Speedometer
Speed Matching
Consisting Engines of Different Manufacturers Using DCC/DecoderPro
(Provided by Keith Keith Albright of the Four County Society of Model Engineers)
In most cases, DCC has made it easy to consist engines that could not be run together in
analog mode. The following are tips and procedures that I use to allow engines to run
together. I make it a habit of setting up all of my freight engines to run at the same speed.
I do likewise with my passenger engines. If you use the same type of engine for both, you
might want to make them all the same speed.
What Speed? - Which engine do you select as your constant. Three possible choices are:
- The slowest engine (top Speed)
- Your Favorite engine
- A sound equipped engine
All three can be used and each has advantages and disadvantages. The slowest engine has the
advantage of guaranteeing that all other can be consisted. Specialized engines such as shays
are usually ignored. If you are partial to a certain manufacturer (ex Stewart), you may want
to make that your standard.
A word on engine motors and decoders. Engine motors can be divided into 2 categories; Open
frame and can motors. Open frame motors tend to be faster and more subject to speed variation
than Can motors. They draw more amperage than most can motors and are a little more difficult
to get going at low speed steps. Although cheaper, with a little care and maintenance, they
can give many hours of long service. They are commonly found on less expensive engines. Can
motors tend to be much smoother in operation throughout their speed range. They have low
current draw and little maintenance. They are found on newer and better quality engines.
If you plan on consisting open frame and can motor engines together, I would recommend
using TCS decoders for the open frame motors. Dither, a feature of TCS decoders, does a great
job of overcoming the slow speed hang up of open frame motors. I would also select a can
motored engine as your constant. Once you have decided on your constant engine, the following
steps should allow you to run engines at the same speed.
- If the engine is new, it should be run in for an hour or two before setting the
speed
- Warm up both engines and make sure their wheels are clean. 3-5 minutes usually
suffices. This will also give you an idea on how close the speeds are for the 2
engines.
- Make sure CV19 is set to 0 for both engines. Also, make sure your engine is not set for
alternate speed steps. If you want to increase the starting voltage on your engine, do it
before proceeding to step 4.
- Make sure the engine you want to match is in your decoder pro roster. Crank up decoder
pro and use programming on the main. Call up the engine you wish to speed match from your
roster.
- Make up a normal consist with your constant engine as the lead engine. Do not lash the
engines together. 8-10 inches between them is a good start.
- If you are using a decoder with BEMF, it should be turned off for consisting.
- Select the speed table screen for the engine called up in decoder pro.
- Select user defined speed table on the screen
- Set step 1 of your speed to the starting voltage from the top of the page. Set step 28
to 255
- Click on match ends on the speed table. Then write this to the loco.
- Run the locos. If you have made a good choice on your base engine, the following engine
will probably be faster. Reduce the speed step 28 setting; Match ends and write to the
engine. Some systems/decoders will allow you to do this on the fly, other will make you
stop the engines. Repeat this procedure until the engines speed match. After you do a few
you will be able to match an engine faster than you can read this procedure. We have found
that this method gives us great speed control and is actually faster to do than using the
Vmid and Vmax settings. It also eliminates fooling with forward and reverse trim if you
decoder requires it.
- If your decoder does not support 28 speed step settings you will need to use the method
outlined in the other clinic.
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