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@Ted R posted:

According to the label on the box in the picture Kenneth posted, it operates on 72" radius curves (O-144). Sounds about right.

Yep exactly correct ….this is where folks tend to mislead themselves, ( along with a little play on words ) …..lots of folks pick these kind of engines up cause they think they got a deal, only to find out they won’t even think about navigating O-72 track…..the OP would need the equivalent of O-144 ( as you mentioned ) to make it run right….if the OP is absolutely in love with the engine, his only hope to get it around O-72 curves is a drive block swap,…you’d be surprised how many of those scale wheel locomotives I’ve swapped drive blocks on…..then their deal wasn’t such a deal,….😁

Pat

Last edited by harmonyards

Pat,

I’m not sure what a drive block swap is. Does that mean swapping out a couple of the wheels with ones without flanges?

No sir, the drive block is the entire chassis …..the term drive block is what MTH parts calls the chassis…..they sell the chassis with the drivers ( wheels ) already pressed on,…..a drive block swap requires no special tools, ….it’s just nuts, bolts, & screws….if you’re truly in love with your model, ( that’s understandable) a drive block swap is a viable option…..the scale driver drive block has very good resale value on the secondary market…….you can get very close to breaking even as a DIY project …..I mean don’t get me wrong, it’s a bit of work, but there’s nothing really hard to do, …it’s just a lot to do….

Pat

Pat,

Okay, I understand what you are saying. One other question. Would the new drive block be scale wheels or the larger Flange 3 rail wheels? I’m building a 2 rail layout so I would need scale wheels.

I didn’t look at the forum ..I see now you’re on the 2 rail forum…..….the drive block I was mentioning is for 3 rail hi rail track,…for 2 rail, you’re gonna have to stick to the drive block you have and make your curves pretty generous ….about  all you can do …

Pat

Or! you could carefully remove the flanges on the centre two drivers, with a fill. This is crude, but don carefully, quite effective. It was often done on older two rail models to facilitate the use of smaller radius curves.      cTr....( Choose the Right )

Good suggestion, or if he knows somebody with a lathe, pop the center drivers off, and spin them down…….if they’re turned down just right, the tire contact patch will actually be wider, and more than likely still ride on the rail,…….

Pat

MTH locos I have seen do not have sprung drivers, so even if the tires did not stay on rails, they would not drop in and cause a derailment.    Of course It has been a few years since I Have handled one.   I did an extensive review for a magazine on the PRR J1 2-10-4.   This is the same chassis as the C&O T1.    The 2 rail version I reviewed would not go around 70 inch RADIUS!   

All drivers were flanged.    However, they did not build like typical brass 2 rail locos.    The typical locos I have are imported brass models.    The have jointed side rods.    The side rod is the big rod that connects all the drivers to each other.    These locos have joints at each crank pin.    This allows the center drivers to shift in one direction sideways while the end ones shift the other direction to help going around curves.     This is like a real steamer.   The drivers all move as far sideways as the frame on axle bearings allow.

The MTH engine I reviewed had solid siderods.    Think of a rectangle/parallelogram.    The axles had a lot of sideways play, but could not move in opposite directions.    With rigid side rods, when the front axle moved to the right (for example), the side rods forced the other axles including the rear one in the opposite direction.    The rods did not allow both end axles to adjust in the same direction to meet the curve.     With all wheels flanged, it made a very stiff loco.  

My opinion was that it would not cost that much more to joint the side rods to allow sharper curves.    The engine was pretty nice other than that which meant it was limited to very wide curves.    My layout has maximum 52 in radius curves.    I could not run it anywhere other than on straight track.

So another complicated solution whould be fabricate new side rods.  

This is not my recommendation...but I remember seeing an HO engine, I think it was a PRR T1 but not at all sure, that was "articulated".  Each set of drivers could pivot separately. The pivot points were close to or at the second set of cylinders.  I believe also that this arrangement could be "made rigid" via screws for those in HO with layouts with very large curve radii.  If you like PRR T1's, and who doesn't, this arrangement would permit operation on sharper curves, but I suspect that appearance would be abysmal on typical 3 rail Lionel 072. What this type of design WILL do is reduce the minimum radius on which these locomotives will run.

I am continually amazed by builders that announce 3 rail engines with very long rigid driving wheelbases, like the UP 4-12-2, and the ATSF 2-10-4's with 74" inch driving wheels.  These engines are less acceptable of curvature than even a large articulated.  Even a UP Big Boy has a shorter rigid wheelbase (although boiler overhang on curves is another potential problem).

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