Modification to a loco/tender to operate on smaller radius track?

That's going to be wildly hit or miss.  You might be able to hack some locomotives to run on a smaller diameter curve, but I suspect many simply will not be reliable.  I tried my VL-BB on O60, and it wasn't even close, no sale.  From the looks of things, the tender and the locomotive are problematic.  Other large locomotives will doubtless be similar.

I'd seriously just consider sticking to O42 compatible stuff in the short term.

 I was faced with a same problem, I was using a "small"2-8-0 locomotive all I had to do was get a longer draw bar for the tender. The locomotive without the tender would take the curves so I lucked out and only needed a longer draw bar. If I had been trying to do this with a large locomotive say a Big Boy this would not have worked. 

  Conversely, I had to change the draw bar on a 0-8-0 because it was so long there was a scale 10ft. gap between the locomotive and the tender. 

  A definitive answer to your question requires a little more information about the type of engine you are considering modifying. The wheel configuration, distance between front and rear drivers,type of draw bar etc. I just ran the locomotive by itself through the curve and it worked.

Douglas

James

Do you know what is keeping the engine from going around 0-42? Does it derail or just strain or both?

Reason I ask is one of our local repair guys has made similar modifications to some engines to get them around 0-27. I hope  something could be done . 

You mention in your post that the catalog calls for a minimum O-54 curve.  You don't say that you have tried it with O-42 and that it doesn't work.

It is my experience some locomotives will run on smaller curves than are recommended in the catalog.  This is especially true when the curve is just one size down from the recommended curve.  That is a locomotive that is cataloged to run on O-54 will get around a O-42 without modifications.  It won't get around an O-36 curve, however.

I recommend that you try the engine to see if it will get around your O-42 curves.  

Joe

ON my layout I have some O31 and O 42 curves but have put straight pieces in between the curved pieces. Does this help an engine get around a curve better ??  I am thinking of an O72 curve.

Gunrunnerjohn was right: it will be hit or miss.  

However, there are some guidelines you can use to improve your chance of a hit.

For steamers, first, try to put just the loco on a longt section (longer than the loco, O-42 curve.  If you can get all the flanged drivers (you don't care about blind drivers) to fit inside the rails, with even the tinest bit of wiggle room or side to side play, then there is a chance you can make it work.  If it won't fit with its flanges all the way down inside the rails, or does but feel like it is binding, give up.

Assuming it did fit, next try to keep the drivers engaged on the rails and put the pilot trucks onto the rails.  If they won't fit, it is usually because they don't turn at enough angle.  Often, but not always, you can take the pilots and their swing arm off and modify them to swing to more of an angle.  sometimes you can't, of the truck can't swing more anyway (it hits the cylinders or something else that prevents it.  But many times, this works.  

Now, you have to do the same with the tender, although if the loco is legacy remember you can also just run it with another legacy tender, one that will fit.  Anyway, test the tender on the O-42.  Many will work even if their loco is rated O-54 or even O-72.  You probably cannot get centipede tenders to work, but I have modified tenders that came with O-72 locos and would not go around 36 inch curves so they did by just opening up the angle the trucks can swivel.  Usually involves disassembly and the Dremel or drill again as on the loco's pilot trucks.

Now, with loco and tender working on O-42, you have to couple them so they work together.  You may have to make a longer arm between them to open up the angle between them so their corners don't bump in the sharper curve.

Good luck.

You might try Lionchief or Railking engines, even the biggest will run on 042.

I just got home from work to find all the great info in your responses. Thanks so much! I know this isn't the layout forum but the question stems from my idea to build a modular layout using 4'x4' squares so I can move it when I move (in the next year or so). This is my draft layout plan:

The outer loop has all O-42 and the inner is a mix of O-31 and O-42. My idea was to run RailKing and the odd LionChief and then I came across a chance to get a Premier ESE PS1 for $200 hence the O-54 dilemma. I don't have the ESE yet so I can't test it on O-42 but the photo of the underside has me wondering: 

The compact 4-6-4 configuration of the loco doesn't seem like a problem and the trucks of the 6-6 tender appear to have enough rotational clearance to navigate O-42. If my eyeball assessment is correct, that leaves the tow bar area as the problem spot. Then again, since my dream train is a Premier Blue Goose, perhaps I should just wait until I'm a homeowner again and build something that has a loop with O-54 as the limiting radius.

Thanks again to everyone for all the great ideas and information! I appreciate it! 

I know I tried the Big Boy on O60, and the tender wouldn't go around the curve, that's when I quit.  It has a bunch of fixed wheels, and O72 is as small as it allows.

Lee is on target, if the drivers don't fit with a bit of "wiggle room", you're pretty much sunk.

James in VA,

As a rule, the men in R&D are not the morons that most believe they are. In most cases like this it is better to trust their judgement than to find yourself all red-faced and frustrated..........See, simple fix.                                                                                                                                                                            

I have a friend who runs his VL Big Boy on Atlas track O-63 curves.  I was surprised that it went around the curves but I have seen him do it many times on his small layout.

He also runs it on the G&O garden railroad with its minimum O-72 curves.

Joe

I can assure you that the VL-BB will not go around Fastrack 60" curves.

I have the JLC BB and mine will not go through my 63" Atlas curves.  

I had assumed the JLC and V versions were the same mechanically, as far as pivot points, flanges, swivel arm for pilot, etc., but maybe not.

1) Mine would definitely NOT go through 60" fastrack curves.  

2) Niether the JLC BB or Allegheny would go through the a 45 degree (two 63" curve pieces) portion of Atlas 63". I set up my layout with two pieces sandwiched between 72" curve sections leading into them and 81" curve sections for the rest of a half circle - the arrangemet of 72-63-81 looked more natural for my terrain, and tried.  But the neither the JLC BB or the JLC Allegheny will go through that way . . .  

3) I replaced the combination of 72-63-81 Atlas with Atlas flextrack, which basically never goes tighter than 35 inch radius (70 inch curve) and ends at 81.  While installing it, I played with the track radius and those two big guys both would go through 68 and even 66, but both were very tight at 66 (there was no free play of wiggle room as I spoke about.  I think you are asking for trouble when you can't feel any side to side play.

4) I will add, that it is a thing of beauty to watch the JLC BB run backwards and forwards through back-to-back 72 curves set up in an S: an S of switches is sort of the ultimate test of "will it run on XX curves?"  And it does 72.

In general I have found that you can discount 6 inches , if you are not running through switches, : most 54" rated locos will run nicely through 48" curves, but maybe not through the curved sections of 48" turnouts. I won't promise this works, but I can't think of an exception . . . 

There are some nice premium locos that will run on O-42.  The Vision Hudson runs on O-36 - I have run it around my all 36" loop.  I could be wrong but I think it is rated at 36.  Regardless, it sticks out a bit but it runs nicely.

And the photo below shows my Legacy NYC Mohawk L2-A (it has been relabled ATSF), a really impressive, big loco, rated at 0-54, on Atlas 36 curves.  It looks, and is, very tight: I don't think it would do even 35 1/2: there is no play left here on 36 inch Atlas.  But I ran it, once, through the full half circle of 36 you see here on this loop, just this morning, to verify what I am writing now, and frankly it was so scary to watch it go through this curve, on the edge of a cliff and all, that I decided not to do it a second time to take a video.  It is among my favorite two or three locos and I will not risk it again.  You will just have to trust me on it. I have other 36 inch curve sections on this loop, and it fits on them them too, but they all go through tunnel portals so I can't run it there, beause it sticks out too wide on the outside of the curves to fit through the portals, as you can imagine from the photo.

I would not recommend the Legacy L2-A Mohawk on 36" curves and I will not promise that it runs on your 42" curves, but it is a big loco, and I would expect it too.  Maybe before buying something like that you could ask a friend who has one to try it on your layout. 

@ Lee: 

I really appreciate the thought and depth of your replies to questions, both to mine and all over OGR. All the information is practical and applicable while being delivered without snarkiness. That is a true help to those of us on the steepest portions of the learning curve.

With you being in NC and me in VA (right off I-95), I hope I'll have the chance to shake your hand and buy you a beer on one of your road trips. I'm planning to make my inaugural quest to York next month so maybe I'll meet you there!

Just call or e-mail.  I would be glad to see you.  Where off I-95?  

I live in Springfield and work on Fort Belvoir, both of which straddle I-95 immediately below the DC beltway.

James, just my 2-cents, but I think this falls into the "just because it can be done doesn't mean it should be done" category.

My layout's max curve is 42" dia. like yours. I have some 34" but have gotten away from the 27". Our Christmas layout uses fastrack with 48" and 36" curves.

All of my engines are rated for 27" or 31", and I like how these smaller engines look on the 36", 42", and 48" curves.  A junior Berk (rated for 27") looks about right on 42" curves even thought it'll handle tighter ones.

By contrast, my brother-in-law has some big, scale engines rated for 54" curves.  He originally ran them on 54" curves but felt they looked silly and has since gone to 72" and even bigger.

There are plenty of good options that are rated for 31" that will look great on your 42" curves.  Some of the smaller but still scale locomotives might be good options.

I have a Rail King 2-8-8-2 USRA that runs fine on O-31.  I had to modify the pilot truck somewhat to keep it on the rails, but it goes through 022 switches just fine.  The reason it can run on O-31 track is that the rear engine swivels along with the front engine, something a diesel.  I was fascinated that I could run this bit loco on O-31, and it doesn't look weird with the rear engine swiveling unless you look very close.

If you add 12" (60" (5 ft.) total width) you can make O54 work.

My layout.   Small room.  12'6" X 11'9"  Primary oval (horizontal) is 12'6" X 5' 

Atlas track, O54 outer with O45 inner loop.  Switches are O54 with one O45, pictured far left inner circle, and one O36 bottom siding area. There are pieces of O36 and one O27 curve, bottom siding of the picture.

First modification into the next room.  Turntable roundhouse is done 5' X 7'

Slideshow.  Click to access.

Mike,

Thanks so much for sharing your plans and the slide show. If I use five 4'x5' squares vs. 4'x4', I think I could accommodate the O-54 for the outer loop and then use O-42 for the inner loop and I think I could also achieve portability/modularity for when I move. I'm really glad you posted!  

Best,

James