EuclidWhatever caused it, I wonder if that same cause would be possible with ECP brakes.
???
Locomotives were shut down. ECP or not, same thing would have happened.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
henry6he oil companies have to provide the proper vessel for transporting and inform the railroad and first responders in order to assure as safe a trip and shipment as possible. It is their duty and responsibility as citizens.
And the oil companies will counter with "the cars are fine if the railroad would stop crashing them!"
The circle continues.
Will Davis I'm watching this string with extreme interest; you see, I'm in the nuclear field, and this rail accident is one of those watershed events like Three Mile Island, Chernobyl or Fukushima Daiichi. It's an event that is easily going to have permanent repurcussions industry-wide. How the industry centrally responds (AAR), individually responds (each railroad) and how the Federal government and public have responded seem so far quite as I could have expected, with the pleasant exception that the general public isn't calling for the wholesale abandonment of crude oil shipments, tank cars, or railroads. I've bookmarked the AAR response and I will to compare it to how the Nuclear Energy Institute has been responding to Fukushima Daiichi in order to see if there are interesting parallels. Perhaps we can learn something 'bigger picture' by studying both; we shall see. One thing is clear: The spotlight is on, as we say, and it won't go off soon. There will have to be credible responses to equipment conditions, and to the risk (both real and perceived) to populated areas, before it dims any. -Will Davis
I'm watching this string with extreme interest; you see, I'm in the nuclear field, and this rail accident is one of those watershed events like Three Mile Island, Chernobyl or Fukushima Daiichi. It's an event that is easily going to have permanent repurcussions industry-wide.
How the industry centrally responds (AAR), individually responds (each railroad) and how the Federal government and public have responded seem so far quite as I could have expected, with the pleasant exception that the general public isn't calling for the wholesale abandonment of crude oil shipments, tank cars, or railroads.
I've bookmarked the AAR response and I will to compare it to how the Nuclear Energy Institute has been responding to Fukushima Daiichi in order to see if there are interesting parallels. Perhaps we can learn something 'bigger picture' by studying both; we shall see.
One thing is clear: The spotlight is on, as we say, and it won't go off soon. There will have to be credible responses to equipment conditions, and to the risk (both real and perceived) to populated areas, before it dims any.
-Will Davis
As you are knowledgeable about the nuclear energy industry, your comments on this long article would be useful:
http://www.theatlantic.com/technology/archive/2014/06/is-nuclear-power-ever-coming-back/373315/
C&NW, CA&E, MILW, CGW and IC fan
zugmann EuclidWhatever caused it, I wonder if that same cause would be possible with ECP brakes. ??? Locomotives were shut down. ECP or not, same thing would have happened.
I said this: “But I do not know for sure how that would have played out. We still don't know exactly how the air brakes released on that train. Whatever caused it, I wonder if that same cause would be possible with ECP brakes.”
I do not conclude that because Locomotives were shut down, ECP or not, same thing would have happened. You may be right about that, but ECP brakes are charged and controlled differently. To determine if the engine shutdown would have cause the same release scenario with ECP brakes, I would have to know exactly why the brakes released in less than an hour after the engine was shut down. And then I would have to see whether that would happen with ECP brakes.
A quick check on posts suggests the need for a uniform policy on safety with a stopped and shut down Bakken train. There are several different opinions expressed on here as to the proper procedures.
OFF TOPIC, WARNING. NOT RAILROAD RELATED. RAILROAD RELATED POST COMING LATER.
Much of what is in the Atlantic article is the typical P.R. that the "garage sized" and "innovative" entrepreneurial companies / nonprofits are pushing in order to get their fairly radical and not commercially built designs funded and then eventually built. The stuff from UCS is their typical anti-nuclear spew. The article is pretty long for what most folks would like to read, but then again I'd like to think we're increasing our attention spans on average as a society, not decreasing them.
Short reply: There is always a need for, and benefit from, design innovation. However, the diesel locomotive became a practical reality in the 1920's, and it took until the end of the 1950's to push out steam here in the USA after years of practical experience, many further improvements in diesel locomotives, and much data gathering; these new reactors (like all reactors) will take more years than that, and they're starting from a practical standstill with little funding and no interest on the part of utilities that would eventually buy and operate commercialized designs. The ideas fronted under the headings "solutions" are correct, except that I need to point out that light water cooled reactors -- and specifically pressurized water reactors -- are dominating the massive and rapid nuclear build-out ongoing in South Korea, China and elsewhere, not radical designs or even older tested designs (like gas cooled reactors.) This can and should be expected for the foreseeable future.
Light water SMR's have already been built, successfully operated, and proven. This began in the late 1960's with the German-built nuclear powered ship Otto Hahn, first to use what we call an iPWR or integral pressurized water reactor. Their technical viability is not in question; the economics are bad for SMR nuclear plants that are built the same way gigantic 1000 - 1700 MW nuclear plants are. The entire plant needs to be designed innovatively; this is why NuScale Power has won the second DOE fund allocation for development. The demand for such plants is in question in some places (USA, Korea) but they're being built already in others (Russia, Argentina.)
The section describing Three Mile Island is entirely exactly correct. There's also a very keen observation about containment and new plants built to operate at atmospheric pressure that's right on... but adding to that, there is no need to wonder whether or not this would be required. Many years ago an organic cooled reactor was ordered under an AEC program to be built in the city of Piqua, Ohio. This was originally designed with no containment. AEC, after referral from the ACRS (Advisory Committee on Reactor Safeguards) ordered a conventional nuclear plant containment be built because of the proximity to populated areas, which was exactly how the plant was built. The plant is still there today, with fuel removed and in a condition we call SAFSTOR or Safe Storage awaiting dismantlement sometime in the future. It's right along the river on the east bank; you can find it quite easily using Bing maps or some such.
The railroaders might find the industry responses briefly mentioned about Fukushima Daiichi in this article to be of some interest relative to the Mac-Legantic rail accident, but I have some observations to write here later that might help sharpen the focus to see what each can learn from the other.
Railroad Locomotives - My Blog
Euclid I do not conclude that because Locomotives were shut down, ECP or not, same thing would have happened. You may be right about that, but ECP brakes are charged and controlled differently.
I do not conclude that because Locomotives were shut down, ECP or not, same thing would have happened. You may be right about that, but ECP brakes are charged and controlled differently.
No engineer means nobody to place the brake handle in a position that would apply the brakes.
The train line wasn't compromised until the actual derailment so there was nothing to cause the train to go in emergency.
If the engines were shut down and the train line bled off then there was no air pressure in the system to apply the brakes.
Doesn't matter what the control method was, electronic or pneumatic, the first two are absolutely true. The third thing is subject to speculation and is independent of the control type, all brake systems using a train line have leaks in them, some take hours to bleed off, some take minutes. We had a cut of brand new, first trip cars (revenue empties from builder to owner) involved in a derailment and we timed the emergency brake application as holding the cars for less than 1 minute. before they bled off. YMMV.
We went through this whole scenario back in the 1970's with LPG cars. It didn't take any exotic brake system or dedicated equipment, all it took was building a better tank on the tank car. LPG is way more dangerous, way more explosive, way more volatile than any crude including Bakken. If it fixed the LPG problem, it can fix the crude problem.
Dave H. Painted side goes up. My website : wnbranch.com
henry6dehusman Just remember not all crude is the same, the ONLY crude that has had problems is the Bakken crude. The crude from every other formation that railroads have been hauling for over a century does NOT have those same problems. There is also a problem with Congress and the FRA just throwing solutions out there just because they are cool and high tech without thinking about whether they would have solved a problem. ECP wouldn't have prevented Lac Megantic, it wouldn't have prevented Casselton, it wouldn't have prevented the release in Kentucky. Correct. Not all crude is Bakken. But the railroads have to protect themselves and be protected from oil and gas shippers who mislabel or otherwise lie about the product being shipped. The integrity of these energy companies are in question at the moment and their belligerence overwhelmingly disregards and disrespects railroads, other private enterprises, and the public's safety and well being. Yes, I can point fingers and name names but that would be political and politics are not allowed to be discussed to that degree here. Not revealing the volatility and instability of Bakken crude to the railroads or to first responder emergency groups is a blatant example of what I am saying and not some made up conjecture.
dehusman Just remember not all crude is the same, the ONLY crude that has had problems is the Bakken crude. The crude from every other formation that railroads have been hauling for over a century does NOT have those same problems. There is also a problem with Congress and the FRA just throwing solutions out there just because they are cool and high tech without thinking about whether they would have solved a problem. ECP wouldn't have prevented Lac Megantic, it wouldn't have prevented Casselton, it wouldn't have prevented the release in Kentucky.
Just remember not all crude is the same, the ONLY crude that has had problems is the Bakken crude. The crude from every other formation that railroads have been hauling for over a century does NOT have those same problems.
There is also a problem with Congress and the FRA just throwing solutions out there just because they are cool and high tech without thinking about whether they would have solved a problem. ECP wouldn't have prevented Lac Megantic, it wouldn't have prevented Casselton, it wouldn't have prevented the release in Kentucky.
Dude,
What is your problem?
Did you get screwed in a well lease or what?
23 17 46 11
dehusmanWe had a cut of brand new, first trip cars (revenue empties from builder to owner) involved in a derailment and we timed the emergency brake application as holding the cars for less than 1 minute. before they bled off.
You have cited many details which I understand, but I do not exactly follow what points you are making with those details. I agree that once the train ran away, there was nothing that the brakes could have done to avoid the wreck, no matter whether they were ECP brakes or conventional air brakes.
You mention a case where brakes in emergency bled off in less than one minute. First, I am greatly surprised that it could leak off that fast. You must have heard compressed air leaking loudly in a major flow of leakage in order for the cylinders and reservoir to lose their pressure in one minute. I cannot imagine that losing the emergency application in one minute would be anything other than a major defect, rather than just part of normal variation.
If a train went into emergency on a grade and stopped; and then the application leaked off in one minute; the train would run away. Many have commented that their experience is that an emergency application would be expected to hold for many hours minimum, and maybe many days. Of course a small number of cars in the cut might leak down faster than the rest, but still leave enough set to hold the cut. So I am perplexed by your example of finding new cars that leaked off an emergency application in one minute.
If a cut leaked off the emergency application in one minute, that would mean that each car had that major defect of leakage, which further seems implausible.
I also do not understand why you are making a point about an emergency application leaking off, together with a point about the trainline leaking off. With brakes left in emergency, the trainline is 100% exhausted, so there is nothing to leak off. What would cause an emergency application to release would be the leaking off of the reservoir and brake cylinder; not a leaking off of the trainline.
However, aside from this issue of an emergency application leaking off: As I understand it, the Lac Megantic train was not left with an emergency application. It was left with a service application.
The assumption is that the shutdown of the engine and loss of air pumping caused the brakes to release from the service application. This is the point that I do not understand even though I have carefully read at least 50 explanations by people who seem to know the answer. If the compressor stopped pumping and leakage was not made up for, what leaks down? I know trainlines always have leakage, but would a leak down of the trainline with brakes in service application cause the brakes to release? I would like a simple answer to that question.
Or—was the leak-down from the cylinders holding the service application?
Another explanation was that a slight trainline pressure rise triggered a full brake release. If so, how would a loss of air pumping cause a slight trainline pressure rise?
These are the elements that I said I don’t understand when I was referencing the effect that ECP brakes would have had at Lac Megantic. But my point was that if a slight trainline pressure rise caused a full release, I suspect that this could not have occurred with ECP brakes because they are not controlled though trainline pressure. I am also not sure how ECP brakes would have been left during the tie up. And also, perhaps they will not leak down an emergency set as readily as would be the case with conventional air brakes.
However, in the very largest perspective: I am not even suggesting that ECP brakes would aid in securing a train because the rules would not allow it in the first place. Basically, overall, my response is to your point that braking improvements are worthless because you can cite a couple wrecks where braking would not have helped, despite the fact that it would help in many types of derailments. The Secretary of Transportation agrees with this point. So I predict that ECP brakes will become mandatory for oil trains.
RIDEWITHMEHENRY is the name for our almost monthly day of riding trains and transit in either the NYCity or Philadelphia areas including all commuter lines, Amtrak, subways, light rail and trolleys, bus and ferries when warranted. No fees, just let us know you want to join the ride and pay your fares. Ask to be on our email list or find us on FB as RIDEWITHMEHENRY (all caps) to get descriptions of each outing.
dehusmanIf the engines were shut down and the train line bled off then there was no air pressure in the system to apply the brakes.
.
Euclid You mention a case where brakes in emergency bled off in less than one minute. First, I am greatly surprised that it could leak off that fast.
You mention a case where brakes in emergency bled off in less than one minute. First, I am greatly surprised that it could leak off that fast.
So were we.
You must have heard compressed air leaking loudly in a major flow of leakage in order for the cylinders and reservoir to lose their pressure in one minute.
Not really if it was from multiple points and there really wasn't a huge volume of compressed air.
The point of that example was not to suggest that all cars bleed off in one minute it was that all cars leak are and eventually all will go to zero air pressure and zero braking. Some faster than others. Some have suggested an emergency application should last for weeks, the point of the story is that while there might be some cars that last for week, there are also cars that bleed off in minutes, so a person can't count on the air brake system disconnected from an air source to be a long term hold. Sooner or later the air will leak off.
I also do not understand why you are making a point about an emergency application leaking off, together with a point about the trainline leaking off. With brakes left in emergency, the trainline is 100% exhausted, so there is nothing to leak off.
Sure there is. Go read how air brakes work. When the brakes are applied (regardless of the type of application) air is vented into the cylinders, pressurizing them and pushing the piston out, which causes the brake shoes to be pushed against the wheels through a mechanical linkage. Did you catch where the air pressure is? Its in the cylinders. If there is no pressure in the reservoirs because it was vented into the cylinders and there is no pressure in the train line because the emergency application vents to atmosphere, the only place there is pressure is in the cylinders, the things keeping the brakes against the wheels. When the air leaks out of the cylinders (either back through the brake valve, through the seals on the brake rod or the brake piston), the cylinder loses pressure and brakes release.
The assumption is that the shutdown of the engine and loss of air pumping caused the brakes to release from the service application.
If the engines die, there is no source of air. Its bottled. Depending on the integrity of the train line, the air will bleed off the train depending on the quality of the gaskets in the air hoses, the quality of the joints in the train line, the quality of the seals in the brake valves and cylinders. One method of testing air brakes is the air flow method. If a train line has an air flow of less than 60 cfm of air flow in it, its considered "good". That means that a "good" train line can have leaks in it that bleed off up to 59 cfm of air. Sooner or later, with no air source, the air brakes are going to bleed off.
The more difficult option requires an understanding that air is a fluid., a compressable fluid. It is against the rules to "bottle" the air on a cut that is to set the brakes and close the angle cocks on both ends of the cut. Once the engines died the train was essentially a cut with the air bottled. Since air is a fluid its possible to get waves in it. At the wave the pressure is higher than on either side of the wave. If the engine or air compressor failed suddenly its possible that the sudden stop set up a wave going down the train line (think water hammer in water line when you shut off a faucet). If the pressure in the wave was high enough, the brake cylinder would interpret the increase in pressure as the brakes being release. Seeing the brakes being released the brake valve would dump air from the reservoir and the emergency reservoir into the train line to speed the release, that in turn would cause the next car to see a bigger increase in pressure and cause that car to release, etc. Within a few minutes most or all the cars have their brakes released.
I know trainlines always have leakage, but would a leak down of the trainline with brakes in service application cause the brakes to release? I would like a simple answer to that question.
You are asking the wrong question, its not a matter of a leak in the train line causing a release in the brakes, its can a train line NOT CONNECTED TO AN AIR SUPPLY bleed off and release. If there is no air supply at some point in time the entire brake system will leak off. The question is how long and there is no set answer for that. Could be minutes, could be a week.
However, in the very largest perspective: I am not even suggesting that ECP brakes would aid in securing a train because the rules would not allow it in the first place. Basically, overall, my response is to your point that braking improvements are worthless because you can cite a couple wrecks where braking would not have helped, despite the fact that it would help in many types of derailments.
I never said they were worthless, its just that you keep bringing them up as a solution to the CBR derailment problem. Its not that I can cite a couple wrecks where ECP braking would not have helped, its that I can't find one where it would have helped. Spending billions of dollars on a solution that doesn't solve the problem isn't a solution. If the problem is how do you keep another oil train wreck from becoming a "towering inferno", the answer is in bringing the flammable liquid cars closer to the specs of the flammable gas cars. That solution has a history and track record that is successful. It is a proven solution, its just not sexy.
dehusman If the engines die, there is no source of air. Its bottled. Depending on the integrity of the train line, the air will bleed off the train depending on the quality of the gaskets in the air hoses, the quality of the joints in the train line, the quality of the seals in the brake valves and cylinders. One method of testing air brakes is the air flow method. If a train line has an air flow of less than 60 cfm of air flow in it, its considered "good". That means that a "good" train line can have leaks in it that bleed off up to 59 cfm of air. Sooner or later, with no air source, the air brakes are going to bleed off. The more difficult option requires an understanding that air is a fluid., a compressable fluid. It is against the rules to "bottle" the air on a cut that is to set the brakes and close the angle cocks on both ends of the cut. Once the engines died the train was essentially a cut with the air bottled. Since air is a fluid its possible to get waves in it. At the wave the pressure is higher than on either side of the wave. If the engine or air compressor failed suddenly its possible that the sudden stop set up a wave going down the train line (think water hammer in water line when you shut off a faucet). If the pressure in the wave was high enough, the brake cylinder would interpret the increase in pressure as the brakes being release. Seeing the brakes being released the brake valve would dump air from the reservoir and the emergency reservoir into the train line to speed the release, that in turn would cause the next car to see a bigger increase in pressure and cause that car to release, etc. Within a few minutes most or all the cars have their brakes released.
Boy, you really don't have clue do you? I'm not sure all the King's horses and all the King's men can straighten that bunch of poppycock out!
BigJim dehusmanIf the engines were shut down and the train line bled off then there was no air pressure in the system to apply the brakes. If you believe that, you have absolutely no idea how the brake system works!
He's right Big Jim. When the brake pipe is zero there's no reduction left to initiate an emergency brake application. You can't go lower than zero. Even though the emergency portion of the reservoir is charged there's no way to actuate it.
It's an easy experiment, next time you cut away from a cut of cars don't let them dump. Instead close the angle cock, cut away and open the angle cock slowly until the brake pipe is empty.. now try getting them to go into emergency.
dehusmanIf the engines die, there is no source of air. Its bottled.
dehusmanOnce the engines died the train was essentially a cut with the air bottled.
Randy Stahl BigJim dehusmanIf the engines were shut down and the train line bled off then there was no air pressure in the system to apply the brakes. If you believe that, you have absolutely no idea how the brake system works! He's right Big Jim. When the brake pipe is zero there's no reduction left to initiate an emergency brake application. You can't go lower than zero. Even though the emergency portion of the reservoir is charged there's no way to actuate it. It's an easy experiment, next time you cut away from a cut of cars don't let them dump. Instead close the angle cock, cut away and open the angle cock slowly until the brake pipe is empty.. now try getting them to go into emergency.
No, he is not Randy.You are speaking of something entirely different. As the trainline, that was at one time charged, leaked down, the brakes applied until they reached a full service application. Period!
Here's something else I learned nearly a year ago. When the rate of the reduction of the brake pipe is very low , lets say a turbine operated EOT and normal train leakage the car brake may not apply. Lets give it 5 hours to leak to zero.
As I now see it there are THREE rates for brake reductions: Leakage rate (on a train without an air supply).
Service rate and emergency rate. As I said with a train off air or on a cut of cars with bottled air the leakage rate may not be enough to initiate a brake application.
When a locomotive on a train pumping air shuts down or dies for any reason the air will leak off. Lets say that you have a leak on the train that is slight, perhaps 30CFM. Eventually the brake pipe will leak down and the maintaining feature will keep the brake pipe charged until the brake pipe equalizes with the main reservoir. (90 psi brake pipe-90 psi main res, point of equalization). If the leakage continues the next thing to equalize are the locomotive brake cylinders (72 psi brake pipe-72 psi main res-72 psi brake cyl) If the leakage continues all three systems will leak at the same rate until there is nothing left in anything.
Once the brake pipe is exhausted there is no way to initiate any kind of brake application, certainly not even a penalty or emergency. You can't go lower than zero.
You would think that the brakes would apply with a over reduction beyond full service but that is not always the case. It depends on the rate of reduction.
I was very surprised when I did the experiment with 5 locomotives and 80 cars that the turbine operated EOT didn't cause enough leakage to set the train.
Jerry Pier A very important requirement, not noted is that an unattended triain should be placed in "Emergency" not full service. The Lake Megantic train would have sat there fro a week or more in that state without any risk of a run-away. it takes a little longer to recharge the train but that is minor factor for the removal of risk. )I wrote on this at the time of the crash but it bears repeating.)
A very important requirement, not noted is that an unattended triain should be placed in "Emergency" not full service. The Lake Megantic train would have sat there fro a week or more in that state without any risk of a run-away. it takes a little longer to recharge the train but that is minor factor for the removal of risk. )I wrote on this at the time of the crash but it bears repeating.)
Placing the train in emergency when unattended is not a US requirement. Yet.
When securing a key train, our additional requirements are for a more detailed job briefing with the dispatcher and the engineer taking the reverser out of the cab with him if we can't lock the cab doors on the lead engine. Trailing units don't need their doors locked or the cab searched for reversers that may be in the cab.
The way our job briefing check list is printed out (first part for securement of any train, second part with additional key train requirements including specific items and verbiage for the job briefing) and reads, many engineers are taking the reverser any time they can't lock the doors on any unattended train.
Railroads have agreed to limit crude oil trains to 40 mph in high threat urban areas, including a 10 mph buffer zone. On the Blair Subdivision there is a zone a few miles long that has the 40 mph for such trains. It's out in the middle of nowhere, but probably touches the 10 mile buffer zone for the Omaha metro area.
Jeff
dehusmanEuclid You mention a case where brakes in emergency bled off in less than one minute. First, I am greatly surprised that it could leak off that fast. So were we.You must have heard compressed air leaking loudly in a major flow of leakage in order for the cylinders and reservoir to lose their pressure in one minute. Not really if it was from multiple points and there really wasn't a huge volume of compressed air. I also do not understand why you are making a point about an emergency application leaking off, together with a point about the trainline leaking off. With brakes left in emergency, the trainline is 100% exhausted, so there is nothing to leak off. Sure there is. Go read how air brakes work. When the brakes are applied (regardless of the type of application) air is vented into the cylinders, pressurizing them and pushing the piston out, which causes the brake shoes to be pushed against the wheels through a mechanical linkage. Did you catch where the air pressure is? Its in the cylinders. If there is no pressure in the reservoirs because it was vented into the cylinders and there is no pressure in the train line because the emergency application vents to atmosphere, the only place there is pressure is in the cylinders, the things keeping the brakes against the wheels. When the air leaks out of the cylinders (either back through the brake valve, through the seals on the brake rod or the brake piston), the cylinder loses pressure and brakes release.
Yes, I fully understand that and have no need to go read about it. And I understand that air leaks off. I also think it is important to distinguish whether you are talking about air leaking of from the trainline or air leaking off from the cylinders and reservoirs. You seem to be going back and forth with explanations involving both types of leakage almost as though the results are the same.
For instance, you started out by saying:
“If the engines were shut down and the train line bled off then there was no air pressure in the system to apply the brakes.”
You are talking about leakage from the trainline leaking off. You say that the loss of that air would leave no air in the system to apply the brakes. I disagree. The loss of air in the trainline causes the brake valve of each car to divert its air to the cylinder, thus applying the brakes. It does not leave the system with “no air pressure to apply the brakes,” as you say it does.
But even after all this reasoning where you are telling me that the leak off of the trainline leaves no air in the system, you turn right around and lecture me about how the system still has air part of it after the trainline leaks off. Frankly, it seems like you are going out of your way to create points of disagreement for their own sake where there is nothing to disagree about.
For instance, I said:
“I also do not understand why you are making a point about an emergency application leaking off, together with a point about the trainline leaking off. With brakes left in emergency, the trainline is 100% exhausted, so there is nothing to leak off.”
When I said “there is nothing to leak off,” I meant leak off from the trainline. After all, I was responding to your point that dealt exclusively with leakage from the trainline in your quote above in blue.
So when I speak of nothing left to leak off from the trainline after an emergency application (which is true) you turn right around and bring up the air left in the reservoirs and cylinders that hold the brakes on as if this somehow refutes something I said.
You seem to be disagreeing with me, but I simply cannot pin down the point of disagreement. I believe this began when I said this in regard to my earlier comment about not knowing if ECP brakes would have prevented the MM&A runaway:
“I do not conclude that because Locomotives were shut down, ECP or not, same thing would have happened. You may be right about that, but ECP brakes are charged and controlled differently.”
I stick by that. I am simply saying I don’t know, when I said I do not conclude… I could not reach a conclusion until I knew exactly what caused the MM&A train brakes to release. You seem to be concluding that ECP brakes would not have made a difference. Yet if there was a trainline pressure wave that released the brakes, then surely ECP brakes would have prevented the release because they are not controlled by trainline pressure changes.
Randy Stahl Here's something else I learned nearly a year ago. When the rate of the reduction of the brake pipe is very low , lets say a turbine operated EOT and normal train leakage the car brake may not apply. Lets give it 5 hours to leak to zero. As I now see it there are THREE rates for brake reductions: Leakage rate (on a train without an air supply). Service rate and emergency rate. As I said with a train off air or on a cut of cars with bottled air the leakage rate may not be enough to initiate a brake application. When a locomotive on a train pumping air shuts down or dies for any reason the air will leak off. Lets say that you have a leak on the train that is slight, perhaps 30CFM. Eventually the brake pipe will leak down and the maintaining feature will keep the brake pipe charged until the brake pipe equalizes with the main reservoir. (90 psi brake pipe-90 psi main res, point of equalization). If the leakage continues the next thing to equalize are the locomotive brake cylinders (72 psi brake pipe-72 psi main res-72 psi brake cyl) If the leakage continues all three systems will leak at the same rate until there is nothing left in anything. Once the brake pipe is exhausted there is no way to initiate any kind of brake application, certainly not even a penalty or emergency. You can't go lower than zero. You would think that the brakes would apply with a over reduction beyond full service but that is not always the case. It depends on the rate of reduction. I was very surprised when I did the experiment with 5 locomotives and 80 cars that the turbine operated EOT didn't cause enough leakage to set the train.
I've had a portion of a train, say about 20 or 30 cars, can't remember the exact number, where the air turbine EOT set up the brakes after an anglecock partially turned while moving. On the other hand, I too have had about an 80 car portion where the brakes didn't set up because of the air-EOT after the train line became blocked. Amazing to watch the EOT drop by about 1 lb every few minutes while the rest of the train is in full service. That kind of situation is why the requirement for EOT's on most trains to have the capability for the engineer to place the train in emergency through the EOT.
Randy StahlYou would think that the brakes would apply with a over reduction beyond full service but that is not always the case. It depends on the rate of reduction.
That cannot happen because the aux. res. and brake cyl. have equalized. The aux.has applied all the air to the brake cyl. that it can supply. That is why it is called a full service application. Any further reduction is just wasting air from the aux. res.The only other way to apply more braking effort is to have enough air to initiate an emergency application.
Yes, I understand that but in these scenario's with depleted air and run away trains with odd tapers and gradients , an over reduction (you would think) would get the control portions moving. Agreed that with a fully charged train with a normal gradient an over-reduction is just a dangerous waste.
zugmannWhat if I need to set out a shop with air brake issues?
Then go ahead and set it out. What's the problem?
May I go back to the tragedy?
A train was left stationary, sufficiently secured....to prevent movement then.... and later an hour or so, it moved downgrade, derailed, blew up, "Oh, the tragedy of it!" Lakehurst , NJ.
The securement failed, and a lot of words here have tried to explain it.
Air brakes....I used 'em" for 42 yrs and taught 'em" at the Engine Service Training Center, SPT's.
Distilling... brake cylinder power is distributed by a device that gets commands to decrease or increase of pressure in a control pipe which diverts pressure from a storage vessel into the cylinder which controls the brake piston, rigging and brake shoes, this on each car and locomotiveThe controlling pressure pipe is satisfied....until leakage changes the state of the system..
I stipulate that hand brakes set on locomotive units and a couple of cars held the train, (here's the catch) in combination with the engine's independent. (only the locomotive's brakes) securerment existed
The independent brake was supplied straight from the air pump. If the pump was shut down by a zealous firefighter, those brakes would leak off.
Got a problem with a run-away caused catastrophe?
Were the train brakes set when the engr. got in the taxicab to go to get rest?
Euclid Then go ahead and set it out. What's the problem?
You took away the handbrakes. How am I supposed to tie it down?
zugmann EuclidThen go ahead and set it out. What's the problem?You took away the handbrakes. How am I supposed to tie it down?
EuclidThen go ahead and set it out. What's the problem?
Oh I see. I thought you thought I was leaving out the couplers. Maybe the handbrakes could be retained for that setout, but securement could just as well be accomplished by use of the single control, pneumatically powered brake lock to secure the car with air brakes set fully and mechanically locked in the set condition, just like securing a whole train.
EuclidOh I see. I thought you thought I was leaving out the couplers. Maybe the handbrakes could be retained for that setout, but securement could just as well be accomplished by use of the single control, pneumatically powered brake lock to secure the car with air brakes set fully and mechanically locked in the set condition, just like securing a whole train.
Yeah, couplers would help that, too.
Again - don't handbrakes set brakes mechanically? I'm still lost with your definitions and nuances.
I've long since come to the conclusion that the Lac Megantic train ran away because the engineer was ultimately depending on the independent to hold the train. Once the main res pressure dropped to zero, well over half of the axles on the locomotives (those not held by handbrakes) lost their brakes.
Combined with the insufficient handbrakes and the possibilities mentioned here for any service application of the entire train going away, there reached a point where there weren't enough brakes applied to hold the train.
Some sort of whole-train locking capability, perhaps to hold a full service application on the cars, probably would have prevented the incident, as long as it did not require positive air pressure to maintain that lock.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
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