Pound Sand, Sucky Motor Club

[mathnerd]

Thanks, Wolfie, for the more detailed explanation!

Chromatix, I could lose days of my life watching Russian trucker/dash cam videos.

[Argabarga]

In case you are curious (at least in the US, the only one I'm familiar with) the air brakes on trains work the same way.

The brake shoes on each freight car are spring loaded and constantly trying to turn "on" when the system is pressurized. Only air pressure provided by compressors in the locomotives keeps them off by equalizing the overall pressure. (next time you see a train, look between the cars, the rubber hose under the couplers is carrying the air supply from one car to the next, the "brake pipe" as it's known in the biz)

The brakes are applied by reducing the pressure, less air, and the brakes come on, reduce it more, they come on harder, and suddenly lose pressure, and they come on HARD to stop everything.

I'm simplifying it a bit, but that's basically it, and why almost every single "Runway Train" move is just that, a movie, absent negligence or sabotage, there's no way for a train to just suddenly and inexplicably lose it's brakes, and, any car cut from a train in motion is going to instantly grind to a stop.

[raudf]

My dad replaced the jack on his truck with one that he can more easily use. He has trouble bending over, so he has a foot powered jack that is more sturdy than the factory jack. His big curse is the fact that the spare is UNDER the bed and requires crawling under to get to it. I'm thinking of getting a tire holder set up in the bed to spare his pride.

I do think everyone should learn how a tire is changed. Even if you don't do it yourself, you'll be able to tell when someone has screwed it up, plus, you'll be able to tell the person helping you where everything is located! (Which is why it took me 10 minutes to change the tire on the MIL's car. She didn't know where anything was and didn't CARE.)

[ADeMartino]

I'm simplifying it a bit, but that's basically it, and why almost every single "Runway Train" move is just that, a movie, absent negligence or sabotage, there's no way for a train to just suddenly and inexplicably lose it's brakes, and, any car cut from a train in motion is going to instantly grind to a stop.

It's UNLIKELY for a train to lose brakes, yes. But not impossible.

http://en.wikipedia.org/wiki/CSX_8888_incident

[Argabarga]

It's UNLIKELY for a train to lose brakes, yes. But not impossible.

http://en.wikipedia.org/wiki/CSX_8888_incident

I almost wondered when someone would mention "Crazy 8s". Well, the engine brakes worked just fine, it was all the others that didn't.

Like I said, it doesn't happen absent NEGLIGENCE, like getting off a train when you're the only one on it :P

[wolfie]

Holy shit! That's worse (in terms of how the runaway started, not in terms of consequences) than Lac Megantic. In Lac Megantic, the train was parked during a crew rest period, with the engine running to keep up air pressure in the brake system (some car brakes were set, but clearly not enough). There was a fire on the engine, and part of the protocol is to shut it down. Air pressure leaked down, the engine brakes released, and it rolled downhill.

[protege]

It's UNLIKELY for a train to lose brakes, yes. But not impossible.]

Here's another one from 1953. A famous wreck, in fact. What happened, was one of the brake valves managed to close itself. Apparently, the car's rocking motion nudged the valve against the frame...slowly closing it. End result was the Federal Express roaring into Washington DC's Union Station at 45mph...smashing through the track bumper, the stationmaster's office, newsstand...before the locomotive's weight sent it through the concourse floor, and into the basement

[ADeMartino]

Like I said, it doesn't happen absent NEGLIGENCE, like getting off a train when you're the only one on it :P

Well, the reason I bring it up is that it tends to contradict the 'automatic braking in the event of air pressure loss' feature. In the 8888 incident, it is stated that the cars coupled to the locomotive were not hooked to the loco's air system. Without air pressure, the loco should not have been able to move 47 cars with the brakes applied - at least, not at 50+ miles per hour achieved during the incident.

It's not the only discrepancy. In 2005, a string of parked rail cars got rolling - not even hooked to a locomotive. I think in the end the string of cars went like 12 miles or something. Again, no air pressure should have locked the brakes and prevented the incident.

Then there's the Lac Megantic incident, where as Wolfie stated, the air brakes of the sitting train bled down after the loco was shut down, and the whole works began to roll.

I know, I was always told that the air brakes were set up to apply in the event air pressure was lost - and indeed, that way seems to make a great deal of sense. But the three incidents I've described don't make sense if that truly is the way air brakes work. Unless I'm missing some technical detail somewhere.

[Shalom]

I don't think that's how it works.

Train air brakes are applied by air stored in reservoirs on each car, not by springs. If the air leaks down and there's nothing left in the reservoir, then the car has no brakes at all, unless someone turns the hand brake wheel (which they should do whenever leaving a car by itself). It's possible to disconnect a car from a train and keep air in the reservoir for a while (by turning the angle cock at each end of the car), but sooner or later it will leak down.

I'm a bit fuzzy on the details, but I think the way it works is, first the locomotive pumps air down the line until all the reservoirs are charged up. As this happens, first the brakes apply, then eventually, once the pressure in the reservoirs is equal to that in the brake line, they release again. Lowering the air pressure in the line such that it is below the pressure in the reservoirs will cause them to reapply.

See the section "Westinghouse air brake" in this article.

Another article with photos here. excerpted from "Railroad Fire Prevention Field Guide".

(Incidentally, George Westinghouse, inventor of the above, supposedly sent a letter to Cornelius Vanderbilt, CEO of the New York Central & Hudson River Railroad, asking for funding to work on his invention; Vanderbilt sent him a one-line reply: "I have no time to waste on fools." Westinghouse took his invention to the Pennsylvania Railroad instead and made his fortune thereby. Later, when Vanderbilt wanted to implement air brakes on his own lines, he wrote to Westinghouse asking for a meeting. Westinghouse sent him back the exact same words, "I have no time to waste on fools.")

[Argabarga]

Yeah, that's it, the system goes through two stages as you start to air it up, it needs an initial pressurization to set the brakes, and after that, a second pressurization to get them to release.

Once you stop the train and disconnect everything, the system isn't perfectly sealed and over time, the air will leak out to the point where the cars can roll freely, that's why proper procedure is to either chock the wheels or set the handbrakes once you've unhooked.

In yard operations, it's common to not air up the train since at slow speeds, one or two engines are enough to brake short cuts of cars as you're building up a train. So, when the train they were building went runaway, the only brakes that were active were those on the engine, and those alone can't stop something like that when it's built up enough momentum.

And Vanderbuilt did indeed tell Westinghouse he was a fool for believing he could "stop a train using nothing but wind" yeah, how'd that work out for ya chief?

Prior to it's invention, those handbrakes were the only thing that could stop a train, and the original job of the "Brakeman" was to run along the cars and set the handbrakes one-by-one as needed. Turnover for that job was, unsurprisingly, appalling.

[It's me]

Train brakes are a bit different.... cars need to be able to roll freely so they can be humped, but need to the brakes to automatically apply if the train comes apart.


http://cs.trains.com/trn/f/111/t/175931.aspx
Which has links to here:
http://www.trackmobile.com/trainairbrakeexpert.htm

Edit: Argabarga beat me in posting, but the links are still interesting!

[JarethsPet]

I had a motor club get lippy with me when they called.

They said their client was on the turnpike. I asked where. They said on the PA turnpike. I asked WHERE, come to find out that they did not know. Politely I asked if the customer could get out of the vehicle to find the mile marker which was every 10th of a mile. The motor club told me that she was too scared to. Then after telling them we cannot go out without knowing the mile marker the club asked....

Can't you go out and look for them?

THE TURNPIKE IS OVER A HUNDRED MILES LONG. I even flat out said to the motor club, "If she doesn't know where she is, how are we going to find her?"

*click*

[Argabarga]

Scared to get out of the car?

This is PENNSYLVANIA lady, not TRANSYLVANIA!

And I'm not surprised, as technology in theory is working from one end to make life easier, people are simply deciding to abdicate more and more effort on their end so the end result is the same as it always is.... stupid.... helpless.... MORONS wanting to know why you won't help them in such SIMPLE situations!

[JarethsPet]

Scared to get out of the car?

This is PENNSYLVANIA lady, not TRANSYLVANIA!

And I'm not surprised, as technology in theory is working from one end to make life easier, people are simply deciding to abdicate more and more effort on their end so the end result is the same as it always is.... stupid.... helpless.... MORONS wanting to know why you won't help them in such SIMPLE situations!

PREACH!

My favorite is informing people of dialing *11 when they won't give me a mile marker.

"Well why do I have to do that?"

If you won't listen to me about finding your mile marker the Turnpike Commission will explain it much better with more authority, because they don't want your car clogging up the road way somewhere and will discover exactly where you are.

[ADeMartino]

Train brakes are a bit different.... cars need to be able to roll freely so they can be humped, but need to the brakes to automatically apply if the train comes apart.


http://cs.trains.com/trn/f/111/t/175931.aspx
Which has links to here:
http://www.trackmobile.com/trainairbrakeexpert.htm

Edit: Argabarga beat me in posting, but the links are still interesting!

Thanks to you and Argabarga for clarifying that; it makes much more sense now. Clearly, there WAS a technical aspect I was overlooking.