# surging when consisted



## lownote (Jan 3, 2008)

I've got two identical locos--both 2-8-0s built on aristo Mikado platforms. They both have QSI cards in them. Both have _indentical _settings and they have been speed matched.

When they are consisted, they "surge." The lead loco slows and speeds up so much that you can see the trailing loco spinning its wheels. I posted this on the QSI yahoo list and got the suggestion to disable BEMF. I'd rather not do that because I like the way BEMF effects the sound. 


Anyone else out there have a suggestion?


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## lownote (Jan 3, 2008)

I just tried disabling BEMF on the lead loco, and that seems to have done the trick--now the two locos seem to doublehead very well


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## jimtyp (Jan 2, 2008)

Yes, BEMF is known to cause havoc with consists. Got a video of your double head


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## George Schreyer (Jan 16, 2009)

When both locos have BEMF enabled, they BOTH want to set the speed precisely. No matter how closely you try to speed match them, you won't get it close enough. The solution on some decoders is to reduce the intensity of the BEMF feedback such that it doesn't try so hard to hit it's target. 

The other way is to turn BEMF off on one of them. That loco with BEMF sets the tone, the other just follows along maybe with a little pulling or pushing. Your solution demonstrates that.


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