I need some clarification on speed matching. I have two Athearn P42s each with a TCS T4X decoder installed in them. The decoders are great and do a great job on ditch light effects with LEDs.
Anyway my questions are: Do the couplers have slack in between the two units or should be tawt (spelling)? Do I need to start by loading the appropriate CVs from the speed table literature and work from there?
EDIT: Forgot to mention the system is an NCE Power Cab
Thanks in advance.
Will
Here is how I did mine. If your decoder has EMF feed back turn it off.
1 Warm up both engines for 5 minutes.
2 Take the slowest starting engine and use CV 2 till it starts at the same time as the other.
3 I set CV 5 to 256, that is top speed on both engines
4 I then set CV 6 to 128 this is mid range and where most of are engines will spend most of there time.
5 I then played with CV 5 on the faster engine to match it to the slower engine.
If you cannot get them perfect, make the faster engine the led engine.
Has worked for me.
Cuda Ken
I hate Rust
The easiest way to speed match is if you have a continuous run layout. This is also where the "ops mode" or programming on the main capability of your DCC system comes in handy. Put both locos on the track, a foot or two apart. Consist them and start them moving. Start with V-start, V-mid, and V-max (CV2, CV6, and CV5 in that order) and see if you can't get the to run well together. Whilwe the consist is running you can address either one and use Ops Mode programming to adjust the CV values. If you can;t get a decent match that way you may have to go to a full speed table - at that point it's very helpful if you have a computer interface and can use DecoderPro.
It's a time consumign and slightly tedious process, there's no 'magic button' you can push and just match speeds It's a lot of trial and error until you get just teh right values. They just need to be close - so the faster one doesn't continuously push the slower one, or the slower one doesn't hold back the faster If you start them a foot apart adn they are matched, by the tiem they get back to the starting point they should still be a foot apart but if they changes by a fraction either way it won't hurt. If they end up coupled, or 2 feet apart, they need adjusting.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
cudaken 3 I set CV 5 to 256, that is top speed on both engines Cuda Ken
I slight correction, the maximum value a byte can hold is 255 not 256. I agree with all your others points.
Jack W.
I usually start by getting the running speeds the same at say 1/2 full throttle, then go back and use CV 2,3 and 4 (starting value, starting momentum, stopping momentum) to get the two engines to start and stop together.
You don't really need to do speed curves in my experience, unless you're using a decoder that doesn't support CV 5 and 6 like some sound decoders do.
Also, you may want to not have either engines have a full 255 as the top speed, since later you might want to speed match them to another locomotive whose speed is slower than these two engines. I would maybe start with CV5 at 200 and CV6 at 100 and go from there.
Jack, I stand corrected on CV 5, it is 255 not 256.
I, too am having some difficulty speed matching loco's. I have a Digitrax Super Chief system...radio controlled. My understanding of what to do is weak. I THINK I understand about CV2 & CV5 programming (my decoders don't support CV6 according to the QSI ref. Manual) but what about CV66 & CV95 (Forward and Reverse trim). I have matched the speed on a large (over 100ft.) circle of track, but when I run the engines they sometimes come uncoupled on a curve. They stay close together (within an inch or two) then recouple after several feet of running. The engines are both Walthers RS-27 's. You would think that both engines being identical that they would already be matched. My first experience with matching engines was with BLI E-7 's...they matched perfectly out of the box. I put them in a consist and hooked them to a passenger train and away they went...no problem. I have been trying to solve this problem by myself for 10 days and many hours of "study". Any advice from anyone would be greatly appreciated.
Thank you all for the responses. I will try to figure it out this week when I am going to be off work.