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 Post subject: J-36 relay valve
PostPosted: Sun Jul 02, 2017 11:49 am 

Joined: Sun Aug 22, 2004 9:54 am
Posts: 794
Location: NJ
I'm doing some preliminary work on an ABDW passenger car air brake system conversion project. I have access to several relay valve cores, marked "J-36" but so far have not found any information online, including Wabtec O&Ms. Anyone have any idea where I can find that information? I believe the 3 and 6 would indicate 30 and 60 percent; hopefully one of those proportions would be suitable for use with an 18 inch cylinder.

Also, can anyone recommend a source of reasonably priced ABDW cores, pipe brackets and the two chamber freight car reservoir? Scrappers?


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 Post subject: Re: J-36 relay valve
PostPosted: Mon Jul 03, 2017 12:16 pm 

Joined: Sat Jan 22, 2005 1:02 pm
Posts: 76
Location: Mi
EDM wrote:
Also, can anyone recommend a source of reasonably priced ABDW cores, pipe brackets and the two chamber freight car reservoir? Scrappers?


What do you consider reasonable?


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 Post subject: Re: J-36 relay valve
PostPosted: Mon Jul 03, 2017 7:28 pm 

Joined: Sun Aug 22, 2004 1:18 am
Posts: 109
Location: B'more MD
It seems to me that you are describing a J-style relay putting out 36% of the input pressure it sees from the brake valve via the #16 pipe. For instance, J-36 would be ideal for converting a D-22 car from iron to composition brake shoes, by replacing a F-6 relay which would be putting out 60% of the pressure signal it is receiving from the brake valve. It would certainly save the cost of sleeves in the brake cylinder(s). To move to composition shoes which are 1.6 times as efficient as iron shoes, you need to reduce brake cylinder pressure another 60%, beyond what it was, which works out to be 60% of 60% or 36%. You probably needs a filler piece and with an in-shot valve, besides. I should think it would work with an ABDW brake system as well. Just do some tests first to know you are ending up with the pressures you are supposed to. Too many people and some pretty well known organizations have switched brake valves (ABDW for D-22 or U-12, etc) and hadn't the foggiest idea of what pressures they started with and or what pressures they need to end up with. Some end up OK, some end up with flat wheels, some end up with not enough brake...

G.F.Payne
Baltimore, MD

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George F.Payne
Baltimore, MD


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 Post subject: Re: J-36 relay valve
PostPosted: Tue Jul 04, 2017 2:24 pm 

Joined: Sun Aug 22, 2004 9:54 am
Posts: 794
Location: NJ
OK, that 36% makes sense. These came from LIRR FA cab cars some years ago, which I was helping convert to 26-FNL. I vaguely remember a connection into the filling piece, as well as into the pipe bracket itself. If I had any idea that I might be using these valves (as cores) on another project, years later, I would have paid more attention, taking things apart, as to what was piped to what and where... Live and learn.

The FA project has generated lots of 24-RL cores; if anyone is interested in 24 parts, send me a PM. I also have several extra adaptor plates for 6-FNR distributing valves, providing ports 2A and 2B, as used on a 26-FNL conversion. This system is seen on pages 595 and 596 of the 1980 Loco and Car Cyc.


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 Post subject: Re: J-36 relay valve
PostPosted: Wed Jul 12, 2017 11:12 am 

Joined: Sun Aug 22, 2004 7:23 am
Posts: 436
Location: Strasburg, PA
Catalpa wrote:
... Too many people and some pretty well known organizations have switched brake valves (ABDW for D-22 or U-12, etc) and hadn't the foggiest idea of what pressures they started with and or what pressures they need to end up with. Some end up OK, some end up with flat wheels, some end up with not enough brake...

Hear, hear, George. Mount BC pressure taps and run static and running tests, at a minimum. Better yet, hire a reputable company to do the design work.

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 Post subject: Re: J-36 relay valve
PostPosted: Fri Jul 14, 2017 6:34 pm 

Joined: Sun Aug 22, 2004 9:54 am
Posts: 794
Location: NJ
Good advice above, thanks. The project I'm working on, with others, is really a matter of 'reverse engineering' a tried and true commercial package, so no real engineering is involved; its all been done. I was just trying to see if we can use a good supply of J-36 valves already on hand.


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