N&W Train Phone Equipment - Was: Planing Mill Question

[NW Mailing List]

Brent Greer asks:

>>> There is also some other cylindrical object / equipment on the tender
seen blocking the view of the doghouse in that photo. What is that? <<<

I think that is a toridal coil which is part of the "Train Phone" system.
Why it is not in the steel equipment box, I do not know. Perhaps it was too
large to fit. The large horizontal pipework on the top of the tender is
part of the antenna system.

This photo is the only one I have ever seen of the "inductive train phone"
system used on the Roanoke Hump.

About 1947, Union Switch & Signal began marketing a system called
the"Inductive Train Phone System." It worked on the principle of induction
and used the wire on the pole line to carry the signals between base
stations (stations and towers) and engines and cabooses.  Transmitting and
receiving between the engine and the pole line was done with some form low
amplitude magnetic radiation. All equipped locations used a telephone-type
handset with an earpiece and a mouthpiece. I never saw any evidence of its
use anywhere other than the PRR, prior to seeing this photograph. The PRR
used Inductive Train Phone extensively in its non-electrified territory
(i.e. everything west of Harrisburg.,) but the strong force fields
associated with 11,000 volt AC electrification completely destroyed the
signals when it was used "under the wire." I asked the older employees
about it and they reported it worked well. The first generation of PRR
Diesels were even equipped with it, and it remained in service until
1966-1967, when radios came around.

Attached is a photo of the manufacturer's designation plate from the
cabinet housing the equipment in "MO Tower at Cresson,Pa.  It identifies
the apparatus as "Frequency Modulated 80-144 K.C. Wayside Equipment," so
that gives you the frequence spectrum.

Somewhere I have an N&W Superintendent's Bulletin from about 1942,
outlining the way the Shaffers Crossing equipment worked, and listing the
engines equipped. I will make an effort to find that and post a scan to the
N&W List. The N&W's 1942 installation was probably an earlier form of the
late-1940s US&S "Inductive Train Phone" package. Unfortunately, I never
quizzed any of the older N&W employees who worked with it.  Nor was there
any remains of the system obvious when I hired in 1964.

abram burnett
turnip baron

===========================
Sent to You from my Telegraph Key
... better than AT&T 4G LTE
===========================

Moderator:

http://nwhs.org/mailinglist/2015/20150922.Inductive_Train_Phone_Tag_from_MO_Tower_Eqm_Case_1990s.jpg
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://pairlist6.pair.net/pipermail/nw-mailing-list/attachments/20150922/5d4bf298/attachment.html>