H-6, H-8 and 24-RL Brake Valves on Engines

[NW Mailing List]

Thank You to Mr King and Mr Lisle for their answers.

I checked the badge plate on what I thought was the H-8 brake valve, and it reads: "O 6 B." The first character in that string might be the alphabetic character O, or is may be the numeral Naught... I cannot tell. So this is some permutation of the No. 6 valve, and  is a case of "My Bad Memory."

In the first attached photo, mounted to the left of the 6 brake valve is an old style S brake valve, which someone gave me about a half century ago.  It had been found in an old storage crate in a railroad shop, and had apparently been re-built before being put into parts inventory (and never used.)  It is identical in operation to the original Type S straight air brake valve used on the first air brake equipment in the late 1860s. "S" of course, stood for Straight Air. I once piped air to the valve, and it still functions and does not leak.

The posititions on the SA valve were:

Handle Forward - Application
Handle Centered - Lapped
Handle to the Rear - Charging

The Engineman had to watch his gauge closely, as leaving the valve in Charging position too long would charge the train to Main Reservoir pressure. (Original values used in the first train air brake systems were 70 psi main reservoir, and 60 psi for the "train pipe.")

Several of the old timers told me that some of the N&W class M engines had used the old straight air valves for the independent brake (i.e. engine brake) up until they were retired. I never saw one in use, but then, at age 79, I am only a Young Pup.

And, as a bonus, also attached is a photo of the rotating segment from a 24-RL brake valve. A real machinist's nightmare.  It is designed to mate against a flat surface into which are machined the various portings. A written explanation would be tedious, so if you are interested, look up the Westinghouse literature. The hand belongs to my #2 Son, and the photo was taken when we tore apart a 24 brake valve a few years back.

The reason the railroads wanted to get away from the 24RL equipment, and go to the 26 brake valve, was that the old valves, with their moving parts and surfaces, must be be torn apart, cleaned and lubricated every 24 months (per ICC/FRA requirements.) But the new 26 valves do not use these mating mechanical surfaces: they operate by cams, spool valves and Neoprene diaphragms (all quite un-interesting.)

And, since I recently received two questions about Retaining Valves, the third attachment will show a retaining valve recovered about 20 years ago from the derelict, decaying old wooden boxcar.  It matches perfectly the drawings given in the 1870s Westinghouse Air Brake literature.  I have not yet opened it up.  There were at least three later versions of the retaining valve (single barrel, double barrel, and rotating,) and some day I will dig them out and photograph them, too.

-- abram burnett
Candidate for Commissioner of Turnips
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