N&W's Use of PL-2 Position Light Signal Equipment

NW Mailing List nw-mailing-list at nwhs.org
Mon Apr 23 07:29:08 EDT 2012


The Long Island Rail Road also used US&S position lights. Of course, it
installed them while under Pennsy ownership.

Dave Phelps


In a message dated 4/23/2012 6:49:26 A.M. Eastern Daylight Time,
nw-mailing-list at nwhs.org writes:


There were only two major customers for Union Switch & Signal Company's
Position Light Signals, the N&W and the PRR.
There were three different generations of PL signal equipment: the original
PL-1 equipment which came out in the early 1920s, the PL-2 version dating
from the 1930s, and the PL-3 equipment of the 1940s and 1950s. The
difference in the three generations of equipment was the optical systems employed
in the individual lamp housings... all the signal mounting hardware
remained the same through all three generations of equipment.
The N&W was buying PL-1 equipment in the 1920s, by the 1940s had switched
to the PL-2, and never appears to have used the PL-3. The PRR, on the
other hand, widely installed the PL-1, then switched directly to the PL-3 and
never appears to have utilized the PL-2. I always wondered why the N&W
never upgraded to the latest PL-3 refinement, and why the PRR never used the
PL-2.
Recently I completed restoration of one each of the PL-1, PL-2 and PL-3
lamp housings, and mounted them vertically for display, and I think the
reason the N&W never bought PL-3 equipment has become apparent.
Using 9 volt 12 watt signal precision lamps in each, with all housings
equipped with standard amber "NoViol" ("no violet") glass, and all juiced at
5.6 volts, there are easily observed differences in the light-emitting
properties of the threee generations of equipment.
1. The PL-1 lamps system gives what was probably a respectable light in
the early 1920s - it certainly was better than the light provided by a
semaphore signal.
2. The PL-2 equipment (which was N&W's second-generation of Position
Light Signal equipment,) with its revised optical system, gives a brilliant
light, significantly better than the old PL-1, and the lens was engineered
with a horizontal band of ribbing across the middle portion of the inside of
the lens to provide a wide "spread" of light from side to side.
3. The PL-3 equipment (which appears to have been bought by only the
PRR,) has an optical system which gives an ENORMOUSLY brilliant light, a light
which indeed "burns the eyeballs," even when the lamps are burned at 40%
below rated voltage. However, the pencil-beam of light is significantly
concentrated and there is no attept to "spread" it from side to side.
Now granted these are close-up observations and do not replicate the
2,500-3,000 range expected from a working signal in the field, but I think they
answer the question why the N&W never bought the latest version of PL
signal equipment. The PL-2, with its "spread," was the perfect signal for a
railroad with significant curvature problems, and the PL-3 equipment was the
perfect signal for the PRR.
During my restorations, I photographed the optics and dead-on front views
of each version of the PL equipment while illuminated during darkness, and
as soon as I go through all the historical and technical material again,
will assemble the data, the photographs and the conclusions into a PDF, and
offer it to anyone who cares to read it.
One final test remains. The next time Mrs. Boss goes away for a few days,
I shall rent a "fog machine," fill the basement up with fog, and observe
the relative "fog penetrating" characteristics of the PL-2 vs. PL-3 equipment
!
Do the N&WHS Archives contain any material relating to tests and/or
purchases of PL-2 signal material?
-- abram burnett
///////////////////////////////////////////////////////////////////////
The wise philosopher Theocritus was asked which
animals of the forest are most to be feared.
Theocritus responded: "While in the hills are lions
and bears, yet in the city are tax collectors and
lawyers and sycophants, and the latter are much more
dangerous than the former. The beasts are
irrational. Man calculates his wrongs."
///////////////////////////////////////////////////////////////////////





________________________________________
NW-Mailing-List at nwhs.org
To change your subscription go to
http://list.nwhs.org/mailman/options/nw-mailing-list
Browse the NW-Mailing-List archives at
http://list.nwhs.org/pipermail/nw-mailing-list/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://six.pairlist.net/pipermail/nw-mailing-list/attachments/20120423/4bdbb472/attachment-0001.htm>


More information about the NW-Mailing-List mailing list