Position Light signalling
    NW Mailing List 
    nw-mailing-list at nwhs.org
       
    Thu Mar  8 20:07:21 EST 2012
    
    
  
The leading point of a turnout, 3 light position, color position, or 
color light or semaphore generally will have 2 heads 1 over the other, 
not 2 masts.
For the reverse direction, you have 2 tracks to control.
so you have 2 signals, one on the right track, one for the left.
You would have a single mast for the main, and a single mast for the 
diverging route.
However, certain terrain conditions, or economic conditions may allow or 
make placing the signals on one mast with a split mast which may be 
placed on the far right side of both tracks.
The right signal governed the right track, the left signal governed the 
left track.
Now consider the C&NW which had signals on the left side, well, they 
were left hand running.
-Lynn-
Subject:
Re: Position Light signalling
From:
NW Mailing List <nw-mailing-list at nwhs.org>
Date:
3/7/2012 12:06 PM
To:
nw-mailing-list at nwhs.org
   Some two masted signals supported on a single Y shaped post I though 
indicated where a single road split into two routes, but on further 
study these are positioned where no such split occurs. I also thought 
that signals were sighted to the right (Engineer's side) but again not 
always does this hold true, although those on cantilevered brackets seem 
to help in this way. Can anyone point me in the right direction on these 
matters?
Rule 337 from N&W Rules & Regulation effective 11/18/1951 - *"Signals 
are located over or at the*
*right of the track they govern, unless otherwise provided."* The "Y" 
shaped post supporting the
two signal masts was identified as a bracket. As a rule, on the 
Shenandoah and parts of the Radford
Division, the mast governing main track movement was taller than the 
mast governing movement from
the leaving end of the siding.  Where there are bracket signals 
governing movement in either direction
on two main tracks, the brackets are of equal height  . Where two main 
tracks converge into one, the
bracket signal would be at the leaving end of the two main tracks, not 
at the entering end.
     I also see that the heads themselves usually only have lights for a 
limited number of indications to suit each individual case, the 
remainder of the positions having blanking plates.
Until _about_ 1960, most aspects were displayed by three amber (yellow ? 
whatever!) lights in various
positions (vertical, horizontal, or diagonal) on each signal target 
(a.k.a. head). As color position
lights came into play, there was no need for the center light because 
CPL's required but two lights
per head to conform to the signal aspect.  The center hole was then 
plugged with a plate.
                                                                                     Harry Bundy
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