The siding I was talking bout is one they use mostly for repairing cars. There is always a few rubber brake lines laying around. Most of them only have a very small hole in them, and that was enough to get the replaced. Now think about one of them burned badly.

And just like truck trailers, the air pressure is needed to release the brakes, not to apply the brakes. This is a "safety feature" so cars don't start rolling on their own in the rail yard. However, it also means a brake gets applied with a minor hole in the line and can cause an overheating situation.

 

Getting at the truth is as hard today as it was at any time in the past. Popular media like the press and TV are known to be biased in some way or other. It takes effort, real effort to separate the wheat from the chaff on this or any other controversial topic be it a train disaster or war in Ukraine, so establishing facts should be the first step, as best one can, have some basis for an opinion, a fact based opinion.

 

Just my guess from looking at rail cars on a siding near my wife's house. The pressurized air comes from the engine, each car has both metal lines and rubber brake lines. The rubber ones are near the couplers on the end of the cars. If there would be enough heat from a wheel fire, the rubber lines would start to leak. Even though the rubber lines have a steel braid they still have a rubber inner and outer cover that can get compromised and the steel braid won't hold air.

One of the biggest problems with air brakes is if you try to pressurize your brakes solely from the air pressure from the power unit you will have a huge lag in response as the braking vessels take time to fill up which will cascade down the length of the train. Like a semi trailer all train cars have air tanks built into them that is source of air for that car's brakes. There is some form of "relay" valve that uses very little air to actuate and sends air from the tank to the brake chamber to actuate the brakes. On a multi trailer semi application the relay valve also serves as the control signal to the next trailer.

The part that differs according to what I could find is with trucks and trailers there is a line that when pressurized pulls back on the parking brake spring and pressurizes the tank(s) and another line that runs the service brakes by pressurizing a valve that in turn takes are from the tank and sends it to the brake chambers. Trains on the other hand don't have the spring brake and rely on the air in the tank for parking brake. They also work backwards on the control line where a loss of pressure in the control line is supposed to actuate the brake as far as I can tell. On a truck and trailer the control line is pressurized to actuate the brakes.

Basically what should happen as far as I can tell when the air line is severed the air from the on board tank should set the brakes full on which would lock up the wheels sooner or later which will slow the car down, but like with skidding tires there will be a loss of traction... even worse being steel on steel. Maybe that is what was meant and what I would really like to know.

Wikipedia has a pretty good description and I would assume like road trucks the basics of the system haven't changed since it's original version. There are additional valves on trucks and trailers these days to handle automatic braking, ABS, and what not, but at the core is still the same two or three valves that have been the back bone of the system since it was first standardized and approved by the DOT. I would guess trains are the same in that regard.

Edit...
Another possibility I was thinking, but it escaped before I got it down was if somehow the air lines had melted closed in such a way that they had enough pressure trapped in the system then it would cause the brakes to not function. That would fall along the lines of a one and a million rarity that even the best designed system couldn't handle. In that case an electric system would have been most useful provided there was still power to the unit in some form.

 

And just like truck trailers, the air pressure is needed to release the brakes, not to apply the brakes. This is a "safety feature" so cars don't start rolling on their own in the rail yard. However, it also means a brake gets applied with a minor hole in the line and can cause an overheating situation.

That's the way I always thought too, but if that was so how do the "hump" cars in a rail yard? Doing that they are never hooked to any air or coupler, they just get pushed and couple to the line of cars being assembled. and then a brake man connects the hose couplings.

They ought to bring back brakemen. The guy running down the string of cars turning the brake wheel on top of each car. They don't even have manual brakes anymore.

 

And just like truck trailers, the air pressure is needed to release the brakes, not to apply the brakes. This is a "safety feature" so cars don't start rolling on their own in the rail yard. However, it also means a brake gets applied with a minor hole in the line and can cause an overheating situation.

Yes and no. The spring "parking" brake side of the brake chamber uses air to release it. The service "road brakes" side of the chamber uses air to pressurize and actuate the brakes.
Most trucks and trailers will hold the spring back down to 60 psi. After that the spring will overcome the air and the brakes will start to drag.

Trains on the other hand do not have a two chambered brake chamber. Air is used to actuate the brakes in all instances.

 

They ought to bring back brakemen. The guy running down the string of cars turning the brake wheel on top of each car. They don't even have manual brakes anymore.

Unstoppable was a movie starting Denzel Washington and Chris Pine has a scene exactly as you mentioned. The movie was based on the true story of a runaway CSX freight train. In the movie the runaway train was 777 and in life it was 8888. The actual incident took place... ready for this? Ohio. The CSX 8888 incident closely parallels the movie but the movie takes place in PA. Go figure huh? Your comments reminded me of a scene in the movie. Then too consider the Hollywood touch.

Ron

 

Here's the most thorough explanation yet for the train derailment in East Palestine

That cleats up a lot of my questions... Maybe they'll modify their procedures to recognize a significant increase in temperature over a relatively short span should be cause for alarm.

 

Unstoppable was a movie starting Denzel Washington and Chris Pine has a scene exactly as you mentioned. The movie was based on the true story of a runaway CSX freight train. In the movie the runaway train was 777 and in life it was 8888. The actual incident took place... ready for this? Ohio. The CSX 8888 incident closely parallels the movie but the movie takes place in PA. Go figure huh? Your comments reminded me of a scene in the movie. Then too consider the Hollywood touch.

Ron

The movie was a HUGE departure from the actual incident. In both, there was a train that was moving down the tracks without anyone on board. That's about the extent to which they were similar. Actually, there were some other similarities, but they were almost all wildly exaggerated to the point of bearing only superficial resemblance. Most of the movie was effectively made up out of whole cloth.

 

Movie night at home must be a treat for the family.

 

After thinking more about the number of derailments happening, it seems like the number is surprisingly small. Think about the width of the rails, the weight the cars hold and the distance above the wheels the weight is located. The whole thing is a disaster looking for a place to happen. Instaed of the expense of widening the track distance, the railroads are happy to pay out for loss of cargo and property damages, when compared to the money they make.

 

The movie was a HUGE departure from the actual incident. In both, there was a train that was moving down the tracks without anyone on board. That's about the extent to which they were similar. Actually, there were some other similarities, but they were almost all wildly exaggerated to the point of bearing only superficial resemblance. Most of the movie was effectively made up out of whole cloth.

Yes and that's why I included...

Then too consider the Hollywood touch.

I remember in the movie they did mention the classic "based on a true story". I was also surprised that unknown to me the actual event the movie was based on took place in Ohio.

I guess that there is something like 1,000 train derailments every year in the US. While many amount to nothing some make a big splash as this recent one did. There have been others with devastating results. I tend to watch both Engineering Disasters and Air Disasters. I was surprised how many train derailments turn up. Paulsboro train derailment, chemical spill is another of many. Note the chemicals involved. Again, I was not aware of just how many trains find their way off the tracks annually.


Ron

 

The whole thing is a disaster looking for a place to happen. Instaed of the expense of widening the track distance, the railroads are happy to pay out for loss of cargo and property damages, when compared to the money they make.

There you have it.

Ron

 

Instaed of the expense of widening the track distance, the railroads are happy to pay out for loss of cargo and property damages, when compared to the money they make.

Although I agree with you in principle ... I cannot possibly imagine what it would cost to not only upgrade the entire railway infrastructure, but also re-adapting every single rail car out there ...

 

In our economy there are only two people who pay for everything...

The taxpayer and the consumer.

And guess what...you are both of them.

It's a long story how that works, but it has to do with everything a business has to pay for is just another expense on the leger, that must be balanced on the revenue side, but that's only the beginning of the story.