Large Scale Central

O gauge two rail question

Other Scales
#1

As a continuation of my day dreaming I am wondering what I can get away with when it comes to O two rail curves.

I was told what the “rules” were in G. And turns out there is a lot of wiggle room. I’m assuming the same is true in O. Everything I read seems to suggest minimum radius for O is 72 inches or in other words a 12 foot diameter. I dont have a single curve that large in G. All of mine are 8 and 10 foot diameter and works just fine with smaller to even medium sized equipment.

The stuff I got from Steve is all smaller to medium sized stuff. I am really hoping I can get away with 6 ft diameter and if need be 8 foot. Am I asking for too much.

#2

Here’s an easy formula to remember. Measure the distance of your longest piece of equipment in inches ( or calculate). Take that number and times it by 1.5. That will be the absolute minimum curve that can be ran with body mounted couplers. It won’t look good but it will work ( but just barely).

2x the longest length is better and will run reliability. 3x and it starts looking better, 4x and 5x are ideal.

This comes from the 1st issue of MRH magazine.

Edit to add. Measurements equal radius.

See link for magazine article.
https://model-railroad-hobbyist.com/magazine/mrh-2009-Q1/legacy_download

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#3

Only the largest MTH, Williams, and Lionel locomotives need the 72 inch diameter curves, which is why that is the diameter of our test track at the store. Many of the medium and small sized O gauge locomotives will negotiate 36 inch and 31 inch diameter curves. a 54 inch diameter curve is a good happy medium. Just remember that diameter is measured from track centerline to the opposite track centerline.

Best, David Meashey

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#4

Devon,
I just won this Faller e-Train set recently in an auction for $16. I post it here to make the point that is (a) is narrow gauge [IIn600, or Spur II (1:22.5) narrow 600mm gauge, I think], and (b) the curves are 30" diameter, or 15" radius.

Faller eTrain Cabin Fever 061224
Faller eTrain Cabin Fever 0612241562×1135 293 KB

So it all depends what O-gauge trains you are running. In the UK, SM32 locos tend to be 0-4-0s and will handle the Faller track. PECO Setrack in SM32 is 30" radius, or 5’ diameter which is better for larger locos, but no where near the 72" you quoted.

https://peco-uk.com/collections/sm-32-32mm

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#5

I will have to dig out what I got and see what it’s lengths are. It’s way bigger than that set Pete. What I am most worried about is the coaches i believe that set has some long cars. I acquired a passenger train and a freight train. Will just have to take a look at what I have. If I can do 72 Diameter (not radius) I could make it work easy. I understand that it may not look great but I don’t have the room for a prototypical standard gauge o layout.

#6

I double checked the article… I was wrong.
2x will barely fit
2.5x reliability if same length
3x coupler swing needs to be 50%
3.5x less toy like when viewed from inside curve
4x less toy like when viewed from outside curve
5x most reliable and can use scale draft gear box ( not very much coupler swing).

Well worth reading the article. After all it’s free. :stuck_out_tongue_winking_eye:

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#7

Craig I appreciate the info. But I am not looking at what SHOULD be done and instead what CAN be done. I know a nice prototypical rr would look great. I don’t have the space indoor or out. What inwant to achieve is what can I get away with without running into trains that won’t run

#8

I know you’re looking at what can be done. And I’m giving you a formula on how to figure that out.

What can be done at the minimum is the 2.5x radius. That’s the bare minimum that stuff will work.

Anything below that won’t work.

Say 24" is the longest car. 2.5 x 24" = 60" radius. A 45" radius won’t work no matter how hard you try. A 55" radius won’t either…

Now a O scale car isn’t going to be 24".

Take a 8" car, x 2.5 = 20" radius.

The formula works because it’s so simple. If you can go bigger great, but the bare minimum is going to be just that.

I wanted to post the other ranges just so people can see the other side of the coin. :stuck_out_tongue_winking_eye:

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#9

I will definitely take your guidance to heart. I will break out the passenger equipment and measure. I have no doubt they will be the longest cars.

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#10

Devon, I can only tell you what my club standards were (circa late 1970s). Mainline minimum RADIUS was 72, yard and industrial was 54 radius. The narrow gauge (3 foot) was 48 on the main and 36 in yards/industries. These provided very reliable operation and minimum grief. Even with long heavyweight passenger cars they looked good. Back then we didn’t have the 89 foot modern cars we have today. I am sure they have updated that to accommodate the modern stuff available today.
FEIW

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