I have started setting a lot of my engines to a default like setting. Most, almost all, of my collection has digitrax decoders, and I am trying to use the default settings in the book for CV2, CV5, and CV6 for the respective locomotive type. I realize this won’t be exact, but the engines should be close… Except the Athearns. The RTR engines need a higher numbers to get them going and a good cruising speed, while the old Gensis needed CV2=1 and still starts to fast. I have about fifty engines, and I like to consist many different combinations. I realize that if I want engines to consist well together I have to speed match them. What recommendations are there for default settings among different manufactures?
Nile,
Every locomotive is different - even the same manufacturer and model - so you can’t rely on decoder defaults for consistent speed matching. Other factors that can affect it are lubrication and binding (steamers). If you haven’t cleaned and relubed your locomotives in a while, this may be a good time to do it.
Tom
You are on target with adjusting CVs 2, 5, 6 to get locos speed easily matched, creating a simple three point speed curve (either linear or dual sloped). That’s of course easier than setting all 16 or so speed table items. But it’s not about default settings, it’s a trial and error process. Some folks take a single loco and match their others to that one so any could be consisted with another. That really depends on whether you want them all to have the same top speed and be able to consist any with another. For example, I want my yard switcher to run slower at top speed than my passenger E units, and won’t be consisting them. Some folks set the speed curve by using a speedometer / timing approach.
I just run two locos near each other to get them matched. I typically consist the same type locos with their siblings (e.g., SDs, F units, etc) but have not (yet) made them all consistent with a common one or even several. I simply adjust CV2 for a nice speed step one smoothness, then set to speed step 128 and adjust CV5s (first adjusting one to get the top speed I want, then adjusting the other to match it) to get them running a constant distance apart, then set them to speed step 63 and adjust CV6 mid speed to get similar speeds. I usually set the speed step 63 speeds (via CV6) at less than half of top speed for finer control at lower speeds. I may then go back and adjust CV2 for the loco that’s slower at speed step one to run close to the faster one at that speed step. Note the locos do not need to match perfectly to run ok together.
When speed matching, I believe most guides suggest to turn off momemtum. When consisted, many different type decoders work together fine regarding BEMF and some may do better with it turned off so the locos don’t fight. When consisted I also recall that some decoders (e.g., LokSound) may have different momentum &
On some consist, turning off BEMF has helped with surging and pulling. But not all engines/consist responded well to the change. I also use the momentum setting in my NCE Power Pro throttle. But, my consist are permanant and each engine has the same address.
I don’t have any of these problems with engines and consist that are running with the RailPro system.
What it comes down to is that you have to match start speed with the one that starts fastest with the minimum setting in CV2. That’s as slow is it will ever start. At the top speed, you have to slow down the faster ones to matchg the slowest one.
You’ll never get exact matches with locos with vastly different motors and gearing. No system can fix this. Railpro and others do the same exact thing to match speeds.
–Randy
Yes, to consist engines well together you have to speed match them. I like to speed match to a practical scale speed like CV2 Start at 4 scale mph CV6 Mid is 38 scale mph and CV5 Max. is 64 scale mph.
I have tried to make an example of an FA and AB speed matched with two different decoders.
Silk_City_speed_slopes.pdf
I also like to use speed traps to measure my scale mph with a stopwatch. This is an example of a switcher to produce 4, 38 and 64 scale mph with CV57=0, 6 and 15 Digitrax decoder.
Example_Speed_Traps.pdf
Any suggestions on using my straight line slope idea?
Bob Frey
The initial results in the first chart look more than close enough to MY those locos without problems. I’ve never felt the need to go all the way to implementing 28 step speed tables to get locos to MU. We never had such capability with DC power and yet people ran 2-3 or more locos together with no issues. DCC is not different.
Some decoders do a better BEMF implementation than others - Digitrax’s, at least prior to the latest Series 6 decoders, which I have yet to try, was one of the worst and would cause bucking in consists (which may explain why the default decoder settings were such that BEMF was turned off when using CV19 consisting). TCS and ESU have superior implementations - I just put the locos on the track and couple them up, no speed matching, and never do I have one trying to push or pull the rest, they all start and run very well together, especially when pulling a train, since the weight of the train really evens out the pulling power - like the real thing, each will pull as best it can.
You just need them to be close. If one loco jumps to 15 smph on step 1 and the other can poke along tie to tie on step 1, they will not MU together well. But if one runs at 2 smph and the other at 3 smph, they will work fine as is with no firther adjustment.
I honestly do not understand this obsession with getting every loco in perfect lockstep across the entire speed range. It just makes the DC guys point and laugh at how complicated DCC is while they just grab 2 locos from their engine terminal and couple up to a train. Plus not all decoders do 28 stpeed step interpolation when fed in 128SS mode, which is all I use. There was a huge discussion in the early days of DCC that 14 steps should be plenty, since most prototype diesels only have 8 notches. All those arguing that 14 speed steps (later 28 and FINALLY 128 after being pushed by several US manufacturers) were forgetting one thing - physics does not scale. When you have all that weight of a prototypical
My check of two speed matched DCC locomotives is put them on the layout 2 feet apart. 0 to full throttle to 0, forward Direction. 2 feet apart again. 0 to full throttle in about 6 sec, then to 0, reverse direction. No coupling together, then this is close enough.
Bob Frey