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Speed Matching

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  • Member since
    November 2009
  • 36 posts
Speed Matching
Posted by tsanders1950 on Tuesday, December 1, 2009 12:27 PM

Does anyone know anything about this feature? I have a NCE Power Cab controller and when trying to set up a consist have found that some locos are running at different speeds resulting in a "pushing and pulling" motion that is somewhat annoying. Anythign you can suggest would be helpful.

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Posted by tsanders1950 on Tuesday, December 1, 2009 1:01 PM

I think I understand in theory what you are asking me to do. I know which loco is the slowest; it is an Atlas GP-40 about five years old.  I have never programmed a CV value; how is this accomplished?  Once this is done on this loco, how do I go about "matching" this one with all the others?  You indicate to use this one as the standard; how is this done? By watching the speed or just programming the new CV values for 2, 5, and 6?  Sorry to be such a pain but I am not very skilled in programming using my DCC controller.  Thanks for the information though.

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Posted by JoeinPA on Tuesday, December 1, 2009 3:22 PM

 David has given you a very straightforward procedure to follow.  Since you have not done any CV programming you should first go to the manual that came with your DCC system and familiarize yourself with the procedure for changing CVs.  Once that is done you can proceed- but trying to speed match without a firm grasp of your system's procedures for CV setting is bound to fail.  Once you have optimized your "standard" loco you can adjust the CVs of your others to speed match by following David's procedure.  Speed can be measured by timing a loco for a set, accurately measured distance or, more conveniently, by placing your standard loco and another you want to match spaced a short distance apart on a section of track and set them to the same speed set and see if they travel at the same speed or is the standard faster or slower.  The CVs of the second loco can then be adjusted and the procedure repeated until it is able to travel at the same speed at the same speed set setting as the standard loco.

Joe   

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Posted by Silver Pilot on Wednesday, December 2, 2009 6:57 AM

David,

Page mode and Operation Mode programming are Digitrax terms.

Google is good! Yahoo is my friend.
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Posted by tsanders1950 on Wednesday, December 2, 2009 11:41 AM

Thanks for your input; I tried changing the settings on Cv 2, 5, 6 on my slowest loco; i then tried changing the settings to the same on another loco and it didnt work. I guess it comes down to "trial and error" in order to match the speed of one loco to another. Good suggestion about running them on parallel tracks to try and match the speed. Good news is I only have seven locos and only want to run consists with four of them.  Some units just look better running together such as GP 20's and 38's. Kind of strange to see a U boat and GP together.  Thanks for the insight.

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Posted by CSX Robert on Wednesday, December 2, 2009 2:23 PM
Silver Pilot
Page mode and Operation Mode programming are Digitrax terms.
No, these are NMRA terms. NMRA Recommended Practice 9.2.3 describes Direct, Physical, and Paged mode programming and Recommended Practice 9.2.1 describes Operations mode programming.
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Posted by locoworks on Wednesday, December 2, 2009 3:41 PM

tsanders1950

Thanks for your input; I tried changing the settings on Cv 2, 5, 6 on my slowest loco; i then tried changing the settings to the same on another loco and it didnt work. I guess it comes down to "trial and error" in order to match the speed of one loco to another. Good suggestion about running them on parallel tracks to try and match the speed. Good news is I only have seven locos and only want to run consists with four of them.  Some units just look better running together such as GP 20's and 38's. Kind of strange to see a U boat and GP together.  Thanks for the insight.

what you do is as said above is set CV's 2,5 & 6 in your slow loco.   then in your next loco, set CV2 so you get a crawl at the same speed as the first 'slow' loco you did, it doesn't matter if the actual value of the CV is different, aslong as the actual physical speed of the loco's are the same.   then go to the CV5 ( max speed ) in the loco you are matching to the slow loco, set CV5 to say 80% of its highest setting. then set that loco going on an oval with the slow loco also moving.  run the faster loco at 100% throttle, and then set the slow loco to 100% throttle and see which is faster??  if it is the slow loco,  increase the CV5 in the faster loco to say 85% of max, and try again??  eventually you will get a value in CV 5 of the faster loco that when both loco's are on 100% throttle the speeds are as good as the same.  then a good starting point for CV6 is half the value of CV5,  then see how the two loco's speeds compare on 50% throttle settings??  if they aren't the same adjust CV6 till the speeds match at 50% throttle.  and so on!!.    even with these 3 points matched, you may still find that at say 70% throttle that the speeds are noticeably different!!   if this is the case?? to get things better you will need to go down the speed table route, which is essentially the same process, but with 28CV's to mess with instead of just 3!!  a real PIA, but made easier with computer and decoder pro.

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Posted by wjstix on Wednesday, December 2, 2009 4:01 PM

Yes there is no magic formula, it's just trial and error. It's best as noted to use a slower engine as the base or "golden engine" to match the faster engines to. CV's can be used to make a fast engine run slower, but you can't make the engine run faster than it would run on full power DC. Just take your time to get the two engines to run together at the same speed, then you can adjust CV 2 and 3 (momentum) so they smoothly start together and slowly glide to a stop together.

Stix
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  • From: Christiana, TN
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Posted by CSX Robert on Wednesday, December 2, 2009 5:09 PM
One thing I would like to point out is if you want to speed match several locomotives, don't just pick the slowest and match the rest to it. Pick the slowest one and slow it down even more(David did allude to this but I don't think he stressed the importance of it). The reason is if you don't you will most likely eventually get another locomotive that is even slower that you want to speed match to the rest, which means you would have to go through and slow all of them down even more to match the new one.
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Posted by BIG JERR on Thursday, December 3, 2009 12:36 AM

just wondering,why no one uses the speed matching method I believe it uses 28 speed steps ,and its part  of the decoder pro /jmri program and I believe joe fugate uses it too.like I say just curious

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Posted by locoworks on Thursday, December 3, 2009 1:55 AM

they do BIG JERR, i did mention at the end of my last post, but it is quite a ways up the learning curve of DCC and not everyone needs to get there to achieve their railroading goals.

 an idea i had was to build a rolling road with a DRO displaying the RPM of one of the rollers,  it would then just be a case of matching the RPM displayed on the DRO at various speed steps rather than 'eyeballing' the speeds on the rails?   a sort of calibrated treadmill for locos

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Posted by rrinker on Thursday, December 3, 2009 7:42 AM

locoworks

they do BIG JERR, i did mention at the end of my last post, but it is quite a ways up the learning curve of DCC and not everyone needs to get there to achieve their railroading goals.

 an idea i had was to build a rolling road with a DRO displaying the RPM of one of the rollers,  it would then just be a case of matching the RPM displayed on the DRO at various speed steps rather than 'eyeballing' the speeds on the rails?   a sort of calibrated treadmill for locos

 That would be a great idea. Probably pretty easy too - there are those speedometer cars that work by detecting the rate at which a strip on a wheel comes past a sensor - which could be easily adapted to one of the commercial roller systems. It's calibrated to the wheel size, in this case the size of the roller, and all you'd have to do is put a black stripe on one of the rollers and position the sensor near it. Bonus is it reads out in scale MPH, not RPM

                                     --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by BIG JERR on Thursday, December 3, 2009 9:36 AM

sorry Loccoworks, some how I missed that,I have been useing a lot glue lately. I seen the speed table /decoderpro method used on a fugate video and he makes it look so easy . when I try the other method using cv.2,5,6 I get frustrated fast ,but now I see that it was probably cause Ididnt fully understand how each cv worked and "how close is close enough"...thanks to all for there input ,very helpful ..Jerry

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Posted by locoworks on Thursday, December 3, 2009 11:42 AM

no problems JERR, i find it hard to read every post when i have the gist of a thread too Smile.  re the DRO, i would be tempted to put a larger diameter disc on the outer of one of the rollers and section into 6 or 8 with a magic marker to trigger the DRO sensor, so it would give more/better resolution per rev of the roller.

 

something you can't legsilate for with speed matching is the 'slow down' on tighter curves due to the increased drag/friction against the sideplay in the chassis.   diesels with 6 axle bogies suffer more than 4 axle bogies, and the long wheelbase 6 axle bogies on alco PA's really do put the brakes on ( talking from N gauge experience here on 9 inch curves ) this may not be as much of an issue with shallow curves, or even with a decent decoder with BEMF to compensate??

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