I am in the process of planning/test fitting track on my HO scale layout and I have a turnout question.
Would I run into problems routing my mainline through the divergent path of an Atlas #8 turnout?
I usually run my main's through the straight portion of turnouts, however space issues would make this difficult without major changes to my track plan.
The turnout would follow 16" of straight track coming out of a 1/4 circle 24" radius curve. Following the turnout I will have 12” to straight track going into 1/8 circle of 24” radius curve.
My largest locomotives are BLI 2-6-6-4, MTH 2-6-6-6, PCM 2-8-8-2, Proto2K E8s. They all handle 24” radius curves without issue.
Chris
A #8 is broad enough that your models should have no problems taking the diverging route at speed, as long as the track that comes after is nice and straight. Where you enter into problems is launching into an S curve (turning back to parallel the original track) right away. It's OK if the turnout is the start of a gentle curve in the same direction, but a sudden curve back puts sideways stresses on the cars that could result in derailments.
--Steven Otte, Model Railroader senior associate editorsotte@kalmbach.com
Assuming I looked at the right cell in the table (HO tab) the NMRA RP attachments show the #8 turnout curved track has a 60+ inch radius. No problem. Like any turnout, ensure it lies flat (no twists). See RP-12 attachments.
http://nmra.org/index-nmra-standards-and-recommended-practices
Paul
Modeling HO with a transition era UP bent
Sounds good.
Thank you for the quick replies.
I have a #6 using the divergent as the main. It leads into a wide curve, I have had zero problems and would think a #8 would be even better. My santa fe and reading T-1 steamers have no problem thru the turnout. I have never had a derailment at this turnout.
floridaflyer I have a #6 using the divergent as the main. It leads into a wide curve, I have had zero problems and would think a #8 would be even better. My santa fe and reading T-1 steamers have no problem thru the turnout. I have never had a derailment at this turnout.
Mike
I believe the prototype rails avoid divergent mains like the plague. It's one thing to crash across diamonds at speed, but their approaches are almost certainly tangent for several tens of meters/yards prior to the actual crossing.
Yes, it's true, one side of all axles is necessarily going to negotiate a point going through a turnout, whether at speed or in slow order, but crossovers and divergents for passenger trains doing upwards of 40 mph are in the order of #18 frogs and higher. This is impossible in all but the very largest of layouts.
Now, for the real world of layouts and running scale trains: I had two such situations on my second layout, and they ran very well. As long as I kept the points on my Fast Tracks hand-built #8 turnouts tight to the stock rail, I could zip my J Class, Niagara, and other fast engines and passenger consists through their diverging routes without a hiccup.
In several places I had Peco Streamline #6 turnouts built into the main, but only on the through routes. I did get the occasional derailment at the frog, not the point end, and it didn't matter what train type or engine type was being passed over it...it varied. I think that part was quantum mechanics, a field in which I am hopelessly inept, and not likely to improve.
Put a switch machine on it that will hold the points closed tight.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
You might also want to explore using the large radius Peco double curved turnout
Dave Nelson
Due to space limitations I use the diverging side of a #6 at one end of my passing siding. The other end of the siding is the straight route. My layout is an ISL with diesels so using the diverging route is not a problem since speeds are relatively slow.
As Selector says, the railroads will avoid having the main line go through the diverging side of a turnout if at all possible. But there are rare cases where the preferred method is not possible, so it does happen.
Putting most traffic through the diverging side has several drawbacks. One is that it is impossible to superelevate the "curve", resulting in speed restrictions and extra wear on the outer rail. In the facing point direction there will be a lot more stress and wear on the switch point than when running straight through. That is why at the end of double track it will usually be the train leaving the double track that uses the diverging side.
Others have already provided their experience in the model world.
John