mph.

[peteski]

Should I set up the fleet to try to emulate the prototype?  For example, should I program a U23B to a maximum speed of 70 mph?  Honestly, I really don't like the idea of having to crank the throttle up 128 steps to reach max speed.  But, that could be controlled by setting the maximum speed at, say, half throttle, so anything above 64 steps wouldn't increase the speed.

Or, should I do the more logical option and set all of my locomotives the same, with, for example, a maximum speed of 100 smph, so that each speed step will approximate one smph.  Again, I don't crank the throttle, so a maximum speed being in excess of the prototype is not really an issue.

I think that you missing the point Dave.  You say that you don't crank the throttle.  But the whole point of limiting the top speed is to give you better range (and finer speed control) on your throttle.  That way you aren't restricting yourself to only using part of your throttle knob's angle.

But then in DCC many throttles don't have a "real" speed control knob.  That is a shame IMO.  I don't much care for those endlessly spinning encoders or up/down buttons.  The feel and control is not the same. But I would still set up the maximum speed on your locos to something realistic. If it takes too many presses of a button or spins of the encoder to get to the 128th step then just run your locos in in 28 step mode.   But maybe I'm wrong. Limiting the top speed and using full 28 speed steps is probably not different than leaving the decoder's top speed unmodified (high) and then just using lower portion of the throttle's 128 step range.

[AKNscale]

Depends on what you want. All of my DCC locos are limited to 50 SMPH and speed matched using the start, mid, and high method. I did this so all can run together. Usually during the annual Fur Rondy show we have here in Anchorage I run 10 GP's together to demonstrate what you can do with DCC. When I get started on "The big layout" all of my motive power will be speed matched to be able to run together for ease of use.

[davefoxx]

Thanks for everyone's input!  I think what I will try to do first is stick with 128 steps, which gives finer control than 28 steps.  I'll probably choose an arbitrary number like 100 smph for maximum speed, which will allow me to set the throttle at 10 for 10 smph or 50 for 50 smph.  I will then be able to control the locomotive with only about 25-50% (i.e., the lower portion) of the throttle under most circumstances.  Again, finer control with smaller speed steps, but I don't have to crank it up to 128 to go 50 smph.

Thanks again,
DFF