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From: "Joseph A DOT Braun" joebraun AT optonline DOT net
Date: Tue, 18 Mar 2008 15:14:55 -0500
Subject: Layout design
"ErieFrtEM033107.jpg" - application/octet-stream, 1000x750 (24bit)

Pul B: "For the benefit of modelers who may be discouraged by Joe's
statement, I repeat that this equipment will operate through #8 Xovers with
no problem whatsoever so I would alter Joe's statement to read "...at least
as long as the wheelbase of your longest car..."]

Paul B is correct. What I should have said is that what I defined as the
critical distance to achieve in a crossover on MY railroad is for the
straight section of connecting track (frog to frog) to be at least as long
as MY longest car. It is so easy to slip into making our own standards
sounds like edicts for all, even if that is not our intent.

[From: "Todd Stearns" Question. Where should one start a super-elevation?]

Todd, I fear getting too far afield here so I'd be happy to see if I could
help you out off-List to come up with what will work for you. Basically, the
spiral easement (tangent to infinite radius to declared radius) track
section coincides with the superelevation easement. If you can imagine the
point at which a circle of the declared radius would hit the tangent, the
tangent must first be moved away from the circle so there can even be an
easement. In HO most written bibles make that distance 1/2" and have the
easement itself as long as two of the longest car lengths, lets say, 24" in
HO. 12" of that rests on the tangent side of where the circle would have met
the tangent, the last 12" continues around on the other side of the
hypothetical meeting point and curves up to the declared radius.

Not meaning any of the following as a dictum for others, let me share what
has worked for me. I offer this only because a question was asked:

- All written words on superelevation seem to speak of shimming up the track
or ties. There is an option of building the superelevation and spiral
easements into the subroadbed. This is the path I chose to go, using 3/4"
ply onto risers whose angulation was algebraically worked out. I power
screwed the subroad into the risers. This presumes a benchwork structure
that can take the torque involved and not give.

- I used prototype 5" superelevation, which translates almost exactly to a
5-degree angle of pitch.

- I did not box myself in with that oft-cited (for HO) 24"/1/2" figure I
mentioned above for the spiral easement. I was all over the place. Attached
is a photo (by a friend) of a freight coming out of a 55" radius curve into
an easement that is 50" long with the 55" radius actually 2" from the
tangent. Play, play, play -- with design variables. But the photo shows the
aesthetic value of superelevation and spiral easements.

- Most treatises seem to recommend gluing the flex. There is an option of
spiking the flex down. This allows for the minute adjustments you might like
to make. "Kinks" occur in curvature just like on tangents, except you don't
notice them until you see car ends waddle back forth.

Again, all this is shared, Todd, to help you design what will work for you.
No universal standards are being offered for you or for anyone.

Joe Braun



ErieFrtEM033107.jpg

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