Block Indicators

[nw-mailing-list at nwhs.org]

I saw only two types of "block indicators" in use on the N&W.  (And here I am 
speaking of applications in stations, yard offices, switchmen's shanties, 
etc.)

The first type was purely electrical... a sheet metal box with a lamp inside 
and a "jewel" (green or red) on the front. Usually "lamp lit" indicated the 
block was not occupied, and "lamp extinguished" indicated the block was occupied 
by a train.  I remember seeing these at Payne, at Park Street Roanoke, and a 
few other places.

The second type of block indicator was electro mechanical.  On the outside, 
these indicators consisted of a rounded-top sheet metal housing about 8" high, 
fitted with a semi-circular glass window on the front, of about 3 1/2" 
diameter.  Inside was a pair of magnet coils, an armature and a linkage to turn the 
sheet metal disc on its center spindle.  Half of the circular rotating sheet 
metal disc was painted red, and the other half white.  If the track circuit were 
unoccupied, the magnet was energized and the white portion of the rotating 
disc showed behind the glass window.  If the track circuit were occupied, the 
magnet coils were de-energized and, by gravity, the disc rotated and the red 
portion showed behind the glass window.  I distinctly recall seeing this type of 
block indicator at Salem and Bassett.

I have to guess at the dimensions of the second type indicator (the electro 
mechanical type) mentioned above, but can firnish good dimensions on the first 
type.  They were 4 3/4" high,  and 3 1/4" deep.  A single indicator measured 3 
1/8" wide, and a double one measured 4 3/4" wide.  The glass "jewels" are 1" 
diameter.  These were not thrown-together quickie jobs, but were probably made 
by Union Switch & Signal Co, and all edges which were not bent on a metal 
break were neatly welded and then dressed down.  The lamp sockets were two-pin 
bayonet with single contact base, and of the same size as a standard 12v 
automotive tail lamp.

So my question is...  Does anyone have access to one of the old "electro 
mechanical" type block indicators (the type with magnet coils and rotating disc)?  
I'd like to get some dimensions and maybe a photograph or two, so I can build 
one.

-- abram burnett
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://six.pairlist.net/pipermail/nw-mailing-list/attachments/20050326/0ffbfe0a/attachment.html