o27 curved track vs. o31 loco

[GTBob]

I know a 17" loco (ex. Williams SD90, etc.) will not work on a Lionel o27 switch due to overhang of loco body hitting relay housing.  But, taking the switch out of the picture, will a SD90 navigate successfully on just o27 curved track???  I'm talking 2 pieces of curved o27 track making a 90 degree turn.  

Comments please..  Thanks..

GTBob

[MB425]

It may. I would give it a try and see what happens.

IIRC, the SD90 is a 6 axle (4 powered, 2 dummy) locomotive and while that may cause it to derail and not navigate 0-27 curves, I think it would work fine. Give it a try to find out.

[Joe Satnik]

Dear GTBob,

I looked for some old Williams fliers, thinking about the 3 axle trucks, wondering if they had center blind drivers, etc. 

Ends up the blind drivers are closest to the center of the loco, or 3rd axle from the ends.  The bolsters are centered between the first and second axle from the ends, which of course is non-prototypical. 

Measuring and calculating off screen in the product section:

Bolster to bolster:  11-3/4"

Bolster to ends of body (steps): 2-1/2"

O27 curve radius: 12.435" or ~12-7/16"  (source: AnyRail.com)

O27 tie length (width of track) 2"

Width of prototype loco: 10', scaled to model width: 2-1/2"

Overhangs,  underhang etc. calculations to follow.

Sincerely,

Joe Satnik

[GTBob]

MB425---I don't have a 17" diesel loco to see if it will work OK on the 027 curve.  Needless to say, I don't want to buy one only to find out it don't work on the curve.

Joe S.--Will look forward to your calculations--Hopefully they'll help.

Much thanks to both of you for your input. 

Actually, I was hoping someone out there in model trainland had already tried running a 17" Williams diesel over two pieces of 027 curve and would be able to comment on how the loco performed.   Anyone??

Cheers,

GTB

[jpstrainyard]

JP of Acton MA USA writes,

Hi GTBob,

I have a Willaims FP45 loco, with 6 wheel trucks. The 2 outer-most and 2 center axles are flanged and driven by the motors. The 2 inner-most axles are equipped with non flanged, non geared plastic wheels. I do run O27 and O31 tracks, but don't run switches, just loops. My FP45 will easily navigate both radius curves, without derailing, but there is noticeable overhang, but nothing serious.

Sincerely: JP

[DominicMazoch]

Engines are rated for all types of curves:  simple, reverse, and switches.  If it fails one type of curve, it flunks on them all.

[GTBob]

JP of Acton MA USA writes,

Hi GTBob,

I have a Willaims FP45 loco, with 6 wheel trucks. The 2 outer-most and 2 center axles are flanged and driven by the motors. The 2 inner-most axles are equipped with non flanged, non geared plastic wheels. I do run O27 and O31 tracks, but don't run switches, just loops. My FP45 will easily navigate both radius curves, without derailing, but there is noticeable overhang, but nothing serious.

Sincerely: JP

JP----this is EXACTLY the info I was trying to gather.  Your comment has answered my question.  Thank you very much.

Regards,

GTBob

[Joe Satnik]

SD-90/O-27 calculations:

Underhang (middle of loco): 2.73" from center rail (curve adds 1.48" to half frame width of 1.25".)

Overhang (ends of loco): 2.37" from center rail (curve adds 1.12" to half frame width of 1.25".)

Bolsters span  56.4 degrees of track curve.

Inside frame corners span 81.5 degrees of track curve.  This means that you could fit only 4 on the circle at one time.  (What a parade!) 1 loco per 2 track pieces.

Hope this helps.

Sincerely,

Joe Satnik

[GTBob]

Joe Satnik-----Thanks for your calculations.  As noted above--the 17" SD90 Williams loco should work w/ no problems on 2 sections of 027 curved track.

Regards,

GTB

[phillyreading]

GTBob,

Are you using this engine near another set of parallel tracks?
If so you will need to measure the overhang of all engines at their widest point on the outside of the rails to see how far to space your tracks. Also how much overhang does any of your other engines need?

I have a Reading T-1 steam locomotive that has an extremely large rear cab overhang and will hit other engines and cars on the parallel track going around a curve that most of my other engines don't have any problem with. Unfortionately I built my layout before purchasing my T-1 locomotive.

Lee F.

[GTBob]

GTBob,

Are you using this engine near another set of parallel tracks?
If so you will need to measure the overhang of all engines at their widest point on the outside of the rails to see how far to space your tracks. Also how much overhang does any of your other engines need?

Lee F.

phillyreading----You make some good points here.  I have two loops running two different trains.  The outer loop is where I'll run the 17" Williams loco.  The O/S tracks (curve and straight) are far enough away from the inner loop as not to interfear w/ overhang from the trains on either loop. 

Thanks much for your input.

GTB

[phillyreading]

When you have parallel tracks, especially at the corners, you have to make sure that the engines don't hit each other when going thru or passing at the curves. Sometimes as much as five & a quarter inches are needed between curves(measured center rail to center rail) even when using 031 & 042 curves. Another thing is to start the inner curve about five inches before the outside curve section of track.
I have three Williams SD-45's and I run them on 031 & 042 curves, have not tried them on 027 curves. Also have a set of Williams F-7's that I run on 031 curves. My GP-9's will run on 027 track with no problems, other than Lionel 027 switches as the housing sticks up too much.

This is my personal opion about track, I use Gargraves as their switches are very low to the ground and allow almost anything to pass thru, no clearance issues. I have had major league trouble with Lionel's O gauge switches made since 1995.

Lee F.

[DominicMazoch]

Also, there is the "profile" issue.  there are some switches and curves built with the lower O27 profile, but have wider radii.

Lionel and K-Line had O27 n 42" inch curves and switches.  I have heard of O27 profile in 72", but cannot confirm.

Marx made o27 profile for 34" curves and switches.

[phillyreading]

Not sure if there is 027 track in 072 radius.
Gargraves makes track sizes up to 120 inch radius and that will work with 027 track with just adapter pins installed. Hope that helps you.

Lee F.

[trainkrzy]

  Yes, k-line made 072 curves in 027 height. They also made 054,042,031,and 027.