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Radius curve mixing

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  • Member since
    April 2007
  • 5 posts
Radius curve mixing
Posted by Roger on Monday, June 22, 2009 12:38 PM

Will mixing atlas radius curve snap track cause derailment problems?  For instance you may have a few 18" Radius snap track and then change to add a few a 15's  or 22's in the same run.

 

Thanks,

Roger

 

 

  • Member since
    November 2002
  • From: Colorado
  • 4,075 posts
Posted by fwright on Monday, June 22, 2009 12:59 PM

No, mixing by itself will not cause derailments.  In fact, if you put the widest radius curves closest to the straight, you get a quasi-easement, which will help a little with tracking through the sharper curves.

If you are mixing the radii to get an in between radius such as 20", it's usually easier to just use flex track to get a more consistent curve.

The real issue is whether your equipment will track through the sharpest radius in the series.  If you have a full piece of 15" radius somewhere in the curve, only shorter cars and locomotives are going to stay on the track.  Almost no North American prototype passenger cars (Overton and the shorter 19th Century models being the exception) will go around 15" radius curves.  Full size passenger cars usually require 22" radius or greater to avoid derailments.

my thoughts, your choices

Fred W

  • Member since
    May 2005
  • From: Westcentral Pennsylvania (Johnstown)
  • 1,496 posts
Posted by tgindy on Monday, June 22, 2009 1:10 PM

Flex track also makes it possible to plan for easement/tangents at the end of the radius curves and indirectly adds a smidgeon of mixing the radius to put in those tangents.  Flex track reduces soldering of many sectional track joints.

Conemaugh Road & Traction circa 1956

  • Member since
    April 2007
  • 5 posts
Posted by Roger on Tuesday, June 23, 2009 9:35 AM

Thank you. I appreciate your input. Good advice.

Roger

  • Member since
    July 2008
  • From: Ohio
  • 98 posts
Posted by NYC-Big 4 on Tuesday, June 23, 2009 10:32 PM

You may have your sense of direction already, but back in the seventies I built a layout with a double mainline using 22" radius atlas sectional track on the outside and a combination of 18" & 22" on the inside to maintain at least a 2-1/4" clearance.  I made sure, either with a dremel or file, that there were no gaps in the rails by filing the rail ends where I sectional track was joined together.  I ran Rivarossi heavywieght passenger cars often and never had opposing trains rub each other, although it was a tight clearance between an engine cab and the car overhang.  Usually all the freight was 34' and 40' cars.  As far as derailments, none that spoiled any operating session or that I attributed to using sectional track.  Any derailments I did have with a few 40' cars were eliminated when I started replacing the old horn-hook couplers with Kadee knuckle couplers.  Since that layout I have always used flex track.  Less joints and greater radii flexability.

NYC Willy

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