[PRCo] Re: Derail

[Phillip Clark Campbell]

My name is Phil isn't it.


----- Original Message ----
From: "fwschneider at comcast.net" <fwschneider at comcast.net>
To: pittsburgh-railways at dementia.org
Sent: Thursday, September 27, 2007 1:49:10 PM
Subject: [PRCo] Re: Derail

Ah, but some, like the one on Fineview were simply sprung to restore to the derail position after the car went through it.   Such derails were used to prevent cars from rolling backwards.
I thought the one at Tunnel was a timed derail using two contactors but Herb appears to have corrected that false impression.
-------------- Original message -------------- 
From: "Boris Cefer" <westinghouse at iol.cz> 

> Yes, Fineview had a derail on Carrie Way. An another derail that "I 
> remember" was on 5-Spring Hill near the foot of Itin Street. 
> Thanks for the description! I haven't heard it yet. 
> 
> Boris 
> 
> ----- Original Message ----- 
> From: "Phillip Clark Campbell" 
> To: 
> Sent: Wednesday, September 26, 2007 9:10 PM 
> Subject: [PRCo] Re: Derail 
> 
> 
> > The derail worked similarly to any track switch in that it was controlled 
> > by the operator through a contactor in the overhead. For Prc it was 
> > coast through the contactor to set/maintain the straight through or draw 
> > current through the contactor to set/maintain a diverge movement at 
> > turnouts on the system. 
> > 
> > The Derail was a special situation - it was a diverge movement to derail 
> > and a straight through movement into the tunnel when set properly but it 
> > was necessary to draw current through the contactor to set for this 
> > straight through movement. This was a spot for crew changes wasn't it 
> > and if a car rolled when the operator was not present it would coast under 
> > the contactor and not set the point to travel into the tunnel - the car 
> > would technically derail but there was a block there to prevent this and 
> > stop the car instead. 
> > 
> > On the old cars the operator could use a combination of power and brake 
> > simultaneously to draw the current through the contactor; on Prc Pccs 
> > there was a toggle on the dash which drew current through a resistor to 
> > set points for diverge. It was forbidden on Prc Pccs to set points by 
> > using the power pedal. Thus the operator had to take specific action to 
> > set the point straight at the derail. 
> > 
> > The derail had a time delay feature as well -- the track point would not 
> > set immediately upon passage through the contactor. This could possibly 
> > catch a car with slack brakes. 
> > 
> > After the car passes through the derail successfully there is a simple 
> > contactor in the overhead (like those used to activate Nachod signals) 
> > that resets the point for the derail position. It doesn't matter if the 
> > car coasts or draws power through this contactor. 
> > 
> > This junction and derail were interlocked with outbound movements.. If a 
> > 44 or 48 car had already set its point and proceeded through the turnout 
> > it prevented operation of the interurban derail until the 44 car cleared. 
> > 
> > As originally built the derail was a RR point and possibly operated by the 
> > man in the tower -- but this would not catch equipment with slack brakes 
> > would it. Don't remember when Prc first used electric turnouts; believe 
> > it was in the 1920s but don't have my notes. 
> > 
> > I have often wondered why there weren't derails in the outbound tracks as 
> > well since crew changes happened in this direction; a car could roll 
> > backward into the tunnel. Such a derail is a simple sprung point. 
> > 
> > Prc had derails at other locations and some reverse derails for cars that 
> > would roll backward. There were derails on the 46 aka 49 on New Arlington 
> > but being single track they have to be for rollbacks in one direction. 
> > Didn't the 21 Fineview also have derails to prevent rollbacks? 
> > 
> > Phil 
> 
> 







      ____________________________________________________________________________________
Tonight's top picks. What will you watch tonight? Preview the hottest shows on Yahoo! TV.
http://tv.yahoo..com/