Emergency Brakes On Trains

[Cartigan]

I was watching the episode of “I Love Lucy” where Lucy keeps stopping the train by pulling the emergency brake in the car. I have never been on a train like that but I’ve been on the subway and I see the emergency stop in each car.

First question, why is it there? I am assuming a long time ago when trains were primative there was a good reason for it.

Second question is what is the fine for pulling the stop? I’m sure they would’ve arrested Lucy in real life for pulling the emergency brake. Her excuses were “My husband wasn’t yet on the train.” (Lucy forgot her purse and Ricky ran to get it) The next reason was she couldn’t find her mother or child. (Her mother and kid were in the next car but the conductor found out there was a ticket error so they had to move). The next time was to catch the diamond thief.

[Q.E.D]

The emergency brakes are there because the engineer may not always be aware of a serious problem until it’s too late. For example, if the last car becomes partially derailed, it could eventually pull the rest of the train off the tracks but the engineer, being all the way up front, won’t realize there’s a problem until it’s too late. In this case, a passenger in that last car will certainly realize something is wrong as the car starts to lurch and bounce around violently. Pulling the brake in this situation would be perfectly appropriate. Less serious situations, such as medical emergencies, are best handled by summoning a conductor–on most lines, you’ll be able to find one no more than a car or two away. Pulling the brake causes the train to stop completely and the engineer cannot override the braking until after the train has stopped. The crew has to then check the train to make sure no problems were caused by the hard braking and that the train is safe to move again, resulting in delays of several minutes.

[Quartz]

Are you sure about that? On the London Underground, pulling the Emergency Stop merely alerts the driver who will then stop at the next station, unless the situation warrants more immediate action. London Dopers can give chapter and verse but it was written underneath the handle when I was last in London a month ago.

[Q.E.D]

Pretty sure, at least here in the US. From here:

The emergency brake, located at the end of the coach and identified by a red handle with an instructional sign, irrevocably stops the train, which can delay the train by at least five minutes and sometimes more. This also delays the ability of emergency response teams to reach the afflicted passenger.

“We unfortunately had such a situation arise very recently when a rider suffered a seizure, and a fellow passenger mistakenly thought that pulling the handle would summon a conductor. Instead, it stopped the train,” said David Snyder, VRE’s Superintendent of Operations, Safety and Security. “The engineers cannot override an emergency brake.”

[seosamh]

@Quartz

Are you sure about that? On the London Underground, pulling the Emergency Stop merely alerts the driver who will then stop at the next station, unless the situation warrants more immediate action. London Dopers can give chapter and verse but it was written underneath the handle when I was last in London a month ago.

Yep - that’s right.

In the old days, pulling the Passenger Emergency Valve (PEV) as it was known would actually open up a port in the braking system, letting out the air and activating the brakes. The guard would have to come and reset the valve before the train could recharge its air. Nowadays, the PEV merely alerts the driver to a problem. If any part of the train is still in the platform, he or she will stop the train; but if the train has completely left the station, he or she will wait until the next station stop. The driver can tell where the train is in relation to the station by light-blue markers at the side of the track.

[BlakeTyner]

I love railroad threads, for I am a railroader.

First a very simple primer on train brakes:

There is an air compressor and a couple of large tanks (called the Main Reservoir) on the locomotive. The compressor charges the main res and the train line brake (called the Brake Pipe) to a certain pressure. For freight, 90psi; for passenger, 110psi. The Brake Pipe extends the entire length of the train. The air hoses that connect each car are part of the Brake Pipe. Each car will have its own reservoir that is charged with air up to 90 or 110 psi. It is connected to the Brake Pipe by a triple valve that acts independently, depending on what the air pressure is on each side of it. If the res side is showing 0 while the Brake Pipe is increasing, the valve will open and allow that air into the res.

The entire train, each car, gets charged with air.

Once everything equalizes, which can take minutes on a long freight, the brakes on the train are released. If the engineer makes an application, he moves his brake handle and reduces the Brake Pipe to, say, 80psi. (The 10psi that he releases vents into the atmosphere, usually in the cab where he can hear it.)

Now, the triple valves on each car see that there is 90psi in the res, and 80psi in the Brake Pipe. The triple valve opens and allows the 10psi from the res into the car’s Brake Cylinder. That pressure goes into the (smaller) Brake Cylinder, where it now exerts roughly 2.5 times more pressure; this gives us effectively 25psi in each car’s Brake Cylinder. That 25psi pushes the brake shoes onto the wheels.

What’s known as a train’s “Emergency Brake” is really just a bigger hole in the brake valve. The engineer moves his handle there, and ALL the air in the entire Brake Pipe is vented into the atmosphere. The triple valves see 90psi in their car’s reservoir and 0psi in the Brake Pipe. The triple valve opens ITS big hole, and lets all the air in the car’s reservoir into the car’s brake cylinder. The brake shoes lock onto the wheels with their maximum force. (There is a limit to the amount of air that can go into the Brake Cylinder, so you’re not actually getting a 90psi x 2.5 application to the brake shoes; IIRC, the maximum application is somewhere around 65psi)

The Emergency Brake cord in passenger cars (at least in the US) does the same thing from a different location; it vents the entire Brake Pipe into the atmosphere. The same thing happens, it just starts in THAT car and works its way forward (and back) rather than starting with the first car behind the locomotive. The same principle allows a train to come to a stop if it breaks in half - the air hose would release and vent the brake pipe into the atmosphere, forcing an emergency application on both halves of the train.

**For the sake of simplicity, I’ve left out things like the Equalizing Reservoir, and the Auxilary Reservoir. If you want a hugely detailed breakdown of train brakes, check out Al Krug’s Page

Why is it there?

In passenger trains, the conductor (who is the boss of the train; he dictates ALL movements, the engineer merely operates levers) is generally not in the locomotive. He’s on the train itself, collecting tickets and such. If he needs the train to stop and cannot get the engineer on the radio, he can stop the train. Incidently, even on freight locomotives, the conductor (who is up front) has an emergency brake valve on his side of the cab for the same reason.

It also allows him to stop the train quickly if the train is in a reverse movement, where the engineer cannot see where he is going. The conductor will be there to provide the eyes; if he sees a baby crawling on the track, for example, he can “big hole” the train himself.
What is the fine for pulling it?

That I’m not sure about. I’m not aware of a rule such as the federal “interfering with a flight crew” one. It may depend on the state. Regardless, if found out, one wouldn’t expect to remain on the train. Conductors sometimes call ahead and have a police officer waiting at the next station (or at the next road crossing.) I’ve seen that myself on Amtrak, when a passenger urinated on someone in coach. They stopped the train at a road crossing and the police met us there.
Every once in a while, a passenger needs to pull that cord as well, but they seem to be intended more for the train crew.
There are instances like mentioned above, where the chord is simply a communication line (usually pneumatic) that will sound a chime or bell in the locomotive. My guess is that comm cords are more likely on light transit type lines.

[Black_Train_Song]

Hey there Blake. Fellow railroader saying hi. I’m a conductor in freight and I cringe at the idea of ever having to pull that valve. No one’s told me what 11,000 tons of train behind me will do if I pulled that thing at say, 40mph. I can’t imagine it being pretty though.

[spingears]

@Q.E.D.

The emergency brakes are there because the engineer may not always be aware of a serious problem until it’s too late. For example, if the last car becomes partially derailed, it could eventually pull the rest of the train off the tracks but the engineer, being all the way up front, won’t realize there’s a problem until it’s too late. In this case, a passenger in that last car will certainly realize something is wrong as the car starts to lurch and bounce around violently. Pulling the brake in this situation would be perfectly appropriate. Less serious situations, such as medical emergencies, are best handled by summoning a conductor–on most lines, you’ll be able to find one no more than a car or two away. Pulling the brake causes the train to stop completely and the engineer cannot override the braking until after the train has stopped. The crew has to then check the train to make sure no problems were caused by the hard braking and that the train is safe to move again, resulting in delays of several minutes.

The air brake line will STOP the train when and if it is depressureized by pulling the emergency cord OR if the line is opened by a lost/derailed car coming loose/disconnected from the train.
The brake line must be secured before the brakes can be pumped up and the train can move onward.

[spingears]

@spingears

The air brake line will STOP the train

OOPS. Missed or skipped the full treatise. :rolleyes:

[BlakeTyner]

@Black Train Song

Hey there Blake. Fellow railroader saying hi. I’m a conductor in freight and I cringe at the idea of ever having to pull that valve. No one’s told me what 11,000 tons of train behind me will do if I pulled that thing at say, 40mph. I can’t imagine it being pretty though.

It can lead to an ugly situation for sure, but sometimes there’s no other choice. I’m sure it’s been drilled into your head as much as mine: “When in doubt, STOP the movement.” Flat spots in the wheels, broken knuckles/drawbars, etc can be replaced.

Highball.

[David_Simmons]

Sometimes the brakes aren’t enough.

Not long after the Cajon Pass runaway described in the cite, another train carrying the mineral Trona ran away in the same place, derailed on a curve in San Bernardino and caused a lot of damage. And then not long after an underground pipeline failed at that curve causing a bad fire in the neighborhood.

An investigation showed that the train was a lot heavier than reported on the paperwork and not enough locomotives for adequate dynamic braking had been provided.

Cajon Pass has an average grade of 3% which is pretty steep for trains.

[TheLoadedDog]

@Black Train Song

Hey there Blake. Fellow railroader saying hi. I’m a conductor in freight and I cringe at the idea of ever having to pull that valve. No one’s told me what 11,000 tons of train behind me will do if I pulled that thing at say, 40mph. I can’t imagine it being pretty though.

Yep. Here in Australia, it’s called “pulling the tail” which dumps the air as adequately posted upthread. It’s not something you do lightly because it creates a violent stop. But there are other, human, issues too…

On Australian trains, as in the US, the guard (conductor) is theoretically the boss of the train. Guard says jump, driver asks how high. In theory.

In the real world though, it’s not so simple. You become a guard before you become a driver, so the driver is senior. The driver also gets paid more. The drivers tend not to respect the authority of the guard over them, and the guards are reluctant to do certain things (such as dumping the air).

If you Google “Waterfall rail disaster”, you will find a situation in which people lost their lives because of this reluctance to exert authority over the driver. A Sydney suburban double deck EMU left a station in the southern suburbs, and the driver notched up for a fast but brief run along a straight. In four notch, he suffered a fatal heart attack. He was a big man, and the subsequent inquiry determined that the weight of his legs exerted enough downward pressure on the deadman device (a pedal in this case) to prevent it from activating. The train left the metals at 110kmh in a curve rated at 60, killing about eight people. The inquiry determined that the guard of the train had been aware that something was wrong due to the high speed (many passengers testified that they knew something was wrong) but was reluctant to open the brake valve because it was “not done” to question your driver’s dribving.

[Black_Train_Song]

TheLoadedDog , that’s pretty much the way things work here also except that where I work they’ll definitely hold the conductor accountable if something goes wrong. So any good conductor tends to open his mouth when he should and the engineer usually will listen. Most engineers where I work tend to look out for their conductors though.
In most situations the entire crew is held accountable as far as train handling goes. Conductors are required to know the speeds and will get fired right along with the engineer if they’re caught speeding. The conductor is the one who catches hell when the crew sits around for a little too long before getting to their train and for any other mundane incidentals that occur.

[Billdo]

According to the MTA in the New York City Subways:

Using the Emergency Cord
Use the emergency cord only to prevent an accident or injury. For example, if someone gets caught between closing subway car doors and is being dragged, pull the cord. But if your train is between stations and someone aboard becomes ill, do not pull the emergency cord. The train will stop, preventing medical professionals from reaching the sick passenger. A sick person is better off if the train goes to the nearest station where police and medical services will be waiting or can be quickly summoned, without interruption.

[Sunspace]

On the subway in Toronto there’s an emergency stop handle behind glass, which must be broken to access it. It’s mounted high up, by the top corner of one of the doors.

There is also a separate emergency alarm, which is yellow and goes along the top of the windows and has instructions on when to press it. It signals the train crew. I’ve seen the emergency alarm activated once or twice, but never the emergency stop.

[David_Simmons]

@Billdo

According to the MTA in the New York City Subways:

Have things changed? When I was in New York just after WWII, the train wouldn’t start unless all of the doors were fully closed. Some friends and I went to New York to see a Dodgers game. As we came toward the train the doors were closing so a guy on board held one door open so the train couldn’t leave before we got there.

(Warren Spahn pitched for the Braves in his rookie year.}

[Q.E.D]

@David Simmons

Have things changed?

Nah, they’re sill like that. However, safety mechanisms can fail so it’s still a remote possibility that something like that could happen.

[David_Simmons]

@Q.E.D.

Nah, they’re sill like that. However, safety mechanisms can fail so it’s still a remote possibility that something like that could happen.

True. A little redundancy never hurts in such things.

[Eric79]

I was visiting Chicago once and someone pulled the stop in a car and the whole subway train stopped. Since there is only one person driving the subway she had to come back to the car and she cussed out the guy who pulled the cord.

[A.R.Cane]

I recently read, or heard, about some controversy over refitting train cars w/ electrically operated braking. It was claimed that this could dramatically reduce stopping distance, but the RR’s don’t want to invest the money, which would be considerable, to do the refit.