Mainline track spacing

[NW Mailing List]

Jim,

Instead of the constant K = 9 for HO scale, plug in K = 30 for O scale 
(measurements in inches).

Generally, for track centers (TC) on curves and R = radius:

TC/curve/ = TC/tangent/ + (K / R)

should work for different scales and units of measure by scaling the 
term "K" below.

For all terms in millimeters:

TT3 (1:101.6) scale, K = 4300

TT (1:120) scale, K = 3000

For all terms in inches:

N (1:160) scale, K = 3

TT (1:120) scale, K = 5

HO (1:87) scale, K = 9

S (1:64) scale, K = 17

O (1:48) scale, K = 30

The disclaimer. . .
I have only tested this empirically in HO scale. Your results may vary 
with scale and tolerances of wheel gauge, track gauge, track centers, 
and overhang.

Grant Carpenter

On 4/21/2023 6:08 AM, NW Mailing List wrote:
> Grant,
> What would be the formula for "O" scale . I too will be running the 
> Jawn Henry and a Class A , and Y 's.
> Jim Liddle
>
> *From:* NW-Mailing-List <nw-mailing-list-bounces at nwhs.org> on behalf 
> of NW Mailing List via NW-Mailing-List <nw-mailing-list at nwhs.org>
> *Sent:* Thursday, April 20, 2023 2:37:49 PM
> *To:* N&W Mailing List <nw-mailing-list at nwhs.org>
> *Cc:* NW Mailing List <nw-mailing-list at nwhs.org>
> *Subject:* Re: Mainline track spacing
> Grant, thanks for that formula for track spacing in curves. I have 
> seen guidance and rules of thumb that fall with in the range that 9/R 
> produces, but nothing that concrete.
>
> Matt Goodman
>
> > On Apr 20, 2023, at 10:24 AM, NW Mailing List 
> <nw-mailing-list at nwhs.org> wrote:
> >
> > Mike,
> >
> > Per N&W Standard L-334 (1928, rev. 1947), track centers are 14 feet 
> or 1-15/16 inches in HO scale. Rounded to 2 inches on tangents, add 
> 9/R on curves, where R = the radius in inches. For example, the track 
> centers in a 36-inch radius curve are 2 inches plus 9/36, or 2-1/4 
> inches. Which main is less or more than 36 inches doesn't matter, as 
> long as the centers are at 2-1/4 inches.
> >
> > This has been verified in testing and allows for the over/out of 
> scale slop in track, running gear, car body swing, overhang, etc. The 
> worst case sideswipe potential I can imagine is the inside overhang of 
> the Jawn Henry on the outside main versus the outside overhang of the 
> Class A boiler/smoke box on the inside main.
> >
> > Grant Carpenter
> >
> > On 4/17/2023 3:06 PM, NW Mailing List wrote:
> >> Does anyone have info for mainline track spacing? Is it found on 
> track charts?
> >> From pictures, it appears to be approximately 13 feet center to 
> center, but it's difficult to get a precise reading from this picture 
> taken at an angle.
> >> Thanks
> >> Mike Rector
> Browse the NW-Mailing-List archives at
> http://list.nwhs.org/pipermail/nw-mailing-list/
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