# N Scale curve vs 6 axle locomotives



## Bikewider (Nov 27, 2020)

Good afternoon,
So I just purchased my1st N scale loco. It's a Broadway Limited CSX paint scheme in DCC. My concern is that I am getting mixed info regarding the minimum curve radius you can safely run this size loco on.
I was told don't go near 9 and try to be above 11. So I'd like to know about the 11-degree radius. I don't see ever using 9-degree radius curves, but certainly 11. 
Or, do i need to stick to 2 axle trucks?

Thank all in advance.

SK


----------



## Mixed Freight (Aug 31, 2019)

FYI, it's "inch" radius, not "degree" radius. 9-3/4" radius track is kinda' the defacto minimum train set standard for N-scale. It's fine for 4-axle locos and shorter equipment.

6-axle locos are "iffy" as to whether they'll run on 9-3/4" radius curves or not. Some will and some won't. Your best bet is to go with 11" radius curves minimum for 6-axle locos. They all seem to be okay with this radius.

If you have the room, go with even bigger radius curves yet. Your trains will run better and look better on larger curves.


----------



## JeffHurl (Apr 22, 2021)

I have a Kato SD70ace that navigates 11.25" without any trouble at all.


----------



## traction fan (Oct 5, 2014)

Bikewider said:


> Good afternoon,
> So I just purchased my1st N scale loco. It's a Broadway Limited CSX paint scheme in DCC. My concern is that I am getting mixed info regarding the minimum curve radius you can safely run this size loco on.
> I was told don't go near 9 and try to be above 11. So I'd like to know about the 11-degree radius. I don't see ever using 9-degree radius curves, but certainly 11.
> Or, do i need to stick to 2 axle trucks?
> ...


Bikewider;

First of all, get used to receiving "mixed info" on nearly any subject on this forum. The forum is made up of hundreds of individual modelers, each of whom has their own opinions. 
I agree with Mixed Freight's response, at least mostly. Certainly, I would use nothing less than 11" radius as a minimum if you want to run six-axle diesels. However, I also second Mixed Freight's recommendation to go to a bigger radius if possible.

Do you plan to run any steam locomotives? I had a personal experience that taught me the fact that "minimum radius" recommendations by manufacturers and others, can be less than accurate. I planned, and built, my present N-scale layout with a 12" minimum radius. This was based on the common belief <shared by me, that any N-scale equipment will track reliably through 11" radius curves. I figured if that was true, then using a 12' minimum radius should work out fine. Well, it did, until I bought a pair of Kato 2-8-2 Mikado steam locomotives. Kato recommended using 11" radius as a minimum for these locos. They did run through 11" radius curves sometimes, but also derailed a lot on them. They both did the same thing on the 12" radius curves of my layout. I ended up doing some tests to see what radius curve they would stay on reliably. The reliable (as opposed to minimum) radius turned out to be 16" radius. I ripped out my 12" radius curves, and replaced them with 16" radius curves. Everything stays on these larger curves quite well.

My point is not that you will have to use 16" as your minimum radius for your six axle diesels. They will probably work OK on 11" radius curves. However, bigger is always better when it comes to curve radii. Use the largest radius curve that will fit into your available space. If you later get a locomotive that has a hard time negotiating tight curves, having a larger radius than the minimum you can possibly get away with, will pay off. 
You may save yourself from my "rip them out and replace em" experience. 

Traction Fan 🙂


----------



## Bikewider (Nov 27, 2020)

Thank you for the detailed info. Is it better to just stick with quad axle locos to avoid the issue. There does not seem to be a lot of options for quad axle diesel locos


----------



## vette-kid (May 2, 2020)

I run severance dash 9s without any trouble at 11.5". I do think longer steam engine might have trouble though. I would certainly go as wide as possible, but my layout has width limitations, so this is what I have. 

Sent from my SM-G781U using Tapatalk


----------



## Mixed Freight (Aug 31, 2019)

Bikewider said:


> Thank you for the detailed info. Is it better to just stick with quad axle locos to avoid the issue. There does not seem to be a lot of options for quad axle diesel locos


Yes, if you're going to be limited to 9-3/4" radius curves, then sticking with 4-axle diesels (and shorter steam locos if desired) would be a much safer bet.


----------



## Bikewider (Nov 27, 2020)

Thank you all. I will be sticking with min 11.5. My reason for going to N scale was to have a more natural look to the layout especially when it comes to curves.


----------



## CTValleyRR (Jul 26, 2014)

Always use the widest curves that will fit. If you can do better than 11-1/2", I would. Even a very broad curve on a model railroad is very tight when compared to most track on the prototype.

But there are no guarantees of anything. Look at Traction Fan's experience. The only way to know FOR CERTAIN whether a given loco will take a curve of a given radius is to test it.


----------



## traction fan (Oct 5, 2014)

Bikewider said:


> Thank you for the detailed info. Is it better to just stick with quad axle locos to avoid the issue. There does not seem to be a lot of options for quad axle diesel locos


Bikewider;

Actually there are quite a few 4-axle diesel locomotives made in N-scale. Kato, one of the best manufacturers of N-scale equipment, makes models of EMD FTs, F-3s, F-7s, some geeps, some Fairbanks Morse units, Alco RS-1s, RS-2s & RS-3s, plus some more modern GE four-axle diesels. And that's just one of several N-scale manufacturers.
Some of these models may be out of production, but all should be available on E-bay.
If you're looking for contemporary diesel power, much of the scarcity of four-axle model diesels may be due to the simple fact that todays prototype road diesels are nearly all six axle, high horsepower, beasts. 

Good Luck & Have Fun;

Traction Fan 🙂


----------



## N Modeler (Dec 1, 2021)

Bikewider said:


> Good afternoon,
> So I just purchased my1st N scale loco. It's a Broadway Limited CSX paint scheme in DCC. My concern is that I am getting mixed info regarding the minimum curve radius you can safely run this size loco on.
> I was told don't go near 9 and try to be above 11. So I'd like to know about the 11-degree radius. I don't see ever using 9-degree radius curves, but certainly 11.
> Or, do i need to stick to 2 axle trucks?
> ...


Hi, I agree that bigger is better but I am space limited. I purchased a Broadway Limited 282 Mikado w DCC that I run successfully on a 9” curve. I have a layout mounted on a 80“ x 30” hollow door.


----------



## Thelic (Jan 10, 2018)

Kato sells 12-3/8" radius ovals with their starter track kits, commonly used with their 6 axle diesel starter train kits. I have both and they run great together, though they do look a bit unrealistic with the engine and cars protruding over the inside of the corners. I tested pulling 10 car trains uphill at 2.5% through S-bends made from 12-3/8" curves and it worked fine. This is like a torture test for trains. Would I recommend adding this feature to a layout, no. Did it do it, yes.

I designed my layout after extensive testing to have 17" visible corners and 15" hidden, and as always increasing the radius beyond these where space permitted. They look quite acceptable (to me) on 17" curves when looking from the outside and even better when viewed from the inside.

To put it into perspective, Kato's largest standard curve (turnout returns excluded) is 15".

This photo is from Kato's website. These are GE AC4400CW 6-axle locomotives. My guess is the CP is on a 9-3/4" radius. As you can see they tend to look silly before they become a problem operationally. Keep in mind that pulling is way easier than pushing if using truck mounted couplers, I doubt it would reliably push a long train through this corner.

The coal porters are likely on a 13-3/4" radius.


----------



## traction fan (Oct 5, 2014)

N Modeler said:


> Hi, I agree that bigger is better but I am space limited. I purchased a Broadway Limited 282 Mikado w DCC that I run successfully on a 9” curve. I have a layout mounted on a 80“ x 30” hollow door.
> View attachment 571961



N Modeler;

Welcome to the forum!
I'm happy for you if you're getting reliable operation from your Mikados.
In your photo, it looks like you're using Atlas sectional track & turnouts. Atlas does not make 9" radius curved track sections, as far as I know. They do make 9-3/4" curved track sections, which is actually a little bit closer to 10" than 9", and I suspect that may be what you have.

I never argue with success. If your trains run on your door layout without problems, congratulations! That's all that really matters.
By the way I've built two of those door layouts in the past. A hollow core door makes a handy base for a layout. I used 36" doors, rather than 30" but did also use Atlas sectional track, and turnouts, back then. I have moved on since, and I'm now working on my seventh layout. I now use Micro Engineering's code 55 flex track and scratchbuilt turnouts.

Keep Having Fun;

Traction Fan 🙂


----------

