[PRCo] Fwd: Transit expert elaborates on conduits for Trolleys

[James B. Holland]

--- In TrolleyPolitics at yahoogroups.com, STEPHANLOU at ... wrote:

 
TAR:  Yes, it was  utilized in other places, as well. 
The big advantage was  there wasn’t an overhead wire.  You didn’t
have that ugly wire, with all  the supports to hold it up: you
didn’t have the trolleys (technically, a  “trolley” is the hunk
of metal at the end of the trolley pole with a big U-shape  slot where
the wire fits in â€" and, one hopes, stays) constantly coming off the
 wire and having to be replaced on the wire by the motorman getting
out of the  vehicle and pulling on the wire; … 
TAR2:   OPPS!!!! 
I SHOULD HAVE SAID, “…  pulling on the ROPE.”  The overhead
catenary wires were HOT and touching  them, particularly while in
contact with anything that could serve as a ground,  would be very
likely to result in the lost of employment â€" and  life. 
The trolley poles were  generally made of wood and a rope that was
attached near the top, just under  where the trolley proper make
contact with the overhead wire, with the other end  of the rope
attached to the back of the vehicle, with a few feet of slack.   The
poles were spring-mounted to flex upward, putting pressure against the
wire  sufficient to keep them there, but not sufficient to create too
much friction,  wear, or bounce. 
When the trolley came  off the wire â€" which happened both by
accident and when smart-alec kids thought  it was funny â€" the
operator would get out of the vehicle, come around the back,  and pull
on the rope to get the trolley back on the  wire. 
Sorry, I didn’t notice  this idiotic misstatement until I saw it
when it came  back. 
END  TAR … you didn’t have the  risks of wires breaking, meaning
having a bare metal wire with somewhere in the  neighborhood of 750v
DC and one hell of lot of amps flopping around hitting who  knows
what; etc. 
The big disadvantaged  is that it had to be designed, and maintained,
to be VERY safe â€" you are talking  about your main electrical
contact supplying the juice, instead of being way up  in the air where
it is difficult (not certainly not impossible) for people to  touch it
(how would you like to be a fireman responding to a call on a street 
with overhead wires?), it now down at ground level where any idiot can
stick  something in there and make contact.  So, the fun part was
designing a shoe  or paddle, or whatever these particular types of
contacts were called, that fits  through a long, narrow slot running
down the middle of the right-of-way where it  would make pretty darn
continuous contact with the go-juice wire, including when  it was
turning corners, going over crowns in roads, etc.  Now, keep in  mind,
this is a street, and there are all kinds of things that are
constantly  hitting this device, jarring it, etc., and you can’t let
it come in contact with  anything that conducts electricity, or
you’ve got big, BIG  trouble. 
Keep in mind that bad  things happen when you put metal things powered
by electricity outside.  I  am aware of fairly recent cases where
people were electrocuted in a bus shelter  that electric lights that
shorted out and where people came in contact with  street furniture
that shorted out. My understanding is  that such contacts were usually
between the two running rails.  Well,  obviously, this sorta restricts
the use of ties.  There are ways to get  rails to be placed so they
will stay in alignment and the same distance apart  without ties, and
if you are doing this in a street where there will be auto’s  (and,
in the day, horse-drawn vehicles), this was the norm, even then, but,
if  you are running an alignment where you are in a separate
right-of-way, on dirt,  not in a street, then putting down rail
without ties was another matter.   Of course, in such an operating
environment, the advantages of not having the  overhead catenary were
generally less important, so my understanding is that it  was not at
all uncommon for cars to be equipped with both types of power 
pick-ups so they could be used on all the routes, or even on a route
that might  switch from one way to the other in the middle of the
route (I do not know if  such routes existed). 
I don’t for sure, but  I’d guess that the overhead catenary would
be less  expensive. 
Tom  Rubin



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