Author Topic: Speed Matching  (Read 1198 times)

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Speed Matching
« on: July 30, 2014, 09:15:52 AM »
What is the easiest way to match the speed of two locos.

Thank you


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Re: Speed Matching
« Reply #1 on: July 30, 2014, 02:32:28 PM »
What is the easiest way to match the speed of two locos.

Thank you

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Re: Speed Matching
« Reply #2 on: July 30, 2014, 03:17:04 PM »
Well, this ain't the DC forum…    :D

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Re: Speed Matching
« Reply #3 on: July 30, 2014, 05:01:52 PM »
What is the easiest way to match the speed of two locos.

FWIW, nothing with DCC speed matching is "easy".

I'm not saying it can't be done, just that it takes time and effort, and the results can vary considerably.



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Re: Speed Matching
« Reply #4 on: July 30, 2014, 05:34:35 PM »
First of all this is the best thing to do as soon as you have 2 locos and more !!! So much fun to run a KATO with an Atlas finally with matched speed locos !!!

Here is what I did :
I measured an 8 feet stretch on the layout ( which is 1,280 feet in N scale ) , my freight locos are supposed to go from one point to the other at 70 smph. in 12.5 seconds , that is for the max speed ( CV5 )
For the mid speed at 35 smph. it is supposed to do it in 25 seconds . ( mid speed is CV6 )

The value for CV5 and CV6 is between 0 and 255 .

CV6 mid speed
I usually start with the mid speed , I am using my computer to  program the value on a programming track using the free program JMRI Decoder Pro available on internet , I find it faster this way but you could use your handheld controller depending of which system you use .
I always begin with a value of 60 for CV6 . Put back the loco from the programming track ( PT ) a couple of feet before the measured 8' section .  I run the loco with the throttle at 50% and time the loco between the 2 points , if it's less than 25 sec. than I put back the loco on the PT and add some more value to 60 , maybe 10 more and redo the timing again . If it's too fast you lower the value programmed before .

CV5 ( max. speed )
Basically the same , except starting with a value of 130 for KATOs and 255 for Atlas loco and others .

It's never the same value for 2 locos even when they are from the same company and batch ... It does not take much to have a difference .

It's easier to measure the time than trying to match another loco . This way all your locos will be match together .

I would be a lyer if I tell you that it's perfect forever , it's not and you will find out that after a while you will have to readjust locomotives .

Locomotives that you don't use often will tend to go slower at first and then after 5 minutes or so the speed will get back on par or so with others .

While you are at it , you should program the momentum for acceleration and stopping . On mainline locos I put a value of 3 to both CV3 and CV4 .

If everything goes wrong you can erase everything you did and put a value of 8 to CV8 . ( default settings )

It's a good thing to keep your programmation on writing somewhere , which I never did ...
After al I have only 135 locos programmed ...

Some of my locos cannot obtain the max speed of 70 smph . but the mid speed is obtainable which is fun for switchers mix in a consist of mainliner .
« Last Edit: July 31, 2014, 09:53:57 AM by trainforfun »
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Re: Speed Matching
« Reply #5 on: August 05, 2014, 05:10:04 PM »
1 - Decide what you want the speed (MPH) to be at 100% - 75% - 50% etc.
2 - Get the calculator fired up and convert MPH to 1/4 times  (900/mph = 1/4 mile time)  900/50mph=20sec
     90MPH=10 sec 60MPH=15 sec etc.
3 - Measure off a 1/4 mile of track (N-scale 99", HO scale 182")
4 - Clear all speed tables and Vmin/Vmax/Vmid values
5 - warm up the loco (cold locos run noticeably slower)
6 - start timing the 1/4 miles, adjust the throttle until you get the time you want for the 1/4 mile
7 - to calculate the speed table setting (or Vmax/VMin/Mnid) multiply the %throttle setting by 2.55

Say you want your loco to run 70 MPH at full throttle.
Adjust the throttle so that your loco covers the 1/4 mile in 12.85 sec
Record the throttle setting (for example 67%)
Take the 67 and multiply it by 2.55 --> 170.85   
Set Vmax or step 28 of your speed table to 171 (no fractions allowed in the decoder)
Do the same for Vmid (step 14) and Vmin ( step 1) and you should be very close

You could do this for all 28 steps of the speed table or do a few (1% 25% 50% 75% 100%) and eye ball it in between.

On my locos step 1% is between 3 and 5MPH, 25% is 20MPH, 50% is 35MPH, 75% is 60MPH for main line freight & passenger & helpers and 40MPH for switchers, 100% is 75 for helpers and main line freight, 90 for passenger and 45 for switchers.  This allows you to MU any 2 locos below 50% (think switcher moving a road loco onto its train) or add helpers on the main line as long as you keep the speed below 60MPH.