Articulated Clearance Concern?

I have 0-72 on the outside and 0-60 on the inside. I run the Hiawatha with 19 inch cars on the inside and a bigboy on the outside with no trouble.
At the apex of the curve I'm right at 3 1/2 inches center rail to center rail which may be a little close but no problems so far.

David

I should have said, I plan on having a double main line (072 and 081 - if AtlasO). 

DPC - Thanks.  Just curious though - doesn't 060 and 072 mean you have a 6" clearance center to center?  And when you say the Bigboy is on the outside, does this mean the boiler is swinging out and away from the 060 track?  If so, how much clearance would you say you need to maintain outside the 072 track to clear the boiler's path?

well I say 0-60 but actually what I did was I used 0-72 sectional track on the outside and flex track on the inside so it may be 065 or 0-66 on the inside although it is those measurements I posted above sorry.

David

Are you saying that, regardless of what your curves measure, there is truly 3.5" clearance center to center on the curves, and that your 19" cars on the inside curve don't scrape the cars passing on the outside curve, or...?

yep they don't scrape. I love to run trains in opposite directions . I don't run the Big Boy on the inside because the cab will hit BUT I do regularly run Hiawatha 19 inch cars on the inside passing a consist of MTH heavy weight 18 inch madisons on the outside.

While everything was still in the building stage on my layout I did some experimenting
Since I was sorta locked in as to the diameter of the outside track 0-72 being the largest I could go with I wanted a large figure 8 just inside these 2 outside loops
So I laid my 0-72 track and temporarily fastened my inside track to see if I had enough clearance.

I do recommend you do this as well with the longest engines and rolling stock in your collection . it makes it nice when you don't have to worry if that new big engine you bought is gonna wipe out everything. 

David

I agree.  I have a bunch of big scale articulated and long passenger cars and at 4.5 inches, probably even 5.0, they may occasionally meet where they shouldn't.  Six inches (as in the difference between 84 and 72 diameter curves) isn't a whole lot of comfort zone, actually - they come pretty close - but it works.  

Yup - I too use O-72 and O-81 by Atlas O and an articulated engine on one track will whap one on the next track - even a non-articulated one..... the way you solve this and get the 6" spacing is to start the track with the O-72's curving before you start the O-81 curves..... stagger the start of the curves a little..... Makes sense?.....  

John and Lee

I don't have 4 1/2 clearance  I have 3 1/2 center rail to center rail.
So far I'm running 18 and 19 inch passenger cars and articulated engines regularly in opposite directions.
Never had one hit yet not even close. so it will work. I think though the best rule is if you have the room .....use it.

David

The longest overhang that I have ever seen on an articulated is on my 3rd Rail

Z-6 4-6-6-4; I presume the MTH edition must be the same or so.

The actual locos had enormously long smokeboxes (poor coal in the Northwest,

and a long smokebox helps in some way - not sure - draft, maybe?), and my Z-6

4-6-6-4 cannot go places that my Y-3 or even my SP AC-9 Lima 2-8-8-4 can.

I would not be shocked if the snoot on these things out-protrudes that of the UP 4-8-8-4.

Just FYI, for those considering a purchase.

If you plan to run large scale articulated steam engines on the inside (072) and 18 inch or longer cars on the outside (081), you will have a problem.  In order to give extra clearance on such curves and to keep the nice concentric look of Atlas curves, I placed a short straight section of track in the middle of the 081 section of the 180 degree curve.  You would need to find a length that gives you the clearance you need.

Thus far it has been OK with an extra inch of clearance (5 1/2 inches) but if I were to go to 20 or 21 inch cars, more distance would be needed.  (By OK, I mean they just barely clear)

Good luck and happy railroading,

Don

PJB

When the Atlas 3 rail track system came on the market O gauge die cast articulated steam locomotives were a very new thing.  Atlas designed around older standard "big" locomotives like the scale Hudson.  Four and a half inch spacing is fine for Hudsons but inadequate for articulateds, some electrics, the UP coal turbine and scale length passenger cars.  You need the six inch spacing of O-72 and O-84 to run all current O gauge equipment.

Take a look at this thread for more details.

https://ogrforum.com/d...ent/2415514336571810

Since Atlas doesn't offer O-84 sectional track and the flex track is hard to work with you might want to look at Ross/Gargraves or ScaleTrax.

Thanks so much for all for the inputs.  Lucky I stumbled over this in chatting with Steve (from RCS).  I mean, you'd think this issue would at least be addressed in the various track planning/building a toy RR books published by Kalmbach! 

I don't have any articulateds yet, but do have 19.5" passenger cars.  Unfortunately, such wide spacing could mean a double main that doesn't look like a real double main, as the tracks would be way too far apart.   Back to the $#@*&^% drawing board.  Wonder if easements would help, so that the beginning and ending of a curve doesn't need to be any more than 4.5" center to center? 

Peter

Easements make a big difference.  Besides, your trains will run much smoother.  Any time I listen to Greatful Dead, the next thing I know, the trains are doing 102 SMPH, and the easements keep things running smoothly.

But, I don't yet have really long cars or articulated engines.  Waiting for York!

In case you are wondering, a dual consist pulling 25 cars at 102 SMPH is kinda loud.  I don't do it for very long.

Mike

Peter,

Easements will not solve your problem, since you will still have the "big overhang" issue throughout the entire curve.

For what it's worth, on my layout, I went 5" to 5 1/4" track spacing (all Atlas O), and have absolutely NO ISSUES with running full scale 21" passenger cars, nor the largest articulated steam locomotives on the market. I have never had a clearance problem with any of my Sunset/3rd Rail largest articulated models (UP 4023, 4-8-8-4, C&O H-8 2-6-6-6, or NP Z-8 4-6-6-4), nor any of the MTH/Lionel die cast articulateds.

Also, I think any one would be hard pressed to tell that small difference between a double track main line at 4 1/2" versus 5" to 5 1/4" spacing, especially once your scenery is installed.

Mike,

I'm jealous - wish I was doing York.  Good luck locating an articulated on your want-list.

Kind of surprised you're running at 102 SMPH when listening to GD.  Would have assumed GD elicits running trains at a calm, relaxed 5 SMPH. 

So...guess Armstrong's books are as good as it gets for technical guidance for easements?

OK - thanks again to everyone for the very helpful insight and advice.  As a newbie to the hobby that's been burning the midnight oil on learning all the things needed to build a scale pike (can't believe what a learning experience this has been!), I can't tell you how grateful I am for a forum like this and all the experienced hobbyists willing to offer help.

Peter

I too was worried when I first got into O gauge.  I read alot the books I could find for advice but what worked for me was just experimentation: I did a lot of "playing" with  temporary configurations - I'd screw them down but do so knowing I would be taking them up very likely.  I often was so unsure I would not run my trains put only put them on the track and see how locos and 21" cars on adjacent tracks fared to each other. 

I use only Fastrack - that may have something to do with what I learned

Which is: never have less than six inches between centers between 48" or 60" curves, or between 60" and 72" curves, or 5.5 inches between 72 and 84.  The ruling cases (extreme situations that created these rules) on my layout is a JLC Big Boy and a Challenger or Allegheny on adjacent tracks (coming in oppsite directions).  I literally built my two big loops to this rule: two JLC Big Boys pulling 21" cars cannot create a collision anywhere, anyhow - but a miss by a a mm is as good as a mile.  And ni places I have only about a mm.  I figured there will never be any loco worse on overhang than a Big Boy.  Sure hope the Centipedes don't prove me wrong.

However, I have a 21 foot straight where I run the Fastrrack with no more than 1/2" between the edges of the plastic roadbed: about 3.5 to 3.75 inches between center rail centers.  I have to ease into it from the 6" spacing in curves at the ends, which I do by using short track section (1.25 inches) between curve halfs to space out the curve.  I do all this only in the "back" of the layout -- portions that are rather far from the viewer, so the compression of space and the uneven curve radii aren't obvious.  I have no problems although at times, there is a bit of drama because it looks like some of the big locos come awefully close to one another (because they do).