Will a 2 rail passenger car run on 3 rail track ??

Original Post

Depends upon the track. Specifically the rail shape. Rounded rails, like old school tinplate or FasTrack (Upside down "U") probably not so good.

Atlas O or MTH ScaleTrax and you're probably just fine.

Dewman51 posted:

Will a 2 rail passenger car run on 3 rail track ??


1) Depends on what type of 3-Rail track.

2) Depends on how sharp the curves are.

3) Depends on what type of turnouts.

As a general rule, 2-Rail SCALE wheels do NOT track well on many "traditional" 3-Rail track systems. However, the Atlas solid nickel silver 3-Rail track, and Ross/Gargraves track seems to be more tolerant of SOME 2-Rail wheel profiles. That said, the 2-Rail wheels will ALWAYS bang/jump/drop through 3-Rail turnout frogs.

Many of the high end brass models will not handle the typical 3 rail sharper radius.    the more detailed the underbody is, the less sharp a curve it will handle.

I think the GGD heavyweights which I have would handle a pretty sharp curve.    they have much less detail underneath and are designed to use either 3 rail or 2 rail trucks.   

Another issue is coupler swing.    Typically on 2 rail cars, the couplers are mounted to the body not the truck and will not swing nearly as far on curves.

Unless you have perfect track... Don't do it.

I had a MTH Premier F7 (3 Rail) but with scale wheels.  I use MTH scaletrax.  The engine derailed on every switch.  I swapped out the scale wheels for hirail wheels and everything runs fine now.


What Hot Water said about the turnout frogs...x3.

I run 3-rail on 2-rail though , but I had  Brad at Signature Switch make my #6 turnouts specifically for my application.

I tried converting to 2-rail wheels on my rolling stock (keeping the engines 3-rail) and they ran fine around the mainline, but would derail when going thru the turnouts.  I think it's because of the 3-rail trucks and not the 2-rail wheels I put in them.  I have 1 car with 2-rail wheels and I believe the trucks were also from a 2-rail car and it has run fine so far.

I had a 3 rail layout many years ago and I slowly converted to 2-rail.    The layout was all gargraves track and switches and was flat top rail.    I was able to run my two rail stuff on it with not problems.    It was all 40 ft cars and small locos, but it worked.    I did have to add shims to the top of some guard rails in switches for the two rail stock and locos.     And of course there was a little bounce going thru the frogs.    the frogs in in 3 rail switches are built to wider standard than 2 rail and so are the guard rails.      I converted the trucks or replaced them on the freight cars.    I had a Gem 2-6-0, All Nation 4-4-0, and Gem 0-6-0 that I ran on that track.   I actually put 3rd rail rollers on the 4-4-0 and 2-6-0.   the 0-6-0 had an open frame underneath and I could not add rollers.    That started me to 2 rail as wired part of the layout for that loco.     I still have the o=6-0 and 2-6-0 but I sold the 4-4-0 when I decided to go all Pennsy.     All is 2 rail now.

As HW says, it depends. You need flat-top rail like Ross, Atlas, MTH ScaleTrax, or Gargraves.

The modern higher-end brass and Lionel's new replacement wheel sets tend to have the .145 wheel treads, so if your track has slightly wide gauge (like Gargraves Flex), you may get "drop in" derailments with the gauge. Atlas 2-rail rolling stock, MTH scale wheels, and Intermountain wheel sets (Weaver replacements) seem to work well.

Turnouts create another issue, though. The turnout can't be larger than a #5 (11-degree Ross) as the frog gets longer with #6 and #8 turnouts and the wheel drops into it. We modified a turnout with a point within the frog to compensate for this. Curve-replacement turnouts (O-72, etc.) will be problematic, especially during backing moves because the arc of the curve extends through the frog and the guard rails are ineffective with scale wheels.

Curve requirements depend on the length of the car, coupler swing, and the distance between the end sill and the truck bolster. Atlas 89-foot Trailer flats can negotiate 36" radius (O-72) curves because it has long-shank couplers (I replaced the plastic Atlas ones with metal Kadees). A passenger car with long-shank Kadees can make tighter curves than one with regular-shank Kadees. You also have to be cautious regarding which cars are coupled to each other so their end sills have roughly the same swing-out on curves to prevent one car from derailing another. All that said, when it comes to model railroad curves, bigger is better.

Car weight is another issue. You want your heavier cars up front or a bunch of properly-weighted short cars to get more flanges toward the front . The NMRA weighting recommendation is 5 ounces plus one ounce per actual inch of car length, so a 40-foot (10-inch) car should weigh in at 15 ounces. We keep a postal scale and stick-on weights at the club  as we're on a program to get all of the club cars properly ballasted (we put the kids on this one so it's taking a little longer).

You're also going have to get used to "problematic" cars that seem right, but randomly derail. That's the price you pay for living in both worlds. Sometimes making modifications to the trucks are required. On some of my Atlas cars, I take out the secondary crossbar to allow the trucks to float a bit.

Despite some negatives, the positives are:

  • The scale-wheeled rolling stock rolls better. I've tested this and it's very consistent.
  • The equipment looks better as it's closer coupled.
  • No traction tires on locomotives!
  • You'll find all of those bad spots in your layout. These are the ones that cause minor derailments with scale wheels but, in time, cause disastrous derailments with hi-rail equipment. Yes, the club members rib me about scale wheels, but like that our track is getting cleaned up.
  • Scale wheels are quieter than hi-rail wheels. This is probably related to the material and construction of the wheels.
  • You can find some really nice 2-rail cars out on eBay and from others that aren't available in 3-rail. Yes, they're expensive, but there's some nice stuff out there.

I kinda made a statement in my post above about 2-rail and 3-rail trucks (not wheels).

Is there a difference between the trucks themselves?  Should I be able to simply swap wheels sets or is there more to it than that?  I was having issues with some trucks and not with others, but I couldn't begin to tell you all the brands of trucks I have.

Wheels, or at least axles, can be different too.  Some have pointy ends and some are blunt and many times the blunt axles won't fit into certain trucks.

Most 2 rail trucks are made to NMRA recommendations which means the truck bolster sits a defined height above the rail.    This is the case with the trucks made by mainly 2 rail mfgs.     The NMRA recommendation also defines the height of the underbody of the floor above rail.    the Body bolsters on cars made mainly by 2 rail mfgs are made to these specifications.    Generally (there sometimes exceptions), you can replace the trucks from one mfg on a 2 rail car with trucks from another mfg and the couplers will still be right height and the car will look right.

The mfgs that do a mostly 3 rail business each make the truck height and body bolsters to fit their own couplers.    First on all, the truck bolster is much higher and the body bolster is thinner.    The trucks are designed to use specific couplers.    While you can change trucks from one brand to another, it usually takes some work to get the car to sit right and look right.

As for changing wheels, I have converted quite a few 3 rail cars to 2 rail, and simply done that.     Sometimes it is an easy fit.    And often it is the easiest way to convert the car and get it to sit at the right height since the bolsters are designed to work with each other.      

Up until the last few  years, Atlas trucks were wide and required wheelsets with longer axles than most.    the more recent releases are not like that.    Easiest conversion is to use Atlas 2 rail wheelsets.     Many MTH cars can use Athearn or Intermountain wheelsets.     Some however require different axles.    Most Lionel trucks require slightly longer axles than Athearn or MTH but the stamped metal truck bolsters can often be adjusted (bent) to accomodate these wheels.   

It is fun and adventure to dig into some of these conversion projects.     I have not done any passenger cars, so all my comments for conversion refer to freight cars.    The NMRA recommendations however also apply to passenger.

I bought a boat load of Intermountain wheel sets a while back and found that maybe 50% of my cars I tried them on worked without derailing going thru the "made for 3-rail" Signature Switch turnouts (code 148 2-rail) due to the frog.  I have some pretty crusty trucks on a few of my cars and I'm thinking that's what's causing the problems, just don't know what brands they are.  I haven't found any trucks for sale that don't come with wheels yet but I'm still looking.  In the mean time I've converted the few I did back to 3-rail wheels, except for the Smoky Mountain Model Works Southern gondola I put together last year which is running fine using Athearn 2-rail trucks.

I took 2 MTH F units with a KaDee hooked to 2rail, 1 REA car and 12 Atlas Zephyr cars and turned on the jGargraves and Ross switches. No problems.


CBQer posted:

I took 2 MTH F units with a KaDee hooked to 2rail, 1 REA car and 12 Atlas Zephyr cars and turned on the jGargraves and Ross switches. No problems.


Did you try backing the entire train through the same route?

Bob  - awhile back a friend bought Intermountain Bettendorf truck kits in bulk and re-sold them to friends in the MD/DC,VA area.  I seem to recall they cost less than $3/pair.  We also bought Intermountain wheel sets in bulk.   When Athearn truck prices went out of sight Intermountain trucks became my de-facto standard for re-trucking steam/diesel transition era freight cars.   The details really "pop" when weathered  and their NMRA standard height bolsters make them particularly suitable for use under Athearn, All Nation, Weaver, and a wide range of imported brass freight cars.   

CBQer posted:


Are you kidding? I only go forward.


Seriously.  Would I ever kid anyone, anywhere, any time?  Everyone knows that I have no sense of humor whatsoever.

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