[PRCo] Re: Power Off/Switch Contactors/Overhead signs

Fri Apr 25 20:18:25 EDT 2008

Hi Mr.Cefer!

Very accurate and nice description Mr.Cefer; never heard of any welding together as the gap is too large isn't it.  'Power off' is instruction to the motorman to coast through the insulator.  I am including a scan I found somewhere on the web (hope it comes through as I have had trouble sending pictures before haven't I so I am also sending this message to Mr.Cefer asking him to repost the image if it doesn't take please) which shows 2 different styles of many offered by Ohio Brass.  The original picture from Mr.Barry shows an older style which looks similar to the one on the left of the enclosed photo doesn't it.  I vaguely remember these 'older' style in Pittsburgh but the one on the right was the standard from at least 1950 forward, possibly earlier.  The one on the left has a lower profile but bulkier as the standard wood strain insulators are used on either side parallel to the contact wire to strengthen the unit; the insulating runner piece here is
 reinforced rubber.  The renewable rubber runner piece could have been problematic during WW2 shortages and possibly led to their being replaced by those with hickory inserts.

The one on the right in the enclosure has a larger single piece hickory beam so it stands taller.  In both the 'tips' are applied to the end of the contact wire on either side and then placed into the 'end runner' and locked into place.  Remember that there is over 1,000/pounds linear tension on the overhead isn't there to keep it from sagging!

Fiber insulators have been more common with shoes as the carbon inserts do less damage don't they.  These fibers will often break and fall out of their own accord; I haven't heard of that with hickory.

The same type insulator for shoe has a longer insulator piece doesn't it since there is more of a shoe in contact with the overhead than there is with a round wheel.

Insulators are used to separate power sections for a variety of reasons and most definitely if they come from different substations but this is not always the case.  One substation can power many different sections of overhead separated by Insulators so power draw through any one section is not extreme and to prevent shutting down larger areas if there is a problem in one - wire down, tree on the overhead, other problems.  Systems which had many double end cars often had rules against both poles being on the overhead at the same time to prevent bridging an Insulator with power from different subs on each section  --  this could fry the trolley couldn't it!  Changing ends at the end of the line would rarely if ever encounter insulators and quite often the second pole was placed on the overhead before the first was removed.

Here are insulators in both tracks of the Interurban lines just south of South Hills  http://www.davesrailpix.com/pitts/htm/bvp028.htm  --  the same was done in the 44/48 line near Warrington both tracks, on the 40 possibly in that section of single track just above the yards so only one insulator is needed.  There may have been insulators in the 38/39/42 main just south of the west yard ladder and then near the bottom of the ramp for the 38/39.  There was; look hard between the two trolleys on the left and the one in the outbound track is clearly visible  http://www.davesrailpix.com/pitts/htm/wvp029.htm  Here is the one in the ramp visible near the trolley wheel  http://www.davesrailpix.com/pitts/htm/pitt609.htm  It takes some time to find these photos doesn't it!  There is probably one in the ladder lead to isolate the yard so that means one in the lead exiting to the main at Palm Garden.  There would then be one on Palm Garden Loop and where ever that
 track again joined the main.

Insulators at Washington Jct. in the latter day Library/Drake lines were just south of the turnout in the single track on Drake so only one is needed and in both tracks for Library at the Junction  http://www.davesrailpix.com/pitts/htm/bvp170.htm

There were 2 Insulators at the Dormont wye - one in the wye leg above the sidewalk and one in the connection used by the 42/38 owl in the single track over McFarland.  When the 38 line was discontinued these insulators may have been removed, certainly the one on the wye leg.

Trolleys using 5th or 6th downtown have their own power source on 5th through Oakland.  Depending upon insulator installation they could have shared South Hills power along 5th and 6th between Grant and Wood and shared power with Liberty on both streets west of Wood.  I can't remember precise locations of insulators downtown can I.

Here is one in the yard lead at Ingram  http://www.davesrailpix.com/pitts/htm/wvp031.htm

Insulator separating Penn from Liberty on 11th:  http://tinyurl.com/3ma94x

Here's a unique location for insulators:  http://www.davesrailpix.com/pitts/htm/bvp023.htm  The one on the tangent looks like the old style while the one in the turn for the 22 is the newer hickory style.

Switch Pans:

These are old style switch pans used by PRC:  http://tinyurl.com/3cdbrf  Both operate the turnout around the admin building.  They are placed far enough back so the longest car has room to stop in case the point doesn't set properly.  This turnout is too close to the junction with the Interurbans to use only one contactor.   http://www.davesrailpix.com/pitts/htm/bvp145.htm  --  modern switch pans in the same identical location.  The modern pans came into use about 1950 and later; most if not all of the older style were gone by the mid 1950s.

Overhead Signs

Car Stop signs and others were to alert both operators and the public weren't they.  Power off, NC. track# in yards and other signs were strictly for the operators.  Not all signs were precisely where the car would stop as they depended upon span availability.  Where 2nd, 3rd or 4th were used additional spans in a form similar to strain relief were sometimes installed so they could be more precise.  Some systems required operators to stop a second time if they were the 3rd or 4th car back;  sometimes this rule was canceled during rush hours to keep more cars moving wasn't it.  http://www.davesrailpix.com/pitts/htm/jfp031.htm  traffic may have allowed for this car to open its doors before the actual sign.  http://www.davesrailpix.com/pitts/htm/jfp137.htm  doors open well before the sign here aren't they.  Three lines passed the following location:  Interurban, East/West and Jefferson/Maiden:  http://www.davesrailpix.com/pitts/htm/pitt141.htm  Normally the
 car would stop after setting the admin turnout as the first car stop is quite far down in this photo:  http://www.davesrailpix.com/pitts/htm/bvp017.htm

Power off signs were on the same span as the insulator but the motorman was almost 45-feet beyond the same when the trolley wheel passed through it so he had to guess its location for releasing the power.  They weren't always successful and there was a lurch as the power dropped and then reapplied.

Using the overhead for such signs is highly efficient as only fading with time is the enemy.  Curbside poles are subject to obliteration by delivery trucks etc as well as graffiti. 

Phil

----- Original Message ----
> From: Boris Cefer <westinghouse at iol.cz>
> To: pittsburgh-railways at dementia.org
> Sent: Friday, April 25, 2008 11:30:33 AM
> Subject: [PRCo] Re: Power Off
> 
> They would not weld together but frequent passing with power on through the 
> insulator would soon burn off the insulating part (wood, fibre) of the 
> insulator and the metal (brass) parts would become excessively rough from 
> the arcs.
> 30 amps is still OK but full PCC acceleration - roughly 500 amps with peaks 
> around 600 amps - is not OK.
> 
> B
> 
> ----- Original Message ----- 
> From: "Fred Schneider" 
> To: 
> Sent: Friday, April 25, 2008 8:11 PM
> Subject: [PRCo] Re: Power Off
> 
> 
>   But hopefully you can prevent maximum load and an idiot
> motorman will not notch up the car under the insulator and weld the
> the two ends together. 

http://tinyurl.com/3zxv5n

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