Speed Matching

[Eric97123]

This is great info http://www.ncmrc.org/howto/Speed_Matching_DCC.pdf

[Medina1128]

Without using DCC, you can closely speed match locomotives of the same model from the same manufacturer. I run mu lashups using sets of Athearn R-T-R GP38-2s and others made from Athearn Genesis F-units (A-B-B-A). The lead A-unit and the B-units are all powered, while the trailing A-unit is a dummy. I also have some Blueline units that, using the DCMaster, are programmed as a consist by programming their starting voltage and the sound start and shut down voltage the same. Also, you can program them as lead and secondary units (lights, sound (horn/bell), etc.). Just make sure your control units have enough power. I'm using MRC Tech 4 controls. Another lashup is made using Proto 2000 GP38-2s, while yet another is made using a couple Bachmann Spectrum Heavy Mountain 4-8-2s.

[misterconsister]

I am no expert, having only been in this a little over two years, but this is what I've discovered and a few of my preferences.

There are many schools of thought on what's necessary to speed match locomotives and, like all things in this hobby, you have some choices.   Some preferences you may know right-off, others will develop with time and experience and how you end up operating locomotives on your layout.  For me, big diesel consists with helpers, like those run in the Sierras and the Rockies in the 70's drove me to want to have very closely matched locos.  

Here a list of things that you might want to consider:

• Speed matching is done best with decoder-controlled locos and therefore DCC.

 

• For closely-matching locos reliably, embrace the fact that you will have to learn about CVs, speed curves and steps.  It's a little over-whelming at first but it provides incredible variation for controlling locomotive speed, response, lights and sounds.

 

• Speed tables are basically made up of decoder values (range 0-255) at "steps" that correspond to each "click" of the throttle.

 

• Use a throttle that has "clicks" and a readout for doing speed-matching.

 

• I have a Zephyr with the rotary big-dial throttle lever but I use my DT400 throttle to do the controlling when speed matching because I can see which "click" I'm on when running a loco.

 

• The DT400 displays %total voltage from the command station at each click.   There's 100 individual % values displayed (0-99) with a full cranking of the knob (2-3 times around).  I think its called logic-controlled versus rotary, or something like that.  I have no experience with any other throttles but I think the NCE might display in steps.

 

• You can have either 14 or 28 steps in your speed table.  For each loco, you have to choose whether you use 14 or 28 steps.   Use CV29 to toggle it.  This data is stored in the decoder in the locomotive.  There's another CV related to 14-28 tables but I don't have it in front of me here.

 

• Learn about CV29 - it's a doozy.

 

• For the 28 step choice, you can allow your throttle to interpret the curve between the adjacent 28 steps with a few more values between each making the curve smoother and therefore making your loco run smoother.  This interpretation has 128 possible pts along the curve whereas 28 step operation (without the throttle interpretation) is with a 28 pt curve.  Older decoders, or most of them, didn't allow for this I believe. 

 

• For the DT400, there is a thing called "status" editing (took me too long to figure this out!).  With it, you can tell the command station whether or not to use 14, 28 or 128 step curves with a given loco.  I selected 128 to get all the single % pt read-outs (0-99) as I turn the throttle knob.

 

• How do you map 100 individual % values into 128 steps?  You'll see on the DT400 that every 3-4 clicks the % value doesn't move, that's how it compenstes for the discrepency. 

 

• To speed match, you're going to want to select a candidate loco and  measure and record its performance.   For that loco, you're going to want to establish preferred speeds at a given throttle value and make all locos do the same.   To do that, you'll need to adjust the voltage individually for each locomotive by varying the 0-225 value at each step according to your speed table.

 

• There are a lot of CVs to program (again and again) if you're using a 28 step speed table.

 

• Do yourself a favor and get an old computer or a laptop and get DecoderPro installed to help you set and store all the decoder's CV values.   DecoderPro is a free Java-based program that is very comprehensive for operating many of the electronic aspects of a model railroad.   The loco decoder section is just a portion of it.  It was created and is improved constantly by a large number of contributors.  There are others too but I will just talk about DecoderPro since that's all I've experienced.

 

• The most handy thing for me is using the sliders on the speed table values to fine-tune how your loco responds to clicks and voltage.  The latest version has even better ways to move the sliders in groups for smooth curves.

 

• You can use Service mode or Operations mode to set CVs.   However, you can mess up a lot of loocs at once with Ops mode if you don't know exactly what you're doing.  I suggest Service mode until you're more familiar with it all.

 

• In DecoderPro you can also store all your information regarding your locos and rolling stock in nicely-formatted interfaces. 

 

• To communicate between you computer running DecoderPro and your command station you need a connection that usually involves a cable and some circuitry to translate between them.  I use Loco Buffer USB that has a jack that plugs into my LocoNet on my Digitrax Command station and a USB connector for a port on my laptop.  I can't remember but I think this was about $40 or so.

 

• Install a programming track section on your layout that is easy to access.  It must be isolated electrically from the rest of the layout with insulated joiners or breaks.  You can toggle it between track power and programming mode "power" with a simple toggle switch.

 

• Select the slowest loco (of a group of locos likely to consisted - or MU'd) as your baseline loco candidate.   Use its speed curve or, more likely, adjust it to suit using the speed table.  Some have suggested that you decrease its top speed so that if you get a slower loco later, you can accomodate it.  

 

• Measure the speed of the loco at as many of the 28 steps you'd like (minimum of 3: start, mid, max).   Record which step or %voltage happened at a given speed.  The matched locos need to be going at that speed at that same % voltage value on your throttle readout.   Setting the CV values, for a given step, to a value between 0-255 will allow you to do that.

 

• Make sure your engines are "warm" and are not too new.  Some have said a couple of hours running time from when brand new is a good practice.

 

• Figure out how you want to measure speed.  So far it seems to be timing the loco over a given distance or having a speedometer car attached to read out speed.

 

• For the former, you can measure a stretch of track and time the loco as it traverses and do the calculation to what its speed is (there are tables or you can make your own).   Of course the scale you're operating in matters for this.

 

• There are also "speed tunnels" that you can set temporarily on the track and it will measure the speed ad display it, or, you can get a set of sensors and a display device that will do the same but less obtrusively.   Trainspeed makes some like this.   Sensors are fairly small and can be disguised somewhat and can be visible light detectors (optical) or infrared (IR).  I think Trainspeed makes the ones in both optical and IR but I can't seem to locate the IR versions right now even though I've tried.  Anyone know where I can find them?

 

• Or you can use a "speed wagon" or a railcar towed behind the loco with an LED display that shows real-time speed.   Not sure where to get speed wagons - anyone?   Some folks have crafted thier own but it takes some MR-fortitude from what I can tell.  I'm hoping locos someday will be equiped somehow to register and transmit its speed - just like the prototypes! 

 

• If you don't use a speed table you can set just a few critical CVs that will approximately match your locomotives.  These CVs are CV02 (start), CV05 (max) and CV06 (mid) (don't ask me why CVs 5 and 6 are juxtaposed that way).

 

• I've only got some roughly matched locos right now as I've just started matching them but I have been doing lots of homework.  RIght now I've got 5 of my big D&RGW diesels (SD-50s, SD-40T-2s) pulling "long" N-scale frieghts (~35 cars - because that's all I have!). 

 

• You can speed match helpers but some say it's "more" prototypical to operate them with separate operators.   I think I'll match mine closely and run them from my DT400 with its 2 throttle knobs as I'm a one-man show anyway.

 

• I'm new at this and could be misunderstanding some things so hopefully others will chime in.

 

 

[wyldmanr8cer]

Can anyone tell me the best way to speed match locomotives? What do I need as far as equipment to accomplish this task? Thanks for everyones help!!!