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Discussion Starter #1
Anyone have a clue what this device is?



It sits atop the smaller of two air tanks on the tender of #21. 



From another photo, I'm reasonably certain that line [C] is connected to the large air tank to its immediate right, which feeds air through line [C] to pressurize the small tank.  The large tank, btw, gets pressurized directly from the air pump on the locomotive.  The pointed shadow [A] makes it look like is conical.  [D] looks like it could be a union or the body of a globe valve, though I don't see a valve handle.
 
Any ideas what this device is and what purpose it serves?
 

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Discussion Starter #3
The two tanks are probably your main and equalizing reservoirs.
Thanks for the response Matt!  Now please forgive my ignorance and explain what an equalizing reservoir is. /DesktopModules/NTForums/themes/mls/emoticons/blush.gif

The larger of the two tanks was, I believe, used to pressurize the oil bunker.  I had thought perhaps the small tank was the brake reservoir, which got charged from the large tank, which in turn was charged from the air pump, and that perhaps the device was some sort of clack valve which prevented the brake tank pressure from bleeding back into the large tank when it's pressure dropped.

Ultimately I'm trying to figure out what the device looked like in order to make one.
 

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Ok. Pictures being worth a thousand words... try this:

http://en.wikipedia.org/wiki/Image:Westinghouse_Air_Brake_piping_diagram.jpg  

That's a typical locomotive air brake system. 

The interesting thing is, if that's really a triple valve (which, if you look at the picture in the first article I linked, it really kind of looks like,) it could be that the tender has brakes like the flatcar it's descended from, in which case the brake system would look more like this:

http://www.railway-technical.com/air-block.gif 

in which case you'd have the main reservoir for the system, the triple valve, and the auxillary reservoir for the flatcar/tender brakes.

That'd be unusual, because on every steam engine I've ever dealt with, the brakes on the tender operate with the independant brakes, not the automatic, as if it were part of the locomotive (which, in essence, it is) and not a car on the train.

Matthew (OV)
 

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It is quite normal for the loco's brakes to also be part of the Automatic system, complete with aux tank for the loco with tripple valve, along with a straight air override for the loco alone. The UP owned NG line in Colorado were like this, CCRR, DSP&P and ultimately C&S. While the D&RG from the 1880s onward used Automatic air for the train with loco only straight air, later being changed to automatic air on loco as well, with straight air override (aux brake).

If you look at the rear of the CCRR, DSP and C&S tenders, you'll see the aux tank mounted on the back with the tripple valve attached, just for the loco's own connection to the automatic system. The larger train tanks were directly below the aux tanks (two tank on rear of tender), until in the case of the C&S, the train tanks ended up on the top of the boiler, or under the running boards, while the aux tank and tripple valve remained alone on the tender rear. Check C&S #60 as an example that you can see today.   Not sure of the current arrangement of the K-27s, 36s etc, however I do recall seeing the aux tank and tripple valves under the cab floor for the 8 driver brakes, so I to think they may well also be automatic air across the entire train, incl loco, with a straight air bypass when required via the use of the 2nd brake stand in the cab...runs air directly from the main air tank to the brake cylinders via alternative path.

David.
 

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Discussion Starter #6
You guys are great!!  Thanks so much!


No matter how much I stare at the photos, I can see no brakes on the drivers.  However, the brake staff on the tender certainly implies at least manual brakes (though the shoes must be internally hung since I can't see them either), and the air pump on the loco implies air brakes.  Additionally, the loco was built in 1901, 29 years after Westinghouse patented his air brake system, and 8 years after Congress passed the Safety Appliance Act, so it would make sense that the NPC roster had air brakes by that time.

Does anyone make castings of triple valves that might work?
 

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Air to tender brakes only was pretty normal. Thats where it started before loco drive wheel brakes were fitted. From what I've seen, when loco air brakes were fitted to the drivers as well, another Aux tank and tripple valve was fitted just for those brakes. Hence a loco and tender, if fitted with air brakes to both units, would have two Aux tanks and two tripple valves...one for each separate units.

Dono who makes castings, maybe ask Ozark.

David.
 

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Interesting. The reverse is Tweetsie #12, where the automatic and independant are NOT linked .... usually making an application on the automatic brake will cause the independant brake to come on as well .... with #12 the two systems are NOT linked, or so their engineman told me last I was there.  Making a reduction on the train does NOT cause the brake cylinder pressure on the independant to come up making it really .... independant!

I didn't know that about the C&S locomotives, etc. I saw the extra air tanks, and assumed they were simply piped in with the main reservoir on the locomotive. Perhaps the "linked" automatic and independant were developed to avoid having to install the whole independant system on loco and tender --- you still end up with a full application on the engine and tender in the event of a "dump" on the train line, without a seperate system.

Matthew (OV)
 

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Matt,
Its not about being linked, the engine still has a direct air loco brake, but it by-passes the tripple valve and uses the same brake cylinders and brake rig. Two brake stands in the cab as usual. Difference is, while braking in normal conditions, the loco and the train all brake together via the automatic system without the need for the crew to brake the train with one hand and the engine with the other, while trying to hang onto the throttle with a third hand! The engine brake comes into use mostly when running light around the yard, or wanting more braking than the automatic will give. There are lots of variants to the plumbing, but tripple valves on the loco for engine brakes are pretty common.

The 1882 system on the DSP Mason Bogies and early DSP and CCRR UP system had the engine brake very much an emergency brake, with the stand right up the front end of the cab, virtually out of reach to avoid confusion. Later systems have the two stands side by side.
Check out the drawings in the Rail driver encyclopedia for a bit more on the systems. Interesting bout speaking with the crews, as I often do, and brakes come up a lot (becuase there are different setups), the guys I speak to know the system perfectly in order to operate the brakes, (as you'd expect) but only maybe 5 out of 10 of them knows exactly how the system is plumbed on their loco! For that you need to speak to the shop guys.

I dont envy those Tweetsie guys, having to work both brake stands to control the train! Thats how the D&RG system was too after the full straight air system of the 1870s was replaced but auromatic air on the trains, but locos remained with straight air only, and no tripple valves on the engine at all.

Have fun!
David.
 

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Dwight,

You need to send your photos to the FBI and have them do there magic on em:D

Heck they ain't gots notten better to do:)

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