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> Double heading - consists in America
RichardTee
post 5 Jan 2012, 20:31
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I never intended to use consists on my layout but Santa brought us a Hornby OO gauge Mixed Freight DCC set which, although simple, can be set up to use consists. As my grand-daughter wants to run the two locos together I thought I should find out a bit more about how a consist works. Iíve put this in the N gauge section because my layout is N gauge with an NCE PowerCab which is obviously more flexible than the Select which comes with the Hornby Mixed Freight set. I hope some people in the OO section also read the N gauge threads.

Take a hypothetical consist which comprises a fast express steam loco being helped up an incline by a relatively slow tank engine. The motor / gearbox for each loco are different and the settings of CV5 (Maximum Voltage) and CV6 (Mid Speed Voltage) are different because of the characteristics set up for each loco.

Would the above example mean that one loco would be constantly slipping or is there some Ďmagicí feature which links them electronically together? Do CV5 and 6 and possibly CV3 (Acceleration) and CV4 (Deceleration) have to be matched in order to run a consist successfully?

The Hornby Mixed Freight set probably avoids some problems because, I assume, the motor/gearbox combinations in each loco are similar, the factory settings for CV5 and CV6 are similar for both and there is no facility in the Select controller to alter them. However, it obviously be possible for a faster express loco to be used in a consist with either or both of the Mixed Freight locos so the same problem could exist.
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Richard Johnson
post 6 Jan 2012, 03:02
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*** Your biggest problem is that hornby decoders won't let you speed match properly as they simply do not support adjustment of Cv 2, 5 and 6 or speed tables.

Your scenario describes banking - where one loco helps another - for this its usual to keep both engines under independent control although having a similar low end speed curve does help.

for consisting/double heading then yes, the locos must run together comfortably - because you can't adjust things easily with the select and can't adjust them at all with Hornby decoders anyway, double heading will only really be reealistically/smoothly practical with similar locos - sorry.

If you DO have non-hornby decoders you can easily set them up to work well together using the Powercab - the trick is to use CV2 so they both start at the same time, CV3 to adjust the low end aceleration rate so its similar and CV5 to make the higher speed range (above the mid step) the same or close.

ALWAYS change the faster loco so it matches the slower one... the opposite simply isn't practical and results will disappoint.

You MAY find that two locos fight a bit if they both have back EMF - if you use ours or a couple of other brands you can set Back EMF so that it works as it should but will turn off automatically once the loco approaches running speed so loco's will run more smoothly in consist.

regards

Richard


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RichardTee
post 6 Jan 2012, 20:11
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Thank you Richard, you have reinforced my suspicions about the Hornby decoders. I'll try a consist with the Hornby locos anyway to see how we get on. At a push I could always upgrade to better decoders.

As far as my N gauge locos are concerned, they use Lenz Silver Mini, CT Electronik or Uhlenbrock decoders so if I want to use consists I can change the required CVs using the PowerCab which, incidentally, I chose after reading about it on your site. In practice, I can't see myself wanting to use consists.
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