Turnout #/Radius Question?

Discussion in 'N Scale' started by Metro Red Line, Nov 9, 2006.

  1. Metro Red Line

    Metro Red Line TrainBoard Member

    Forgive my ignorance as I'm a recent convert to N from HO...

    But in N scale is there a chart somewhere which shows the radii from the curve of a given turnout number? For example, what is the radius of a #5, #6 or #7 turnout in N scale?
  2. Thirdrail

    Thirdrail In Memoriam In Memoriam

    Radii of Turnouts

    There is no radius of a numbered turnout, the track through the frog and beyond is straight. The turnout number is the proportion at which the rails diverge from the frog. A number 7 turnout diverges one inch for every seven inches, while a number 4 diverges one inch for every four inches. This is the same in any scale from G to Z.

    The only commonly used turnout in N with a radius is the Atlas Snap Track turnout, which is 19.5 inch radius. :cat:
  3. Flash Blackman

    Flash Blackman Staff Staff Member TrainBoard Supporter

  4. jlbos83

    jlbos83 TrainBoard Member

    Peco turnouts, with the exception of their newer US prototype versions (someone correct me if I am wrong), do have a radius because they are curved through the frog (which I have read follows European prototype practice, though I have not confirmed this authoritatively).

  5. EricB

    EricB TrainBoard Member

    Are you asking what radius correspond to each turnout to make a crossover or a ladder or such?

  6. Metro Red Line

    Metro Red Line TrainBoard Member

    Yep, petty much. I'm making my track plan and especially trying to find out how much of a curve I would need for yards and double-track mains.
  7. Triplex

    Triplex TrainBoard Member

    Actually, there are two radii for a turnout: the closure radius and the substitution radius. The closure radius is the actual radius of the points and the rails before the frog, and determines what equipment can run through. The larger substitution radius is the continuous curve you could splice the turnout into smoothly.
  8. BarstowRick

    BarstowRick TrainBoard Member TrainBoard Supporter

    Red and all tuned in,

    I've thrown this fish out here before and got some negative feed back. That's ok.

    What you read above is correct. However, if you want a simple way to determine the radius compatibility of a switch take a piece of prefab track IE., 11' radius curve place it over the switch starting at the points, over the frog and to the diverging or curved part of the switch. This solution will not be 100% fool proof but it will help you determine which switch to place on a curve enabling you to leave the main straight into a siding or secondary main.

    I am waiting to hear someone explain the geometery approach to solving this problem. As much as I like geometery it can be perplexing at times.

    Most N scale switch providers will provide radius equivalents either in the instructions provided or on their websites. Worth checking it out.

    Have fun and give the info sharred by all particpants here a try. Bring back your resolution and keep us posted.
  9. Grey One

    Grey One TrainBoard Member TrainBoard Supporter

    What type of track are you planning on going with?

    Over all I'd suggest you pick up a one left and one right turnout, Make a few cardboard templates and lay them out. If you were using Kato I have photographs building ladder and compound ladder yards..
  10. porkypine52

    porkypine52 TrainBoard Member

    I wouldn't use a turnout as part of a curve. You will end up with car trucks picking frogs on turnouts. Especially if you attempt to shoe-horn a #4-#5 turnout as a substitute for portion of a curve. PECO is based on European standards for trackwork, and the way I understand, they allow for curved frogs on turnouts. In the US most railroads have staight track through the frogs.
    It's your layout, you can do with it what you want. But spend the $ and time to put the BEST possible track work in the beginning, your trains will run like they should, and stay on the tracks
  11. Glenn Woodle

    Glenn Woodle TrainBoard Member

    You may be thinking of the #4 Atlas or Bachmann EZtrak turnouts that can subtitute for 1 curved track piece in a layout?

    If you get Bachmann EZtrak, be prepared to use a file to fine tune it. Their turnouts are notorious for causing derailments. About the only good feature is that they are power routing. They have no flexibility in a layout so that a pair would make a crossover without making a sharp Scurve.

    The #4 Atlas are somewhat better. At least a pair can be used to make a decent crossover. A #6 Atlas would be better. Ntrak may have a table to show how to use various turnouts. They may even have full size templates of common turnouts so you can see the difference between them.
  12. Metro Red Line

    Metro Red Line TrainBoard Member

    Thanks, that's a good idea. I'll do that.

    I'm using an unorthodox method for track planning-- since I just came over from the HO world, I'm using my old Atlas HO snap track for drawing my track plans on the layout. Why? Because HO track is exactly the same width as N roadbed and the NMRA standard clearance width for N. And since Atlas snap track comes in 18" radii, I have my minimun mainline radii set right there. I just draw the outlines of the HO track on the layout and have the N roadbed follow the outlines.

    Anyway, I'm planning to use ME (concrete ties) and Atlas code 55 for the mainlines (the Atlas go in the tunnels) and ME code 40 for the yards and sidings. I also plan to use ME and/or Atlas turnouts.

    I'm sort of turned off on using Peco turnouts since they are jut a faux-Code 55 track (actually code 80 buried in the ties) and joining them to true code 55 rails results in some rail height inconsistencies.

    Another question, for those of you with #7 turnouts, if you connect a LH and a RH together to make a crossover, how far will the track centers be?
  13. Gordon Werner

    Gordon Werner TrainBoard Member

    FYI ... high-profile wheels act differently on the ME code 55 track than they do on the Atlas Code 55 track
  14. Metro Red Line

    Metro Red Line TrainBoard Member

    Yeah I just read the thread. But apparenty since I'm just starting out and have only 5 pieces of rolling stock with all low-profile wheels, I don't think that would be a problem. I model modern era and since most of the stuff I model is relatively new with low-profiles, no biggie. If at all, I would just retrofit any pizzacutter cars I get with low-profile wheels
  15. BarstowRick

    BarstowRick TrainBoard Member TrainBoard Supporter

    To Porky and all tuned in,

    I thought the same thing until I lived for a short period of time in Dayton, Ohio. There the CSX main leaves todays N&S straight main on the curved or diverging side of the switch.

    Here in Southern California coming out of the LAUPT is a number of mains that take the diverging part of the switch to arrive or leave the station. Many of these switches are considered to be high-speed switches, some have a moveable frog that actually closes the gap reducing the potential for a derailment. You'd have to custom make the moveable frog... for N Scale applications.

    You can do the same with your model railroad. However, I would recomend using #6 as the minimum and move up into #7, #8 & #9 switches. You are correct to advise against the #4 &#5 switches.

    Regarding Peco switches...I've built a number of layouts utilizing the curved side or diverging side of the switch to continue the main line with the straight portion allowing access to a secondary main or siding. Unless, I split the switch because the tower man failed to align the switch correctly I've had no problems with derailments...caused by the switch points or frog. Most of the derailments have more to do with improperly gauged wheel sets or mixed wheel sets. Another topic for another time.

    Just my experience talking based on the school of hard knocks. Sigh!
  16. Triplex

    Triplex TrainBoard Member

    Peco switch geometry may be unprototypical for most situations, but then our turnouts are usually sharper than the real thing anyway, like our curves. The smooth continuous curve will operate well, except in crossovers. There, conventional straight-frog turnouts have an advantage: they reduce the S-curve.

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