Re: Express box brake system layout


Dennis Storzek
 

--- In STMFC@yahoogroups.com, "steve l" <stevelucas3@...> wrote:

Just curious, Dennis. Is the "wig-wag" valve for graduated release located on the pipe bracket (I'm assuming so), or near the brake cylinder? Suggestions for modelling this if it's a visible feature on the brake gear?

Steve Lucas.
Boy, every time I get involved with an air brake discussion, I end up spending hours looking for diagrams I know I've seen before. It's a shame that Westinghouse didn't have ONE all encompassing catalog where one could identify any component.

That "wig wag" has a proper name; it's a "Duplex Release Valve." It normally mounts on the service portion of the AB equipment. The diagram in Gene's materials shows a second mounted on the "front" of the pipe bracket (the side opposite the ports for the pipe connections. The 1957 CBC shows a diagram of "AB Freight car brake equipment" that includes this feature, in two alternate locations, labeled "brake cylinder release valve." The other location is on the pipe to the brake cylinder. This diagram must be showing all the options available with standard AB equipment, since it also shows an automatic ratchet type slack adjuster piped to a port on the brake cylinder.

The New York Air Brake Co. section of the same book shows a photo of this valve installed on the pipe bracket; they identify it as a "QRR Brake Cylinder Release Valve portion." In both cases, it must require a pipe bracket with custom drillings.

The AB-1-B equipment is also illustrated in both the 1953 and 1957 CBCs. It does have some interesting additional equipment; a thin slice (my guess, maybe 1.5" thick) that sandwiches between the pipe bracket and the service portion of the valve, that has an additional pipe port. This additional pipe runs to a T in the signal line, and automatically varies the function of the AB valve depending upon whether there is air pressure in the signal line or not. With no pressure in the signal line, the valve functions as a freight valve, with pressure, it more closely matched the characteristics of passenger equipment.

In addition, both the Westinghouse and New York diagrams show an additional small valve remotely connected to the train line; both companies call this the "A-2-A Continuous Quick Service Valve." I suspect this functioned similar to a modern day relay valve used on long cars.

Biggest problem with using pipe schematics from the CBC is I suspect that some of these features were options, so there is no way to know if they were present on the actual cars in question unless the valves are listed on the BOM.

Dennis

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