I have exhausted all the options I have and hope that someone here has the info I need. I am working on an sw9 with 6SL brakes that at one point had a dead man foot pedal. It was removed years ago. There is a P-2-A penalty valve that is still plumbed into the system. That valve has been swapped out with all the other valves on regular recert intervals. Recently, there has been issues getting that side of the system to work properly. The part of that system that is supposed to remain charged and keep the contacts closed for the gen field is not getting any air. None of my brake books or locomotive books show this type of system. Does anybody have any diagrams or literature covering this system?

I have a 6SL book that might be what you need. It shows a "timing valve" that includes contacts that cut the power circuit. Shoot me an email and I will copy the applicable sections for you.

Howard

Attached PDF is a schematic of former Reading Company SW1001 with #6N distributing valve and P2A Application Valve.

We have had issues like this in the past when the wrong H5 relayair valve is installed or if a double check valve hangs up.

EBL

I sounds like your more likely having problems with the PCS (Power Control Switch) or the associated double check valve. The switch itself is basically a well pressuretrol and they do fail after a few decades.

Don't we all, Paul......

As of now I think I have found the info I need. I will be going out to check the unit next week. Based on the info that Allen Stanley forwarded to me, it looks like I may have a switch issue and not an air system issue. Once I was able to read up on exactly how the P2A valve works it started making more sense. I will post a response when I have it figured out.

Thank you all
E

According to my WABCo 6-SL book (1953), there can be a "timing valve", which is associated with ATS penalty brake applications. It shows the PCS as being connected to pipe connection #14 in the N-1-A brake application valve; the foot valve is shown connected to pipe #12 of the N-1-A; and shows no P-2-A brake application valve (the diagram also shows no double check valves).

So it sounds like your SW-9 system might have been modified by the owner. What kind of automatic brake valve does it have?

I actually talked to an ex GTW supervisor who was around when this particular engine was on the roster. He not only confirmed that it was modified, but gave me the name of the individual who was notorious for authorizing many of the "home brew" mods to the GTW fleet.

UPDATE:
Problem solved. As suspected, the problem was in the field cutout switch. Once I was able to read up on the operation of the P-2-A valve and the other components related to its operation, it was an easy fix. As suspected, this system was added on by the GTW at some point, but never documented in the records.
Thanks all for the help.
E

Your situation sounds quite complex. From what you've mentioned, it seems the field cutout switch was indeed the issue. Kudos for diving into details of the P-2-A valve operation and finding an easy fix! That's a great investigative job, especially given it's an undocumented modification. Keep up the good work!

Kudos to your detective skills in figuring out how the P-2-A valve works - not an easy task, especially with it being an add-on that no one bothered to document. Well done man! Keep chugging along