[PRCo] Re: Pittsburgh Overhead

[James B. Holland]

If the pantograph has any real  *Operational*  advantage over the 
trolley pole, it is just marginal at best.

Dewirements of Trolley Poles do  *Not*  Mean Damage  --  can Not Think 
Of Even One Instance where a TrolleyCar Trolley Pole dewirement caused 
damage  --  It IS possible, but It IS unusual!


A catcher works via centrifugal force and just stops the upward motion 
of the pole and since the pole is at wire height when it dewires the 
best a catcher can do is stop the pole so the Top Of The Pole is several 
feet above wire height.       There is a crescent shaped lever on the 
back of the rope take up spindle which is held in place by a spring  --  
fast outplay of the rope  --  centrifugal force with which You Are Well 
Familiar  --  causes the crescent lever to move out and engage teeth in 
the outer perimeter which then stops the upward movement.       Relaxing 
the tension on the rope and allowing the wind up spring to wind the rope 
in releases the crescent lever which is spring returned to its holding 
pattern and the rope wheel will move both in and out freely.

So the pole dewires, the catcher stops it with the top of the pole 
3-feet above wire height, the pole hits the next span which, low and 
behold, pushes the pole down which is same as taking the pressure off 
the rope and crescent lever so the wind-up spring winds rope in and 
crescent lever resets in holding pattern allowing free upward movement 
of the trolley pole again.       As the pole slides off the span it 
starts up rapidly which then activates the crescent which then stops the 
pole with the top above wire height.       Rarely does the catcher hold 
the pole below wire height.       It is possible but this is usually the 
result of the pole slamming hard against a span with a good bit of 
forward momentum to the car which then causes the trolley pole to 
descend well below wire height  --  Then the catcher can catch the pole 
below wire height and hold it there  --  the uninitiated will then say 
the pole was retrieved but This Is Not The Case.


Egg--Zample:::::::      Riding early morning 38-Mt.Lebanon Inbound with 
Isadore Reichert.       After crossing the Palm Garden Trestle we hit 
the prw which is gentle downgrade at first with very gentle right 
curve.       We then start modestly upgrade, go through a road crossing 
from the lower buildings, then into a sharper right turn with storage 
tracks of PCCs on either side.       I note a broken hanger whose ear 
has obstructed the trolley wire on this sharper turn and sure enough, 
the pole dewires.       I tell Izzy but he says:       ""Doubt the 
broken hanger; just the way the car rocks and rolls here.""       
Outbound Izzy confirms the broken hanger and calls it in but not before 
we witness a good 1601-City Car at speed 3-4 times of ours hit the 
hanger and dewire.       He traveled almost 6- car lengths modestly 
upgrade before getting the car stopped and that pole was above wire 
height and had smacked into Quite A Few Spans in the process.       NO  
damage to pole nor overhead.       Pole put back on overhead and off he 
goes.       Didn't even knock the ear loose from under the contact wire!

Dewirements like this on TrolleyCars in SF in the 1970s were Multiples 
of Times Daily  --  No wire damage.       Terrible Trolleywire here in 
SF then.       Trolley coach is a different story because the swivel 
shoe allows it to snag in something Much More Easily even though 
controlled by retrievers instead of catchers.

Believe it was pantographs causing derailments on PCCs in the Burgher 
after they were pan equipped!       Yupp    ----    you read that 
correctly.       Pans don't dewire so operators were whipping it through 
turns Much Faster than they should have causing dewirements  --  
witnessed this personally at Wash.Jct. and, sorry to say, but believe 
many of the derailments at the turning loop here was speed through the 
trailing turnout because of pantographs  --  trolley poles would force 
slower operation because the operator thought the pole would dewire  --  
with pans it is the trucks derailing.       Another case for maintaining 
the Trolley Pole :-) ;-) :-D

Trolley Pole damage is Much More Likely to occur in backing maneuvers 
although damage to poles can not be ruled out from forward movements, 
but I have never witnessed such.

Everything has its positives and negatives.       Not really worried 
about power draw with light rail so that advantage of pans is ruled 
out.       Pans fail witness your URL below and poles dewire.       
Simple to rewire a pole but not so with a pan.

I have always been Ultra Fascinated with Trolley Poles, Overhead wire, 
wheels, flanges, and track work.       I am strictly a trolley pole 
person personally and for my model work, pantograph equipped models 
Shall Not Be Allowed On The Property For Any Reason, NOT  EVEN  to set a 
pan equipped car on the tracks for pictures  --  NOT  EVEN    ----    
TROLLEY___POLE___ONLY.


Jim



Boris Cefer wrote:

> It is possibly our conservatism against the trolley poles. Without any 
> long observations, I can't make any objective comparison.
> But under certain conditions, like a pole not stopped by the catcher 
> at a proper height, the pole can cause extensive damage to both itself 
> and the overhead.
> B
>
> PS: There is nothing like a dewired pantograph. Only broken :-D)))))) 
> See the attachment.
>
>
> -- Attached file removed by Ecartis and put at URL below --
> -- Type: image/jpeg
> -- Size: 83k (85798 bytes)
> -- URL : 
> http://lists.dementia.org/files/pittsburgh-railways/Broken%20PTG.jpg