"Basic" Question on Diverging Turnout Track...........

[mobilman44]

Hi!

I'm doing layout design and working primarily with Atlas # 8 and # 6 HO turnouts for main and submain trackage.  I'm trying to determine - for want of a better word - the radius of the diverging leg of these turnouts.  My reason for wanting this information is, for example, "if a given passenger car will operate on a minimum of 24 inch radius track, what is the equivalent turnout number that would relate to that radius?"  

I confess I used to know how to determine this, but between old age and a plethora of Ebay stuff, I have forgotten..........

Thank you,

Mobilman44 

[selector]

N. American style turnouts don't have a radius...only from the point where the points start to thicken to full head witdth and on to the end of the closure point where they meet the frog and turn magically into wing guards that run parallel to the frog points.  On the other hand, snap style, and the earlier Peco and European turnouts often are curved through out, including past the frog.  So, the Atlas #8, unless they make such a beast in snap track, will be the kind that becomes tangential at the frog and on until the turnout proper ends.

If you look in the NMRA specs for HO turnouts, you'll find a column for "substitution radius".  I'll leave it for more savvy folks to tell you what good that info really is, but is does not mean you can slip N. American standard config turnouts into a curve of a defined radius and have them become part of the curve.

[tomikawaTT]

Turnout specifications include two radii - substitution radius and closure radius.  With commercial turnouts, substitution radius is rather meaningless since it assumes that two points on the curve are at the tip of the points and just beyond the frog wing rail ends.  (The extra straight rail of the diverging route fouls up the equation.)

The radius you are concerned with is the closure radius - the radius between the heel end of the point and the frog.  That's the one which will dump you 2-10-4 or pedestal tender on the ground.  IIRC, a #5 turnout has a closure radius of 24"  The higher the frog number, the greater the radius.

Chuck (Modeling Central Japan in September, 1964)

[rrinker]

#4 RCR: 15", R Subst: 29"

#4.5 (Custom-Line #4) RCR: 22"  R Subst: 36"

#5 RCR: 26", R Subst: 44"

#6 RCR: 43", R Subst: 56"

#8 RCR: 67", R Subst: 110"

For HO. N about half that. This is why John Armstrong said for most layouts, anything bigger than a #6 was just a space waster. Pretty much any model can ge tthrough the 43" closure rail radius of a #6. #5 is a good compromise unless you run large steam, medium and small locos can handle 26"

                         --Randy

 

[mobilman44]

Hi,

Well I think you all answered my question, in that an Atlas # 6 would handle most anything, but a number 8 is much better.  I know that there is no radius per se attached to the Atlas turnouts, but obviously there is a change in direction that larger cars/locos could have a problem with on the smaller number turnouts.  

Yes, I do have an NMRA gauge (actually 3 of them - been a member for decades), and I learned long ago to gauge & file points, etc. on the Atlas turnouts before installation. 

The layout design I'm working on calls for 9 (or 11) # 8s, which are used on the main and on the passenger train storage/staging tracks.  The "sub mains" or secondary trackage is assigned # 6s, and industry and yard trackage are # 4s.  Lead in tracks to the engine terminal will be # 6s.

Thanks to all of you - I appreciate your input!

Mobilman44

[tomikawaTT]

The joker in the passenger-trackage deck is the need to avoid S-curve problems when running through crossovers and the first track off the ladder.  A #6 switch gives a 2-inch offset in 12 inches, but part of that is eaten up by the curving closure rails at each end.  With a #8 crossover, the straight rail is almost exactly as long as that 85 foot Pullman - which is what the gurus tell us we should have to avoid problems.  Hence #8 turnouts on mainlines, in passenger stations and in coach yards are really the best way to fly.  (That includes single and double slip switches, if you use them.)

Chuck (Modeling Central Japan in September, 1964)

[rrinker]

Either a full car length, or as short as possible. I had no trouble with 85' cars with body-mounted couplers running warp speed through the normally freight only Atlas #4's (really 4.5) in my yard. In fact that was the final test - if a GG1 could pull and push full-length cars through the trackwork running nearly wide open (at full throttle I think it would have rolled Lionel-style), then I considered it plenty good enough. Good metal wheels, in gauge, and enough care taken with installing each turnout so as not to create a kink, and it all ran great. I don;t think I did anything special, nor did I alter the turnouts in any way after removing them from the package. I also didn;t work SO slowly tha tit took days to put down a couple feet of track. Kinda makes me wonder about some of these layouts where trains constantly derail. Only 'problems' I ever had were always traced to wheels being out of gauge when checked. Replaced the troublemakers with quality metal wheels and never a problem again.

                       --Randy

 

[rrinker]

 I never touched a thing on any of mine. EVERY car that bumped through the frog or derailed was shown to have out of gauge wheels. Every single time. Now, finescale wheels, and maybe even the semiscale wheels, are not going to work, but I had zero issues with standard RP-25 wheels so long as they were actually in gauge.

                                           --Randy

 

[jrbernier]

David,

  I'll go with Randy on this one.  I have 43 Atlas code 100 Custom Line turnouts on my layout.  Only 'one' had a 'defect' issue.  Sometimes the metal frog is too high(I suspect that pulling it from the hot plactic mold may be the culprirt.  In one of those 'Saturday Night' brain storms, I used an 'iron' ssitting on the rails to 'sink' the frog back down to level with the rails!

  I have cleaned up the 'points' as others have mentioned, but that is not just an Atlas problem.  If you lay the trackage 'flat', and have good tracking wheel sets - Good Operation!

Jim Bernier

[mobilman44]

Good Morning!

  I'm pretty much a perfectionist when it comes to track laying, and have used Atlas code 100 components (flex track and their higher end turnouts) since the '70s.  I've done a lot of reading and layout experimentation on the subject and a true believer in doing it right (or not at all). 

The existing layout has had minimal derailments - and none that I can recall - since installing Intermountail wheelsets last year.  Actually, this 14 year old layout has taught me a lot, and the new one will not only incorporate the "good stuff", but will not have the 3 major design errors I made either.

Ha, what were those errors you ask..........

1. Four turnouts were located under mountain scenery and relatively unaccessable - or visable.

2. There is a good looking reverse loop about 6 inches above the main level.  It has some nice retaining walls and rockwork, but it takes up a whole lot of space - much more than its worth.  

3. The underlayout staging area is reached by a 2 percent grade, which is really smooth, but does not lower the staging area enough under the main level to allow good access or viewing.  The new layout design calls for 2 1/2 percent, which should make a nice difference.

4. A "runner up" error was the initial painting of the rockwork ended up being too dark.  I ignored the advice about using lighter shades as you can always darken later if needed.

Anyway,

Thanks all, and ENJOY !!!!!

Mobilman44