[PRCo] Re: Stumped

[Herb Brannon]

The signals at each end of the single track have two positions, red and yellow. These signals indicate the status of the single track block. There is also a small yellow indicator signal about a car length from the two position signal. This signal "blinks" each time a car enters the single track. The "blink" is displayed at both ends of the single track block. 
   
  When coming off the double track into the single track an operator will know the situation on that section of single track by observing the first, or the two position signal. If it is dark then the single track in not occupied by either leading or opposing cars. In fact, both the two position signals at either entrance to single track will be dark. If the two position signal is showing yellow this indicates one or more Leading cars are in the single track. If the two position signal shows red this indicates one or more Opposing cars are in the single track.
   
  The Preliminary Contactor actually sets the signals for that particular single track block into motion. If a dark signal is noted an operator knows to pass under the Preliminary Contactor and proceed to the Counting-In Contactor. If a red signal is noted then an operator knows to pass under the Preliminary Contactor (to get his car "noted" in the block) but to then stop short of the Countng-In Contactor. If a yellow signal is noted an operator knows to pass under the Preliminary Contactor and also pass under the Counting-In Contactor, entering the single track, however, to run the car under caution as there are one or more Leading cars in the single track. These leading cars may be stopped for any number of reasons and there is no signal protection.
   
  Operators, myself also, who approached a dark signal but then had it turn red before passing under the Preliminary Contactor then knew that one or more opposing cars were coming down the single. By watching the small yellow "Counting-In Signal" located just where the double track ends and by counting the number of "blinks" could (with knowledge of the running time in that single track section) estimate how much time would be required to clear the single track for them to move forward.
   
  That, Professor Holland, is the very wordy explanation of how that Machine Age system works. Hopefully I did not leave anything out.
   
  
Jim Holland <PRCoPCC at P-R-Co.com> wrote:
  Thanks Herb!

What happened after passing the first Preliminary Contactor?




Herb Brannon wrote:

> >From the Signal Manual (1973 PATransit edition -- same as PRCo except 
> for signal drawings rather than photos) :
>
> "At each end of the single track three contactors are installed on the 
> trolley wire for the actuation of the signals as follows:
>
> (a) Two contactors are mounted on the trolley wire over the track by 
> which cars enter the single track block. The first of theses 
> contactors engaged as the car approaches single track is known as the 
> Preliminary Contactor, and the second one, which is mounted about a 
> car length beyond the first, is known as the Counting-In Contactor.
>
> (b) One contactor is mounted on the trolley wire over the track by 
> which cars leave the single track block and it is known as the 
> Counting-Out Contactor."


Herb Brannon