Mainline Curve Radius

[NYCentral1]

After thinking out a track plan, it looks like I'm going to go for a double track mainline as part of my layout, and right now I'm looking at being able to get a 28" radius for the outer main and a 26" or so for the inner. Do you all think that's enough?

i want to run some passenger cars, mostly on the outer 28" main only, and the largest engine I'll ever have will be 4-8-4.

[Anonymous]

To me that looks like plenty. In my plans anything over 24 inches is best. Check your track spacing to make sure your big stuff can get by each other. If there is room for larger even if only 2 inches go for it.

I own a BLI 2-10-4 and to me that thing will squeak out a 24" radius only if the track is "flat" and in good condition.

[Don Gibson]

28"r. and 26"r.

That should work with 98% of the Steam out there and 100% of the diesels.
Stick with #6 turnouts for Steam and mainline and #4's for Diesel yards,
There are few engines that won't navigate the above.

NOW if you're going to run (brass) 4-10-2's ,,,,,,,

If you are going to use a 'single' Crossover, I recommend a #8's (for speed). Remember to wire the inner loop in reverse polarity separated by insulated rail joiners. Using 2 Power Paks or DCC? Makes no difference. Clockwise Polariiy becomes counter-clockwise polarity on the other loop.

[tstage]

NYCentral1,

Boy! That's great that you can go that big! (I'm know that's tiny to some of you out there.) I would love to have curves greater then 22" radii but until I build an around-the-wall layout, that won't happen.

The only thing I would encourage you do consider would be to increase your center-to-center track distance from 2" to 2-1/2" on the curves. 2" will probably be fine on the straight sectons running parallel with one another. But you don't want to be side swiping any of your locos or rolling stock as they bound around the curves with only 2" centers. Longer locos and rolling stock need the added distance to conpensate for the swing outward..

In other words, better safe than sorry. What part of te NYC are you going to model?

Tom

[IRONROOSTER]

The NMRA has a standards page http://www.nmra.org/standards/s-8.html for track centers. Keep in mind that the clearance problems with passenger equipment are to the inside of the curve. 80-85' cars on your curves may require more clearance than 2". Even though your current equipment may be fine, allowing a little extra for the future might be a good idea.
Enjoy
Paul

[Leon Silverman]

Here is an interesting point of reference. I placed a branchline passenger car on an E-Z track 35- 1/2" radius curve and the coupler rode outside the outer rail. The 2" radius curve difference mighjt be fine if you run onmly ore cars on the inner track.

[rrinker]

Running cars longer than 70-75' WILL be a problem with 28" and 26" as the curve radii. I originally planned to use 30" and 32", but some testing before actually laying any track showed that this was a problem for full-length passenger cars. What I eneded up doing was makign the inside curve ALSO 32", but starting it 2" in from the start of the outer curve. The middle of the curve is about 2 1/2" apart, and the cars just clear.
2" spacing on the straight portions is fine.

--Randy

[CP5415]

QUOTE: Originally posted by rrinker

Running cars longer than 70-75' WILL be a problem with 28" and 26" as the curve radii. I originally planned to use 30" and 32", but some testing before actually laying any track showed that this was a problem for full-length passenger cars. What I eneded up doing was makign the inside curve ALSO 32", but starting it 2" in from the start of the outer curve. The middle of the curve is about 2 1/2" apart, and the cars just clear.
2" spacing on the straight portions is fine.

--Randy

Really? Problems with full length passenger cars?
I have 22" curves & have had no problems with Walthers 85 footers even at 3/4 throttle behind my Proto PA.

Gordon

[jrbernier]

Gordon,
Randy is talking about track centerline spacing, not overall speed. With 26" & 28" radius curves, I would start the 26" curve about 1/2" before the outer 28" curve; this will get you to the 1/2" spacing at the top of the curve. Even that may not prevent side-swipes! Using 25 1/2 for the inner curve would give you clearance. The best bet would be to setup some flex track on a sheet of plywood and test with both tracks having those long cars.
I have a yard lead that parallels the main track around a 30" radius curve. The yard lead is about 27 1/2" radius due to clearance for a signal. I am glad I did that as I would have had problems with long passenger cars hanging over the inside of the curve....

Jim Bernier

[rrinker]

Exactly. If you tried double track with 22" and 24" radius curves, they WOULD hit each other.
I'm quite surprised you managed to get them to go around 22" radius curves and stay coupled. I have about 6 of those new Walthers cars (actually, they're my father in law's, he's the passenger nut), and they would NOT go around 22" radius curves when I had a test loop set up. Individually, yes, but coupled to a loco, or each other, no way.

--Randy

[Leon Silverman]

Randy:
If you have a curve that the cars will negotiate individually by not coupled together, you have discovered the necessity for transition curves.

[rrinker]

Yes and no - that's right at the limit, so 22" with transitions might work - since Walthers says right on the box, 24" minimum radius. Older Walther's cars (the classic kits) aren't going to take 22", easements or no, unless you construct some sort of swinging coupler arrangment like the new cars have on them.

--Randy