[PRCo] Re: Real Tales--No. 1/Unscheduled Meet

[DF Cramer]

My experiences working with Nachod contactors at PTM show that they work the 
vast majority of the time but they can easily miscount a car in or out, thus 
leaving an incorrect signal.  Speed and pulling power while going through a 
contactor tend to determine the reliability.  A worn contactor or a worn 
trolley wheel can also be the culprit.
Basic operation is:
On approach a dark signal is a clear track ahead.  When you go through the 
contactor the signal should change to amber, thus counting your car into the 
block.  At the same moment a red signal appears at the other end of the 
block.

On approach an amber signal tells you there is a car in front of you and the 
red signal at the other end blinks to count you in.

When you exit the block, providing you are the only car, the signals should 
go dark.  If another car is behind you, the signal will not go dark until he 
has counted out.

In theory, the system should be able to handle as many cars as can safely 
fit into one block.  Count 10 cars in, count 10 cars out.  Direction of 
travel through a Nachod does not make a difference.

In real life, the contactors need to be maintained and the operator needs to 
know his car and how the different contactors react to the different poles 
on his car.

There are all sorts of little tricks to reset the signals without getting 
into the box.  You can glide under as your conductor pulls your pole off the 
wire to not count you in will sometimes help.  The other way is to sometimes 
put up both poles and go through.

We have great overhead at PTM and he guys work hard to keep everything up to 
snuff, but the Nachods sometimes do not want to cooperate.  Part of our 
problem is we use both sliders and trolley wheels.

Any questions?


Dennis F. Cramer
Purchase College Conservatory of Music
State University of New York