54th Anniversary of Hurricane Camille -- BRAKE VALVES

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Saith Comrade Hamiltonius :

>>>>>>>> We had gone only a couple of miles when the engineer called out, "we don't have any brakes." There was a moment of silence from all of us before he said "we are starting down the mountain, and we don't have any brakes." At that the Southern RFE reached over the engineer's shoulder and moved the automatic brake valve into the emergency position, stopping the train. After determining that the brake valve was indeed inoperative in the service application zone, the Southern RFE said to the N&W engineer, "Let me run it. I am more experienced in this than you are." <<<<<<<<

It appears the Southern Engine was equipped with a No. 24 brake valve and the N&W man was only experienced on the newer No. 26 brake equipment. Quite understandable. They work differently.

With the old 24 equipment, the brake handle had to be moved right to the far end of the application quadrant to align the ports to reduce Equalizing Reservoir pressure (and Brake Pipe pressure follows Equalizing Reservoir pressure.) After the desired amount of reduction was shown on the gauge, the brake valve handle was them moved back left to the Lap position, and that stopped the reduction and held Brake Pipe pressure where you had set it (... until leakage caught up with you and applied even more braking effort.)

With the new 26 equipment, any movement of the brake valve handle in the application portion of the quadrant produces a decrease in E.R. pressure, and therefore in Brake Pipe pressure. Tap the handle over just an eighth of an inch, and you will hear another small reduction. And you just leave the handle there until ready to release. That is, the valve does not have to be lapped.

The older equipment which N&W used was the No. 6 and No. 8 brake valve, which functioned just like the 24. I think the 24 brake was introduced in the late 1940s. The 26 was introduced in the very late 1950s and I remember seeing it on the Class J and K passenger engines, but I do not know if any of the freight engines were equipped with 24. The first N&W Diesels came with 24 equipment.

The 26 was the dummy brake... it took a lot of the planning out of the equation. With the 24 equipment, and the older No. 6 equipment, there was no provision for "fine tuning" the application, and if you didn't plan ahead you would stall out the train. I used to catch an occasional local engine equipped with No. 6 equipment, and you had to stay on your toes. And yes, I stalled out a couple trains with those - you just hoped that happened somewhere on a branch line so no one except the crew knew about it !

The No. 24 brake valve was a perfectly good brake valve. The reason it was replaced by the 26 equipment was that Neoprene had been developed and used to make diaphragms inside the new 26 equipment. The 26 was also equipped with "spool valves" or cams internally. These improvements did away with the old heavy brass blocks inside the 24 equipment, which were ported to align with each other when rotated into certain positions. Since the 26 equipment no longer had those surfaces which required lubrication, the ICC/FRA increased the 24 month clean/lube cycle of the 24 valve to 6 years for the 26 valve, which resulted in a maintenance savings. The 26 valves performed marvelously until the Neoprene diaphragm developed a pin-hole, and if that happened the pressure maintaining feature no longer worked and it was Game-Over if you had a long train.

Mr. Lisle will probably want to clean up my memories, but that is fine, too.

Will attach a photo of am old No. 6 brake valve which lives... well, not far from where I am sitting. (The valve to its left, with the handle sticking straight up, is the very early No. 3 "straight air" brake valve...  This was the first form of the brake valve developed by George Westinghouse and I think these were still in service on a few of the N&W M's right up to the end... not sure. And also attaching a photo of the ported brass rotary segment out of an old 24 valve... which lives not far from to the No.6 valve.

-- abram burnett
Our De-Platformed Turnips went to Rumble and Odysee

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A time is coming when men will go mad,
and when they see someone who is not mad,
they will attack him, saying,
"You are mad; you are not like us. "
~ St Antony the Great (+356 A.D.)
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