(erielack) Re: EL Mail List Digest V3 #2885

[dawest1701_@_aol.com]

Superelevation is introduced into curved track a the spiral. At what is called the TS (Tangent to Spiral) the elevation and curvature are zero. They are both introduced at a constant rate until the SC (Spiral to Curve) point at which both the elevation and curvature are at their maximums for that curve. This is also called the "Full Body". The inside or low rail is often called the grade rail. The elevation is introduced by jacking up the outer rail, and then tamping the track. Lowering the inner rail would require the track to be undercut, and no one is going to do that. To get EL content the EL General Track Work Standards states, "The super-elevation at any point on a spiral shall be sufficient to conform to the super-elevation tables for the ordinate at that point." So if you have a 4 degree curve with 4" of superelevation (which according to the EL book is good for 45 MPH); the halfway point of the spiral should?be a 2 degree curve with 2" of elevation. In the table that combination is good for 50?MPH;?so we meet EL standards.

In the picture both tracks are elevated, and are set as presented, i.e. in one plane. Another catch to curved turnouts is that the lead distance must be modified when they are placed in curves - one is shortened and one lengthened..

DAW






Date: Wed, 01 Oct 2008 20:52:52 -0400
From: "Schuyler Larrabee" <schuyler.larrabee_@_verizon.net>
Subject: RE: RE: (erielack) Superelevated curves on model railroads (w

http://lists.railfan.net/listthumb.cgi?erielack-10-01-08 

> Attached is a photo of the prototype. Note the track the train is on is
> "canted"." This image is from an earlier period than I'm modeling - in my
> timeframe, the left-most track is gone. The curved crossover is in the
> immediate foreground - the switch at left foreground is the west end of the
> crossover, and the east end is immediately behind the photographer. The cant
> of the track implies it's superelevated, no?
> 
>   - Paul

I don't read the photograph that way.  I agree that the track with the Phoebe on 
it is
superelevated, that's hard to miss.  But to my eyes, the other two tracks to the 
left are not
superelevated at all.  They appear to be flat (level too, but in terms of 
superelevation, flat) to
me.

Some of the track on the Club layout that I built is at . . . . wait for it . . 
.  Schuyler
Junction.  It involves no less than three curved crossovers.  The inside radius 
of the three lines
is 36"+.  The centers are 2.5", which is USUALLY enough for clearance against 
opposing moves.  My
advice would be to find a way to either use larger radiuses than that (much 
larger) or to abandon
all hope ye who en . . . no, that's something else . . .abandon all hope of 
modeling that as you see
it there, UNLESS any moves to the inside track will be Very Low Speed moves.  I 
just checked, and
while I have many photos taken to show track configuration around the rest of 
the layout, I have
none of SJ.  I'll fix that Thursday night, Club night.

These curved turnouts have also required an inordinate amount of maintenance, 
first because they're
on spline (major mistake, should have been on a solid block of basswood), and 
therefore the earth
moves (did it move for you too?  DARN, I keep getting off topic here . .) and 
therefore the rails
move, and tend to get out of gauge.  Second r
eason is, I think, because trains 
stress these more
than the conventional x-overs we have elsewhere.  And because the points are 
necessarily very long,
and that just increases the need-to-stay-in-close-adjustment factor.

SGL







	The Erie Lackawanna Mailing List
	http://EL-List.railfan.net/
	To Unsubscribe: http://Lists.Railfan.net/erielackunsub.html

------------------------------