Does anyone operate MTH on 2 rail?

I have reviewed and looked at 2-rail MTH steamers.   However, these were not 3-2 conversion.

Basically, the 2 rail MTH steamers I have seen require very large curve radius because they have rigid side rods.   The siderod is the big one that connects the drivers together.    On real locos and all brass I have ever seen, this rod is jointed at a crank pin on each driver.   This allows both the front and rear drivers to slide slightly sideways in the same direction for going around curves.    With the solid siderods on the MTH and also other mfg diecast locos, the rear drivers must slide in the opposite direction sideways from the frontones, reagardless of sideplay.   this is hard to explain, but if you take a loco and put it upside down in a cradle and slide the front drivers to one side, you can see what happens.    This only only applies to locos with all flanged wheels.   If the 3-2 has blind drivers, this issue goes away.

Now as for frogs and guard rails, the large flange may or may not cause a problem.   Usually the rail spacing in the frogs and guard rails on 3 rail switches are wider and deeper than 2 rail.   In most cases, 3-rail switches are designed for the bottom of the flange to ride on the bottom of the gap in the frog.   On 2 rail switches, the design is usually for the wheel tires to ride on the rails and just bounce over the much smaller gap at the frog.   I am not familiar with Atlas O switches, so I can't comment on how their frogs are built, but that is what you should look at.   You could probably get Gargraves 2 rail switches that would work.

Just my opinion but, I can not imagine those huge "pizza cutter" flanges operating successfully on any good quality 2-Rail SCALE track & switches.

I got a Hudson about ten years ago, and it ran fine on my code 148 2-rail layout.  I did not like the looks of the flanges, and wound up making a new frame with Lobaugh drivers.  But it ran fine before i converted it.

I also ran the factory Challenger and NP Northern here, as part of a product review.  They too worked just fine.  I have only one switch - a curved Old Pullman switch - and it gave them no problems.  The TIU worked on both AC and DC, just like they said it would.

Prior to the 3-2 production, one could purchase 2-rail locomotives from MTH.  The only problem I noted with them was an occasional brake shoe short circuit.

And yes - larger locomotives require larger radii - that is always true unless you seriously compromise the appearance.

     inside loops are 2 rail, all MTH except Hi nose gp35 Atlas(tail end of video) converted to ps3.

https://youtu.be/W_9J-KSpK3s

    @ beginning CSX BNSF 4 engine multi unit
    @ .55 West bound Guilford Pan Am  5 engine multi unit
    @ 1.54 East bound Guilford 2 unit switching track

I was trying to explain that locos with one-piece side rods require larger radii than locos with articulated side rods.   I have 8 drivered USH mikados that have no trouble with 48 inch radii.   but I had  diecast 0-8-0 switcher with much smaller drivers that had much trouble with it.   If modelers pay attention to this detail, the mfg will soon understand it also. 

I'm not sure if Robert E is asking about the scale wheel version (-2) or the high rail version (-1). I've had no problems running the scale wheel versions on Atlas track but I must confess that I haven't tried to find the minimum radius for the locomotives I own. 

When I had a small layout with 49.5 min radius track I had no problems with my MTH 4-4-0 but of course I know that is a very small locomotive. I believe my MTH Pacific will handle that radius. 

I agree with what Jim is saying. If MTH would build their locomotives to handle a somewhat tighter curve it could open things up in 2rail. Maybe not a lot but a little. Admittedly I am an MTH fan but I am a little leery of buying one of their larger steam locomotives due to the radii requirement.

Guys, this input is just great, just what I was looking for, thanks so much.

Anyone else got some tips or experience with the large flange wheels on 2 rail track? 

 Flange 3 rail wheels freight cars short out on my atlas 2 rail turnouts.

I have run MTH 3/2 hi-rail locomotives on Atlas Code 148 track on both AC and DC. They work, but turnouts get dicey because of how 2-rail turnout guard rails and frogs are set. Hi-rail wheels have the flanges set inward to widen the wheel tread and have problems going through un-modified 2-rail turnouts. This was done to allow them to handle those O-27 and O-31 curves without the flanges binding. As for the increased flange size, they'll ride up on the base of the frog but can make it through in most cases.

Back in 2009, I opted to buy MTH 3/2 locomotives with scale wheels and run them on 3-rail track. On well laid (no kinks or twists) flat-top 3-rail track (Gargraves, Atlas, MTH, FasTrack) they do well, subject to curve restrictions of 36" (O-72) or larger. Four-axle diesels are more forgiving than six-axle. I have a scale-wheeled Hudson which does fine on 36" radius, but a Northern would require larger curves -- around 54" Radius (O-108) as I recall. They will take issue with curve-replacement 3-rail turnouts (O-72, etc), because the arc of the curve extends through the frog and the guard rail gap isn't narrow enough to pull the axle over enough.

If you're going the MTH 3/2 route, I'd advise going with the scale-wheeled versions and installing the pickup rollers if 3-rail is required (don't forget the switch). I have plenty of videos up on YouTube regarding scale-wheeled equipment on the club layout.

As for me, I'm leaning toward a 2-rail switching layout in the house and a 3-rail loop-runner outside. It's on hold until I relocate.

Hope this helps some.

I'm not sure if one or the other is an anomaly but I have 2 MTH 2 rail Js that have no problem whatsover negotiating 48" and even lower with the solid rods. That is a 4-8-4. Maybe possible consideration should be given on a case by case basis for engine type.

Does  your engine have blind drivers on the center sets?    That would certainly do it. 

Unless MTH has changed their designs which is possible.   I have not checked one out in a few years.

My first AC-8 had one piece side rods for a long time, before I learned how to make clevised masters for lost wax casting.  Driver wheelbase was never the limiting factor.

4-8-4s and 2-10-4s should never expect to operate much below 72" radius - the compromises in appearance near lead and trail trucks are not suitable for scale appearing models. I should note that the NYC Hudson I mentioned above had seriously undersize cylinders and a missing tail beam.  It was otherwise a good looking model.

I have 2 of the MTH 3-2 steam engines with scale wheels instead of 3 rail wheels. One is a USRA Light Mikado and the other is the WM H9. All scale wheels are flanged. An since I only had a 3 rail layout at the time, the H9 went around O72 (36 inch radius) without a problem, even with all of the wheels flanged. So I think diameter of the drivers and the wheel base of the engine factors into the equation as well.

It definitely factors in. According to Mike Pitogo, the scale-wheeled Big Boy can make it through 36" radius for the same reason -- short driver wheelbase with structural compromises for 3-rail (narrow cylinders and no tail beam).

The J has 70" drivers which are smaller than many other Northern types, and that may explain why it will negotiate smaller radius than other Northerns, Texas and other long wheelbase types. But knowing that bandofan can run the H9 and the Mikado on 36" and Pitogo with the Big Boy tells me that the anomaly is with the MTH switcher PRRJim notes.

I'm pretty sure they all have the solid rods but maybe the rods have tighter tolerances on the little switcher for some reason. Whatever the radius limitations of the switcher, those limitations clearly do not extend to some other MTH models with even longer wheelbases.

To all,

Having converted many MTH steam locos to 2 rail by machining scale tires, perhaps the most important detail of the mechanism that allows the model to negotiate a small radius is adequate lateral motion in the front and rear driver axles.  Five axle drives are hard to get around sharp curves.  Four axle models should be no problem but I advise against curves smaller than 54" radius for 2 Rail.  My first O Scale layout had 48" radius curves and would handle a Mikado and Pacific with no problems but it did not look to good to me.  Using small steam switchers or diesels you can get away with 36" radius if that is all you are going to operate.

Joe Foehrkolb