Atlas Code 55 Turnouts #5 vs. #7

[Scottew7]

I was wanting to build a yard with my first n scale layout. What is the difference betweetn a #5 and #7 turnout for code 55 atlas track. I one better than the other for yards or mainline? Thanks

 

[lmackattack]

the number tells us that one has a sharper diverging rail than the other.

a number 5 would be common in a yard, its intended for tight space slow speed running and only smaller locos would use them.

a number 7 is not as sharp and would be found on mainlines where larger locos are often found. it would not be considerd a high speed turnout but large locos would use them at 20-30mph


http://www.nmra.org/standards/sandrp/rp-11.html
http://www.nmra.org/standards/sandrp/rp12_7.html

hope this makes some sence

Trent

 

[Scottew7]

Thanks trent, Can i use large locos such as sd70m and 80 , dash 9 on a # five in the yard or just use all # 7's? all my loco's are large.

 

[lmackattack]

Scott...
Im an HO guy so I cant comment if that loco will work or not on a tight switch. I also dont run modern diesels so I dont know how long the wheel base is. I suspect its around 60'-70'?

But for example on my HO layout 18" radius is about the tightest you want to go with any smaller 6 axel diesel or med steam. these do go thru the sharp number 4-5 switches and 18" curves but they dont like it and will sometimes derail. becasue of this experince on my last layout. I decided that my current layout would have all number 6 switches on the main and into my 3 track yard as my 6 axel diesel (SD7, SD9 etc.) 2-8-4, 4-8-2locos often go in and out of the yard tracks.. I use number 5 in the industry where the smaller 4 axel diesels 2-8-2 ,2-8-0 locos often go into. I have good results with this. I think you would be fine with a number 6 on mainlines just as I am. this is not to say that you cant run a large 6 axel through a number 4 or 5 but its not reccomended by NMRA and may cause you more derail issues than you want?

 

[vato loco]

The Large loco will operate through them.....But look like hell going through them! If u got the room for #7's by all means use #7's!

 

[pcarrell]

Always go larger if you have the room. That being said, on steamers, blind center drivers on long wheelbase loco's will allow them to wiggle through sharper curves and turnouts. Can't help you with the "D" word loco's though. We didn't have them in the 1930's in backwoods Maine!

BTW, on the Atlas code 55 track, the 30 inch radius curve is the matching for the #5 diverging route and the 71 inch radius curve is for the #7 diverging route. They can either continue the curve or flip them and they'll bring the track to parallel with the proper spacing.

 

[nephthyr]

My rule is never go sharper than a #6 so in this case go with the #7's. N scale is small enough that you should have room for all #7's, and your big locos should handle it without any issues.