O gauge rails

[Peter Crawford]

Hi, can 2-rail locos be used on 3-rail track?

[Crosland]

It have read of it being done but, if you need to ask the question, I wouldn't bother.

 

You need to start by considering:

 

Are the two rails of the 3-rail track connected together?

 

Do you want to run 2-rail and 3-rail at the same time?

 

Is the 3-rail system AC?

 

Are the wheelsets isolated on the three rails stock so as not to short the tracks together?

[Peter Crawford]

They would kind of be at the same time, but it's DC for MTH and Ace Trains type products (with small radii) but on some parts, 2-rail could be good.

[F-UnitMad]

On plain track - I'd say a guarded "possibly". But over points - forget it.

[Peter Crawford]

What's wrong with the points? 2-rail simply means no 'shoe' on the central rail, doesn't it? Could someone explain the way the 3 rails work? On 2-rail, one rail is the pick-up at a certain polarity and the other is the return at a different polarity, no?

[F-UnitMad]

3-rail wheel standards are so coarse this is especially true with points. 2-rail wheelsets just won't run smoothly through them. I'm on an American O Forum where 3-railers ask this question quite often. Mindyou, the way they carry on about perceived "issues" with 2-rail being a constant source of short circuits (???!!!) you'd think HO & N didn't exist!

 

Edit: as for the electrickery, 3-rail is fundamentally different to 2-rail. With 3-rail the 2 'normal' rails are the same feed, & might well not be isolated from each other. The middle 3rd rail is the opposite feed. Being AC maybe '+' &'-' aren't appropriate as they are for 2-rail wiring. The only thing in favour of such a system is the bulletproof current supply to the motor; stalling due to poor electrical pickup is almost unheard of.

Edited June 26, 2018 by F-UnitMad

[AndyID]

If you want to run 2-rail locomotives on 3-rail track your best bet could be to convert them to 3-rail operation. An even better bet might be to convert them to battery power with radio-control.

[DCB]

It depends entirely if the running rails are insulated from each other .  Some 3 rail track has the running rails insulated from each other and some does not.  Connect your controller to the running rails. Put a loco on the rails, see if it moves.  You could check for continuity with an ohm meter, but that's a bit technical.

Radio control with on board battery power works on 2 rail, 3 rail and even the kitchen floor with no rails, as does clockwork come to think of it.

 

Edit. I read an article from the 1960s where an existing layout had been changed from 3 rail to 2 rail. previously all 3 rails had been insulated and the two running rails had operated proper track circuits with non insulated stock.  They agonised over whether the improvement in appearance would outweigh the loss of the track circuits which  think also operated some of their signals.

 

Non insulated track makes building pointwork so much easier, I use battery power outside in 00 and use mainly scrap points bought for a quid or less each bodged back together with no worries about insulators, frog polarity or the like, much like Network Rail actually.

Edited June 27, 2018 by DavidCBroad

[AndyID]

It depends entirely if the running rails are insulated from each other .  Some 3 rail track has the running rails insulated from each other and some does not.  Connect your controller to the running rails. Put a loco on the rails, see if it moves.  You could check for continuity with an ohm meter, but that's a bit technical.

Radio control with on board battery power works on 2 rail, 3 rail and even the kitchen floor with no rails, as does clockwork come to think of it.

 

Trix knew how to do it. You could even run three trains independently on the same section*, but that was a very, very long time ago. We've come a long way since then, maybe

 

EDIT:

 

* but only if you bought into the idea of common return.

Edited June 27, 2018 by AndyID

[Peter Crawford]

The only known modern image manufacturer is MTH, who use 3-rail and tolerate sharp radii. But as a heritage railway, some UK steam stock is appreciated e.g. Ixion Hudswell Clarke.

[F-UnitMad]

The only known modern image manufacturer is MTH, ....

Which 'outline' - USA or European?

Atlas do some modern US locos, in both 2- & 3-rail. The 2-rail models can take 36" radius curves. Which reminds me - don't forget that 2-rail measures curves by radius, & 3-rail measures by diameter, & measures to the outside rail, not track center-line. This means an 0-36 curve in 3-rail is not the same as a 36" curve in 2-rail.

[Peter Crawford]

European

[Chimer]

The key point is surely the one others have made already, i.e. are the normal running rails connected electrically.  If they are, you have a immediate short if you apply power for conventional two-rail running.  And I'm guessing that with any commercially produced 3-rail point, the two running rails meet physically (and therefore electrically) at the frog, as there's no reason to introduce any isolation and the accompanying need for frog switching for reliable pickup.

 

If you added a third rail to conventional two-rail track (which I suppose might be possible for some people  ), it would work, just as back in the day Tri-ang's catenary wires provided an alternative supply and allowed one "overhead electric" and one "other" to run into one another be controlled separately on the same section of track.  Anyone ever tried Southern-style third-rail with the third rail powered?  

 

Chris

 

[AndyID]

Tri-ang's catenary wires provided an alternative supply and allowed one "overhead electric" and one "other" to run into one another be controlled separately on the same section of track.

 

 

Ah, but Trix allowed three trains to run into one another. Two controlled from the rails and one from the overhead line. Not only that, they bridged the gap between 00 and H0, but that's a different story entirely.

Edited June 30, 2018 by AndyID