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@Robbin posted:

I was able to examine an M1(A or B) up close and noticed that driver 2 and 3 of 4 do not have flanges.  Silly me.  I figured that this was just a feature of my model engine and never dreamed that the real thing also might have to negotiate sharp curves and would not want all the drivers flanged (see photo).  Just for reference the K-4 does have all three flanged but it seems that the four (and assume five driver engines) it might depend on the wheel base of the drivers.  So this definitely clears the way in my mind to having as sharp as O96 or 48" radius curves and two rail engines like an M1 and J1 that I would assume also dont have to have all the drivers flanged!  Just like the real thing.

I only own two 2R Steam engines and all drivers are flanged (Pacific and Niagara 4-8-4).  I understand your excitement.  Before making the assumption that the 2R models follow the prototypes, I think it would be worth checking with 2R guys if that is the case.  Hopefully they post to this topic, but if they don't you may want to start a topic on that.

Last edited by MainLine Steam

Here are observations from my own layout

36" Radius (this is my minium, a lot of these can go around narrower)

MTH 2-10-0 consolidation

Sunset GP7  (fixed pilots)

Sunset GP9 (fixed pilots)

Sunset SD9 (Fixed pilots, six axle)

MTH F7 ABBA  (Fixed pilots, Factory Spacing)

Atlas RSD7 (Fixed pilots, six axle)

MT Train Master (fixed pilots)

Weaver RSD 12 (Fixed pilots, six axle)

Atlas RS1 (fixed pilots)

MTH Aerotrain (Fixed pilot, prototypically close coupling locos and all coaches, converted to 2 rail)

All GGD 21" passenger cars  (Factory Spacing)

MTH GG1 (converted to 2 rail)

40" Radius

MTH F7 ABBA (Prototypical close coupling)

Lionel ABBA Sharks (fixed pilots, prototypically close coupling, converted to 2 rail)

MTH L1 (2-8-2)

46" Radius

Sunset GG1 (widened slots in four wheel trucks)

MTH P5a and P5a Modified (Fixed pilots, converted to 2 rail)

All GGD 21" passenger cars (prototytpical close coupling, diaphragms touching)

Sunset M1b (4-8-2).   Center drivers blind

Sunset B70m baggage car

MTH I1 (center divers are blind from the factory)

Sunset N1 (2-10-2)

All of the above curves are hidden for asthetic reasons.   Which means equipment has to be super reliable

All of the above curves have easements

One more note: Awhile back I had a Westside J1a (2-10-4). A massive locomotive that had been reworked by Ed Rappe to go around tighter radius curves.  I set up a test track, and with easements it could easily go around 44" radius curves,  going forward and backwards. It looked a bit silly with all that overhang, but that had nothing to do with the number of rails.  Or its ability to track the 44" curves

PRR steam locomotive practice with regard to blind center drivers varied widely by class.  J1 and J1a 2-10-4's were fully flanged. PRR I1 2-10-0's were built with 3 blind center drivers, but in the 1930's flanged tires were fitted to drivers 2 and 4.  H6sb 2-8-0's had blind center drivers, while H8 ,9, and 10 2-8-0's had fully flanged drivers.  That said you'll find many classes of previously imported PRR  O scale 2 rail locomotives can with minor adjustment (like drawbar lengh) can negotiate 48" radius curves.  When in doubt about a specific model I recommend posting a question on the 2 rail forum asking about other's experience with the model.   

2 or 3 rail there is a lot to say for battery power especially since you are starting your layout

no track wiring- this is a big amount of effort saved

no track power transformers (you can simply use regulated inexpensive dc power supplies for building lights and accessories)

no track cleaning

this also opens up more options for control systems (for sure more than 3 rail)

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