Turn out # specifications

[Anonymous]

I've searched with no luck. Can any point me to where I can find the specications for a #6, 8 etc turn out? Is it the radius (equivelent) or how far the frog is from the points, frog angle, etc. Seems that the frog angle and frog distance would relate to the radius.

Reason for this: I know my track radius, so what switch (er, sorry, 'turn out') do I choose for the track radius used?

Jeff

[dave9999]

Jeff,
If you look at a Atlas snap switch, you will notice that the diverging track is 18" radius.

Numbered turnouts are a little different... the diverging track is straight past the frog.
So, numbered turnouts do not have a radius. Good luck, Dave

[johncolley]

The number for a turnout relates to the frog angle: how many units out for 1 unit divergence. It doesn't matter if you use 1/4 inch or 1 centimeter or any other unit as long as it's the same. #6= 6 units out for 1 unit of divergence, #8= 8 units out for 1 unit of divergence, OK? Check out John Armstrong's book, "Track planning for realistic operation" for lots of great info. It is a good investment in enjoying your railroad.

[dehusman]

The only switches I know that are built on a "radius" are Peco and some Atlas snap track switches. By the time you get to a #6 or #8 the tracks diverge at an angle, there is no "radius" through them. The diverging route is straight throught points, curved between the points and frog and straight from the frog on.

Dave H.

[rrinker]

And if you want to know the angle, it's ARCTAN(1/<frog number>)

So for a #6, it's ARCTAN(1/6) ~ 9.4 degrees

Or a #8: ARCTAN(1/8) ~ 7.1 degrees

More trigonometry than you wanted to remember....


--Randy

[claycts]

My $.02 the only thing that does not comply to the above is #6 or such Curved turnout they are the same ratio 6:1 but based on a radius. Source for that would be a Walthers Catalog. this will give you the 2 radi involved in the turnout.

[Anonymous]

My thanks to John Colley and R Rinker (p.s. thanks for the trig solution :)

After looking at Marklin Z and comparing to quite a few N-scale Atlas Code 55 and Snap code 60 + Peco and others, I've seen curved thru to the end and what I remeber from the HO days: curved thru the frog and then straight. Man, I tell you how much I searched the Internet and the forums for whatever wording would get me turn-out specs. Figured I'd find an NMRA standard somewhere.
Got my idea of the factors from a friends prototype documentation where it listed the radius of the curve (point to frog section) and the angle of the frog. Took the 400+ ft radius x12 =inches / 220 for Z and got close. But I think R Rinker's Trig will get my CAD a bit closer. Marlkin uses 490mm/13.25" full radius in their switches, no straight ends (I remember even cutting off Atlas 20+ yrs ago for this ?) but their sectional track is 220mm (8.75") and 195mm (7.75")! In laying out my module, I was trying to use CAD and roughing it but I find that it will be much easier to just order the switches and use the worst case 220mm (8.75") to model. I'll then replace the sectional with closer to 12-13" flex to keep the radius more proto (that's 36" to you HO'ers). [:D] Switches on the way!
Thanks again for the help !

[rrinker]

Yes, those angles should get you close enough to be honest about what fits in a given space. Atlas has two flavors of HO track, the Snap Track which has curved frogs, and Custom-Line which has normal angle frogs. This is what you remember - the Snap Track turnouts are made to fit in with the sectional track which was why they included that short piece of 18" radius curve with them. The curved leg with that extra piece exactly matched a regular 18" radius curve section.

--Randy

[rogerhensley]

There is an NMRA RP for turnout dimensions, but you won't find it listing radii. You can see them at http://www.nmra.org/standards/consist.html Just run down the page to the RP-12 series that gives turnout dimensions.

[turbine682]

Cool info on the NMRA site - Thanks --Ed