Min curves for steam locomotives.

[mikebaz]

Being new to the hobby I have been looking at a lot of different size configurations. Is there any limit on radius size for the larger size, say a 2-4-4-2 engine or larger?

[pdlethbridge]

If you have the space, always go with the bigger curves like 30" or better. If all you have room for is a 5'x9' table try to stay with 22" radius. A 4' x 8' would be good for 18" radius. Another thing to consider is the way the engine would look on the curves. A 4-12-2 on 22" might work but would look terrible doing it. A 4-4-0 or 4-6-0 or even a 2-8-0 would work good on 18" radius but again, if you have the space, go for the largest radius your space will handle

[ebtnut]

Mike:  I wasn't sure whether you were using the Whyte system or the continental system for wheel arrangements.  A 2-4-4-2 (Whyte) will go around a very sharp curve, maybe even less than 18" HO.  Now, if you're using the continental system a 2-4-4-2 becomes a 4-8-8-4, which is a vary big engine.  Rivarossi, and maybe some others, have made 4-8-8-4 models go around 18" curves by making both of the engine sets swivel under the boiler.  The prototypes only had the front engine swivel.  Models built that way need much larger curves. 

There are trade-offs between motive power and model railroad curves.  Most of Bachmann's equipment will go around 18" curves though some, like the 4-8-4's and the 2-10-2's suffer from appearances sake with big overhangs in the cab area.  What Paul says is true, the bigger the curve you can accommodate, the better. 

Note that the real railroads had the same issues with curves, rail weights, bridge restrictions and the like.  Specific types of power were assigned to certain portions of the railroad.  For instance, the Wabash kept a couple of ancient Moguls into the 1950's to operate on a branch that wouldn't even support a GP-9.  On the Cubres and Toltec (part of the old D&RGW) there is a steel trestle where they can only allow one locomotive at a time on it.  Double-headed trains have to stop so the first engine can cross light.  Then the second engine comes across with the train and they recouple. 

[Robertj668]

I will add one thing it is a little tight but 22" will work on a 4X8 too.
Robert

[gandoff]

Hello everyone. I have a question about the minemum turn radius for an N gauage Northern 4-8-4. I have helped build platforms with my Father many years ago for Christmas with O, S, and later on HO trains. Now,at 60 years old, i have 2 N guage trains that i am going to set up in my basement. Space is limited. i want more than 2 oval tracks . my concern is, how tight of a curve can I use for the 4-8-4 loco.

[Robertj668]

gandoff
I work in HO scale. When I have questions on what min turn radius for my HO I use the Bachmann Catalog.  So I looked up in "N" scale and a 4-8-4  specifically a J series 4-8-4 for reference. According to Bachmann is says "Performs best on 11.25" radius curves or greater."

Actually I just found on another page this
"Performs best on 11.25" radius curves or greater."
4-8-4
2-6-2
0-6-0
4-4-0

Hope this helps.

Robert

[jward]

everything in n scale performs better on curves of 11.25" or greater. in fact, i would advise against using anything less.

[gandoff]

Great thanks to You Robertj668 and jward, for your replies to my question about min radii for n gauge loco's. after reading both replies, it dawned on me that all i need do is stick with the 11.25" radius. i think all I have to do is follow the norm, whether a full curve piece of of track, or a 1/2 length  track and i think it will not matter if I make an ''S" curve. As long as I use the 11.25" radius as a norm. thanks to both of you for "kick starting" my brain.

[jward]

re: s curves and n guage. the stansard atlas switch was interchangeable with a 19" curve, thus any crossover track was an s curve of two 19" curves. they worked fine for me, running some pretty large diesels and 86' boxcars....

[Running Bear]

It also depends on what your loco is built for. Some won't go below 35" radius while at least one of the Big Boy models offer will take 18" radius although it will look absolutely ridiculous while doing it. I have a 4-6-2 that's allergic to any curve curve tighter than 24" radius while my Mehano 2-10-2 is right at home running on 18" radius.

[SteamGene]

Runnin Bear is correct, except that is who built the model.  Many inexpensive 2-8-2s will have no problem with 18 inch radius, but I have a Pacific Fast Mail C&O K-3 that is not real happy with 40 inch radius! 
Gene