SIGNAL PROBLEMS

[Jim Holland]

Greetings!

Fred W. Schneider III wrote:

> Pittsburgh Railways Co. didn't have the same problems with Natchod signals
> actuated by trolley wire contactors, but our experience at PTM indicates a
> totally different range of problems.  Natchods are most sensitive to trolley
> pole spring tension, car speed, and the width of the wheel or shoe.  They don't
> like weak poles.  They despise cars going faster than five miles an hour through
> contactors.  Certain cars with shoes won't work consistently because our
> contactor width is designed for wheels .

	What kind of overhead contactors are used?  Is it the one that has a
leaf paralleling the trolleywire for about 2-feet on either side of the
trolley wire?  This is the type that PRCo commonly used for signals
operated from the overhead; it was used on the 38A between Clearview and
Castle Shannon.
	If this is the type it befuddles me as to why spring tension would
affect operation.  I can see speed possibly being a factor and
definitely the size of the wheel or shoe, but I don't understand the
spring tension being a problem.  Would be interesting to understand why.
	Five-mph is almost a dead stop - I believe it was rather common for
PRCo to be hitting these at 10-15-mph - but could see that going fast
might be a potential problem.
	The thing about the prototype is that it is in constant use and while
this produces wear it does keep it functioning.  With a museum operation
where there is sporadic operation the equipment can become sluggish,
even electrical equipment!  There is a parallel to an auto sitting idle
for many months - a parallel but a definite big difference in operating
characteristics after sitting that long!!
	I have seen that with some of the inductance turnouts used in the TC
overhead here.  Some turnouts are rarely used - and trying to set the
turnout for the first time in months usually does not produce results. 
It might work after several tries and then function normally after that!

	There is a picture of one of the contactors I am describing on pg.19 of
Harold A. Smith's book *Touring Pgh. by Trolley* - upper right - and I
see at least 2-more in that photo!!  Also the picture on pg.22 we are
looking up under one of those contactors; also pg.42 - pg.18; pg.71
center photo 2-contactors; should be some on pg.43 but they are not
discernible.
	These signal operating contactors are distinctly different from the
contactor used to throw a track switch as top photo pg.8 and the trolley
pole of 1797 is ready to cross the contactor for the turnout; pg.12 top
photo; pg.55 top left; pg.77 top photo; pg.79 the trolley pole has just
crossed the turnout contactor.

	From Volkmer's color book of the Pgh region, the signal operating
contactors are on pg.72 top; pg.83 top; pg.105 bottom; pg.108 bottom;
pg.113 top.

	From Volkmer's color book of the Pgh region, the track switch
contactors are on pg.96 bottom; pg.124 bottom; pg.49 JTC top right.

	There was another style of contactor for signal operation that I saw
only on the Drake to activate a safety stop near a school crossing south
of Santa Barbara siding near Hultz (Bethel Village).  There were
2-contactors - one on either side of the grade crossing and these
contactors were directional sensitive since this was a single overhead
wire, not gauntlet as on Overbrook parallel to Saw Mill Run Blvd.
	The contactor had a casing that was rounded on top and straight on the
sides which paralleled the overhead on either side of it for about
2-feet.  Within this casing were two moving contactors placed at an
angle to the trolley wire and on either side of the wire.  Approaching
the contactor heading south, the contactor on the right side of the
trolleywire was touching it and angled away from the wire.  The
contactor on the left side was away from the wire but angled in to touch
the wire on the south side.
	As a trolley pole wheel entered the contactor southbound, it would
actually ride on both the overhead and the right side contactor and
would pull this right side contactor in against the wire as it
proceeded.  It would just scrape against the contactor on the left side
as it exited.  Pressing this right side contactor is like depressing a
key on your keyboard to activate an electrical circuit and it is spring
returned to its former position.
	This then activated a way side signal (Nachod?) that was time delayed
to force the interurban to make a safety stop.
	Approaching the second contactor heading northbound and the left side
contactor becomes the right side contactor - the two sides are mirror
images of each other - and the time delayed safety stop signal was
activated.  Going thru the second contactor on the far side of the of
the grade crossing would not activate anything unless it was a recording
device to record the time between activating the first and second
contactor to make sure the safety stop was made!

	Wouldn't it be fun to try to model something like that!  I have
operated my turnouts using trolleywire contactors but it tisn't easy to
do!

	Interesting that Ohio Brass apparently did not make these items for
trolleycars - nothing in their 1948 catalog.

James B. Holland

        Pittsburgh  Railways  Company  (PRCo),   1930  --  1950
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