What is this (possibly train-related) device?

October 5, 2009 5:59 AM

I saw this thing on a recent trip to a train museum - does anyone know what it is?

On a recent trip to the Rail Transport Museum I spotted this device in one of the older passenger carriages. I suppose I should have noted exactly *which* of the carriages it was, but anyway! As I recall, it was in a Pullman car, which was a sleeper. These carriages are all renovated/restored to varying degrees. As my daughter and I moved to the end section of the carriage, I spied this device on the wall. It kind of looked like a small light. I guess it was the size of my fist. If you look closely at the pic, you can see that it has a wire? cable? coming from the bottom of the device, into a drilled hole in the wall.
I asked the guide what it could possibly be. He had no idea! The device was mounted next to some cupboards that were "flush" with the wall. I suggested opening the cupboard door nearest the device, and seeing where the cable went to. After some difficulty the guide and I did manage to get the door open (he was a pretty cool guide, most museum guides would probably have told me to keep my hands off!), but of course the path of the wire was not visible (it must have gone off to the left of the cupboard).
Here is a closer look at the device. You can see it says "Call Dealer When Red". As you can see, it is red!
These carriages are pretty much stationary, but they are powered (the lights do go on and off, my daughter was playing with some of the light switches and they work as they would have when the carriage was in service), and they do move from time to time, and are even taken out of the museum, and members of the public allowed to ride in them (whilst being hauled by an engine). So even though they are museum displays they are expected to get (very limited) use in the real world.
What in the hell is this thing? Has anyone ever seen anything like it before?

posted by humpy to technology (9 comments total)

Just a guess - maybe "dealer" refers to a croupier? I don't have any idea what it would be for, but I'm interested!
posted by brighton at 6:12 AM on October 5

That looks like a narrow-bore gas pipe running into it. It might be a simple pressure indicator - the red could be showing because the white portion, which might usually be held higher up by gas pressure, has dropped, showing the red warning.

If the carriage's lamps were originally powered by gas, perhaps this might be an indicator that the gas supply (however it was stored on carriages in those days) was running low, or there was a leak.
posted by dowcrag at 6:14 AM on October 5 [2 favorites]

You should ask this question here, those guys can answer pretty much any rail related question.
posted by Geckwoistmeinauto at 6:22 AM on October 5

When I was very small, the heating-oil tank in our basement had a nearly identical guage to indicate impending emptiness.
posted by Jode at 6:35 AM on October 5

Yeah, my thought was that that's not a wire but a gas pipe. I'd guess some kind of pressure indicator. Which is why it's sealed. Gas pressure keeps up a sleeve or something that conceals the red thing in the center so that if the pressure drops, the cover falls and you see the red warning indicator. We can see the red thing in the center because the system's no longer pressurized.

But let me emphasize I'm totally guessing. I've never seen anything like that before in my life.
posted by Naberius at 7:26 AM on October 5

I'd put money on dowcrag's answer. It is clearly a 1/4 o.d. copper tubing and the nut is long enough to hint at a ferrule and a flared end - these are used for gas (and often L.P.) In an older application it would be hard, threaded pipe. The device itself I am not familiar with, though.
posted by From Bklyn at 8:08 AM on October 5

I used to have these devices on my old propane tanks. They may not be used any more.
posted by Raybun at 8:32 AM on October 5

Yes that's a pressure gauge for gas. The Dealer you need to call is your gas vendor.
posted by Mitheral at 9:00 AM on October 5

Thanks guys! I guess gas pressure gauge *does* make sense, the sleepers do have running water, perhaps it's heated? There must be a gas tank somewhere...
posted by humpy at 9:45 PM on October 5