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2 Rail Brass O Scale Steam Locomotives on 3 Rail Track System

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2 Rail Brass O Scale Steam Locomotives on 3 Rail Track System
Posted by Locojunkie on Wednesday, October 25, 2023 8:09 AM

Hello Everyone, This is going to be a dumb question of sorts, my question is I am interested in buying a Brass  2 Rail O Scale Steam Locomotive. Can they be ran on my O scale 3 rail layout? 

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Posted by Flintlock76 on Wednesday, October 25, 2023 8:14 AM

Hey, the only dumb question is the one you won't ask!

As to your question the answer is no.  Two-rail O Scale uses a different operating system for electrical pick-up so without that third rail pick-up assembly on the locomotive's centerline that two rail engine's just going to sit there and do nothing.  Interestingly though the wheel gauge (distance between wheels) is exactly the same as regular O. 

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Posted by Locojunkie on Wednesday, October 25, 2023 11:19 AM

Ok, thanks for the information. I didn't think so, but I need to check and be certain. Thanks again. 

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Posted by Flintlock76 on Wednesday, October 25, 2023 12:31 PM

You're welcome!

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Posted by philo426 on Wednesday, October 25, 2023 2:07 PM

But the flanges are somewhat smaller .

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Posted by philo426 on Wednesday, October 25, 2023 5:44 PM

The chrome wheel set is scale...

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Posted by MidlandMike on Wednesday, October 25, 2023 8:05 PM

Flintlock76
Two-rail O Scale uses a different operating system for electrical pick-up so without that third rail pick-up assembly on the locomotive's centerline that two rail engine's just going to sit there and do nothing. ...

The outer rails on 3 rail track are the same polarity, whereas, I understand that the rails on a 2 rail system are opposite polarity.  Wouldn't putting a 2 rail loco on 3 rail track cause a short?

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Posted by lion88roar on Wednesday, October 25, 2023 10:49 PM

Well... the answer here is a bit difficult.

If you want to run 2-rail on a 3-rail system you 'can' do that depending on the track system. You would need a track system where all three rails are isolated, then you could run wire the center and one outer rail using say 'Common' and the other outer rail using 'Hot'. You will NOT be able to run both at the same time on the same track, and if you 'cross' those two outer rails you will cause a short.

In short - it is never recommended to do this. You WILL, at some point, run a 3-rail engine on that 2-rail setup and likely damage your transformer and/or the engine.

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Posted by wjstix on Thursday, October 26, 2023 3:48 PM

MidlandMike
Wouldn't putting a 2 rail loco on 3 rail track cause a short?

No, because the wheels on 2-rail engines and cars are insulated, so a current can't go directly through them. On 3-rail equipment, the running rails are both the same polarity, so 3-rail doesn't have to be insulated. 

So if your 3-rail track had the middle rail positive and the running rails negative, all that would happen with the 2-rail engine is...well, nothing. It's getting negative power (so to speak) on each side, but no positive power since it doesn't have center-rail rollers.

However, putting say a three-rail boxcar with metal wheels / axles on two rail track would create a short circuit. One rail is positive and the other negative, and the 3-rail cars wheels aren't insulated so the current would pass through the axle from one rail to the other.

 

Stix
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Posted by pennytrains on Thursday, October 26, 2023 7:19 PM

It would be best to change all the wheels to use the larger flanges of traditional style.  Third rail pick-ups could possibly be mounted on the tender trucks but you would need a tether to the locomotive.

Gargraves track has wood ties that provide the insulation you'd need to switch between 2 and 3 rail operations.  A simple switch (I use a big ceramic knife switch) would allow you to keep the current going the way you want it.  I use this setup to switch my track between AC and DC power supplies.

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Posted by palallin on Thursday, October 26, 2023 9:49 PM

It can be done.  Use a 3-rail track with both square railheads and electrically isolated outer rails.  One of our club layouts does it using Atlas O track.  We switch between the two using the  wiring for the power sources themselves as the failsafe:  only one or the other can be hooked up at any one time.  The track will accomodate scale wheelsets and traditional ones.  It is expensive but not only possible:  it's downright desirable.

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Posted by palallin on Friday, October 27, 2023 7:04 AM

Full disclosure:  we didn't install any switches, so I don't have a report on making them work.  I've heard of it being doen but we haven't yet tried it.

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