Minimum radius for long freight cars

[Anonymous]

I've got a rather large home layout that I'm building with a 22" min mainline radius, doubletracked with a 24" outter main radius and there's a slight possibility I will be running through trains with 89' autoracks. I'm concerned that the 22" radius will be too tight, especially if i'm passing another train in a curve. Since I'm basing the layout on my local prototype, and there are some tight mainline curves around here, I think 22" minimum would be fitting for the layout, and it allows me to squeeze in more industrial switching opportunities, so I don't want to go with any larger minimum. What is the longest equipment I should run on 22" radius curves? and if the 89' autoracks will still work, should I extend the outter radius to 25" just to give some extra room in the curves for passing?

[tstage]

jshrade,

I have a 4 x 8' layout with 22" radius curves and only run 40 - 50' rolling stock. You might (and that's a BIG might) be able to get away with running 89' autotrack on your 22" minimum radius curve...but I guarantee you, it WON't look pretty doing it. You will have to have at least a 3" track centers at your curves in order to avoid sideswiping cars and/or structures on or along the track.

jshrade, I would encourage you to FIRST experiment by laying some track down and find out what your minimum track centers need to be on those curves in order to successfully negotiate them. Put both cars and structures on and next to the track for a realistic assessment.

89' long anything is going to have a horrendous swing. I would either increase the minimum radius of your layout or reduce the maximum length of your rolling stock. IMHO, even 50' cars on 22" radius curves is borderline as far as looking good.

Tom

[BNSFNUT]

My old layout had 22"r on it. I ran Walthers 89' auto racks. They ran ok but looked a little odd. They looked better on my wider radius.

[AggroJones]

If you have a 'rather large' home layout, why have sharp 22" curves as your minimum?
That'll stress the heck out of the equiptment unnecessisarily.

I say go with at least 25" radius. Work them into your plans industrial plans.

If you DO go with 22" AND run autoracks, you better watch your clearances!

[IRONROOSTER]

Here is the NMRA's page on recommended radii http://www.nmra.org/standards/rp-11.html For 89 foot cars in HO this would be 40". As others have noted, you may be able to run on sharper curves, but wider is better. Remember, a tight mainline radius is much larger that what we typically use. As Tom said above, set up some test track and see how they look and operate.
Enjoy
Paul

[steveblackledge]

I use 24" Radius as a minimum but higher if it will fit, you can run the big stuff but it look's out of place so i tend to run 40' to 65' cars, this is the first train i ran around the final section i did last week, there are 28 cars with KD metal wheels, not a problem, i even ran them up and down the 3.25% grade at 23" radius without incident, the only problem i had was a sloppy coupler disconecting

[Anonymous]

40" ? whoo is that a swing. But on the other side you can run anything thru there.

[Don Gibson]

Your problem is 'Overhang'.Your 85' -89' cars stick out further than 22" (inner) radius. The question becomes 'what outer radius will prevent SIDE SWIPING?

... and that depend's upon the cars. i'm afraid 'tral & error' is ahead. Start with 3" - 4" separation.

[nfmisso]

jshrade;

You radii will work fine for N scale.

For HO, think about 30" min for most plastic 89' cars.

[dinwitty]

Long cars need a wide radius coupler, longer swing, or truck mounted couplers.

You can use curves, even 18" if you use easements to gradually turn into the curve, but different sized cars can have coupler alignment problems, but as long as it has the right coupler swing, it wont be a problem.

It can work out just deal with some problem solving.

HO had to deal with sharp curves, and many makers had shorty versions of passenger cars, Athearn's RDC was not full scale length, and that was to solve curve issues to get around 18" radius.
Rivarrossi had full length cars but had truck mounted couplers, all their equipment including the Big Boy would run over 18" radius, even tho it wouldnt look right.
heck I even think I tested the Big Boy on 15" and it ran.

A lot of the newer Spectrum series locos and equipment will simply be better with wider radius however.

I am planning my layout now an I have to consider all these issues at once,
but I won't have 89' equipment as I will model only the 50's equipment.
Except for the passenger car lengths.
I always try to stay 24" radius or better where I expect serious mainline runs to happen, but where I expect only freight I could hit 22" mainline and down to 15" for industrial curves.

[Anonymous]

Well, anything larger than a 24" radius minimum will drastically change my track plan, and will force me to severely modify my benchwork in order to acommodate it. I like the looks of unit train autoracks, so what I may do is just completely start over with a new track plan, try to work in 30" radius curves, maybe shorten my industrial areas to suit, and then compare the two track plans to see which would make me happier in the long run. Thanks for the advice guys!

[rogerhensley]

Better to change your track plan now than to suffer the problems that will come if you do what you described. 30" should be an absolute minimum. 36" would be better.

[Anonymous]

When checking overhang, you have a compound overhang problem to look at.

1. Put a large locomotive on the inside curve. They typically have the worst overhang on the outside of the curve.

2. Put the longest car and locomotive on the outside curve and try and have them pass the locomotive on the inside curve. Make sure you have at least 1/8" between them at the worst point.

Obviously having only 1/8" between rolling stock as it flies past each other is tight. More is better.

Most HO equipment can traverse 18" curves, but that doesn't mean it won't look funny. I'd say you want a curve broad enough that the outside rail is not visible from the overhanging car. Once that rail starts to show its face, it start to look funny.

Mark in Utah

Mark in Utah

[nfmisso]

QUOTE: Originally posted by mark_in_utah

........Most HO equipment can traverse 18" curves, .........

Like the Athearn AutoMax, 26" min radius, and it does not look good at it.