# SPEED MATCHING QUESTION



## spikedrivingblues (Dec 11, 2018)

Hello, all,

I recently tried to speed match two locos for the first time. I got two BLI SD40-2s hoping they would be pretty close out of the box. One is a Paragon 2 and the other is a Paragon 3.

I only adjusted CVs 2, 5 and 6. Running them uncoupled at typical mainline speed (for my layout) the separation between them increases by an inch or so over about 40' (I model HO scale by the way).

I'm wondering if this is alright or if I need to do some more advanced CV adjusting. My concern is that there is a strain on one loco or the couplers.

Thanks


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## gunrunnerjohn (Nov 10, 2010)

I'd think that small a difference would be fine, you'll never get two to run exactly the same speed. You're talking about a fraction of a percent of difference in speed, that's as good as it normally gets unless you're real lucky!


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## Old_Hobo (Feb 20, 2014)

When you lash them up, put the faster one in the lead....


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## gunrunnerjohn (Nov 10, 2010)

With that small a difference, I suspect it won't make a difference which one is in the lead.


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## Old_Hobo (Feb 20, 2014)

Always best to have the faster one in the lead.....


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## spikedrivingblues (Dec 11, 2018)

Old_Hobo said:


> Always best to have the faster one in the lead.....


At the risk of starting an argument between you and John :laugh:, Why do you say that?

I ask because I'd like to run the consist in either direction. One loco faces forward in either direction.


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## Stan D (Feb 1, 2019)

Being the noob that I am, wouldn't it be easier on the coupler to have the faster one in the lead?


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## Old_Hobo (Feb 20, 2014)

That's one good reason to have the faster one in the lead....another reason is you don't want the faster one pushing the slower one through curves, bigger likely hood of derailing the slower one's rear truck....trust me, I know that it happens.....

No arguing that....


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## gunrunnerjohn (Nov 10, 2010)

I generally agree with the faster one in the lead. My point was with a speed differential of a fraction of a percent, it probably wouldn't make a meaningful difference.


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## spikedrivingblues (Dec 11, 2018)

Thanks for the input, guys. 

So far I haven't had any problems with derailing regardless of which loco is in the lead...hopefully I've got them close enough with the only changing low, mid and high speed.

If in the future I need to get into more detailed speed matching with these or other engines, anyone who has some info or a link to something on that I would be interested.

Thanks again


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## mesenteria (Oct 29, 2015)

If you still have problems with the two that are that close together (and that is quite close), disable BEMF in both locomotives.


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## wvgca (Jan 21, 2013)

with very little difference in the speed, the slower one in front [by themselves] will turn into the slightly faster one with a load behind them ...


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## spikedrivingblues (Dec 11, 2018)

Being so new to this i never considered that, wvgca. 

More proof that I’m a beginner; I have to ask mesenteria
What the hell is BEMF? 

Based on how the consist runs and all of your help I think
they’ re alright. I just usually try to satisfy my curiosity 
hoping for a better understanding of the hobby. Thanks


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