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I posted this question on the 3R scale forum, but I'm not getting any useful responses. Would anyone know the flange depth on 3rd Rail, 3 rail locos--and would the wheel flanges hit the spike heads on Atlas c148 2-Rail track?


It seems to me that radio control would be a viable option to convert these 3-R steamers to 2-rail operation, but it would be more practical if I didn't need to turn the flanges down on the wheels.


Ideally I would want a deeper flange than the 2-rail versions of the locos (to help the locos negotiate sharp curves), but not so deep as to bottom out on spike heads.


Turnout flangeways will be another consideration, but I think that can be solved now that I have the ability to scratchbuild a turnout to fit my needs.




Jeff C

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I like your thinking. Have thought of it myself from time to time. You are correct that you would need larger flanges to help with the tighter curves. I don't have anything to test to give you an answer unfortunately. One thing I don't understand is in O gauge why isn't 2 rail Hi rail more popular for those folks that want big scale trains that operate on real 2 rail track, but can negotiate much tighter curves? MTH makes proto 3/2 engines that have larger flanges and blind drivers that will run on tight 2 rail track. I don't know why anyone would want to do 3RS over 2RS. It makes no sense to me. There is no technical reason to have the 3rd rail anymore. Just 100+ yrs of tradition and nostalgia.

Why cant you just run MTH steamers with Hi rail wheels on 2 rail track if it has the proto 3/2 option? How much deeper are the flanges on scale vs hi rail steamers? What is the rail height on Atlas 2 rail track and MTH scaletrax (supposedly the smallest 3 rail track)?  There cant be that much of a difference.  I think this might be a good way to run large steamers on 2 rail track without the need for 60in radius curves...might be something interesting to look into.



For what it is worth, I dug out the tender to a 3rd rail 3 rail ATSF 5032 and ran it on some Atlas 2 rail track.  It seemed to do just fine.  I think that going to radio control will become more and more common.  Not only does it eliminate all sorts of wiring issues it would also address your (and I suspect many other's) particular situation...providing an easy way to convert 3 rail locos to 2 rail without having to turn the drivers, add wipers, etc.



Quote - "I think the least of your problems would be hitting any spike heads. What about when you run those oversize flanges through a switch frog? I really don't believe that O-Scale, 2-Rail switch frogs are designed to take .095" deep, fat flanges, are they?"





I just proved to myself that I can build a turnout--and the rest of the answer to your question is about dimensioning the frog properly, and also setting a maximum flange depth and width that will work with the equipment I run.


I also build my own turnout frogs out of rail, instead of using a cast frog.


The 3rd Rail flange depth of .095 is actually closer to scale than most 3-R flange depths. A 172 scale wheelset has a depth of .063, and it works fine going through Atlas turnouts. The NWSL tinplate wheels have a flange depth of .110. I know for a fact that some Willams wheelsets are .12, so there are a wide variety of flange depths and widths out there.


Every one you don't need deep flanges to run tight curves, this has been proven over and over. If your trying to avoid having to sell all that great stuff you already have(very understandable)you have two problems,first there are no real standards in three rail, so flange widths and depths are all over the place.You cant run three rail through 2 rail points!!! The best thing that could happen is for three rail scale to adopted two rail wheel and track standards then going from two rail to three rail would simply be a matter of the flick of a switch.MTH has come closest to bringing us closer to that day but until there Premier line adopts NMRA standards accross the board the transition is painful. the difficulty is that three rail cant let go of its TOY heritage there shouldn't be a conflict toy trains are toy trains scale trains are scale models and should have the same Standereds.


(cTr...Choose the Right)      Stephen from Down Under

I would think the only challenge one would have with a 3 rail wheel set is over switches. I would think that one can use 148 rail with 3 rail wheels and tight turns but just don't go roaring around the layout.

RC the locos is an idea I have been tossing about as I have several diffferent engine wire ups. DC DCC DCS and TMCC. I saw an HO version at a LHS of a RC unit

that one can install in ones engines and all one has to do is bus his layout for the power supply. Sounds good to me. I also understand this fella that sells the RC is from the midwest. Forgot his name or business but when needed I sure I can find him.  

I'm not really looking to run a lot of 3-R equipment, but there are three 3rd Rail/Sunset steamers I'd like to have, and I doubt I will ever have 56" radius curves on any layout I'm likely to build.


I don't worry about MTH locos--as has been mentioned, the 3/2 option is available on most of those locos, and the 2-R MTH locos will generally negotiate the same radius curve as the tinplate version.


3rd Rail steamers are different--the frame is completely different on the 2-R models when compared to the 3-rail version, and those 2-rail models don't have the sideplay or clearance for tight radius curves.


Jeff C

I can tell you that the nice MTH Hudson ran just fine on my handlaid .148 track with an Old Pullman curved switch on one of the curves.  I switched it to scale wheels only because I was dissatisfied with the appearance - it got a scale frame and cylinder block, and kept its PS-2 sound.  Also got a boiler belly,which is something most 3-rail scale steamers lack.

bob2, So just to clarify... You ran your MTH Hudson with 3 rail flanges through your hand laid code 148 turnouts correct? What size flangeways did you use? I did mine by eye... Did you happen to measure?


Has anyone tried to hand lay a turnout that would allow operation of both size flanges? It sounds goofy I know, but I can't help but think that some people who are in 2 rail but have smaller radii might want to run larger MTH Proto 3/2 engines with the 3 rail flanges because the center drivers are blind.  Or would it just be easier to turn down the 2 rail flanges and blind the center drivers yourself?


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