Overmod ruderunner I agree that adding a spring wouldn't be complicated, pricey perhaps. A complete redesign could use the emergency reservoir to hold off the spring and if the reservoir runs out the spring would apply. A lockout mechanism for switching would be easy to add here. Before this goes too much further, we've had this discussion before, and like a whack-a-mole it seems to keep coming up when persistence of memory fades. Spring brakes were a popular invention over a century ago, along with things like the Loughridge chain brake that seem attractive until you actually try them and start to see the problems. (See John White on rubber car springs, for a different example of something that keeps cropping up and then disappearing as the technology evolves). Any spring brake powerful enough to hold a modern railroad car will be capable of causing problems if it inadvertently deploys while running. However, making it even more powerful to serve as an emergency brake is more of a disaster than those who aren't familiar with the physics are likely to know. Then there is the issue of making a mechanism that reliably pulls the spring brake off, considering how any accumulated slack in the foundation rigging was accommodated in application, while ensuring that it re-applies when safety calls ... but doesn't fail unsafe. I think it's a reasonably safe bet that such a thing would be no less hard to pull off than a current handbrake is to apply, and there is the thought looming that you'd also have to allow the spring-brake mechanism to be cinched further down into engagement for formal car securement (in other words, positive ratcheting engagement both ways). We've also discussed the 'idea' of having motor engagement and disengagement via a dedicated trainline or power plugs of some sort, which apparently is now technically feasible (although, on reflection, I think still a lunatic idea) My take on this is that for the price of the spring brake, especially a motorized or servo one, you can equip several cars with convertible ECP. And have something eventually useful.
ruderunner I agree that adding a spring wouldn't be complicated, pricey perhaps. A complete redesign could use the emergency reservoir to hold off the spring and if the reservoir runs out the spring would apply. A lockout mechanism for switching would be easy to add here.
Before this goes too much further, we've had this discussion before, and like a whack-a-mole it seems to keep coming up when persistence of memory fades.
Spring brakes were a popular invention over a century ago, along with things like the Loughridge chain brake that seem attractive until you actually try them and start to see the problems. (See John White on rubber car springs, for a different example of something that keeps cropping up and then disappearing as the technology evolves).
Any spring brake powerful enough to hold a modern railroad car will be capable of causing problems if it inadvertently deploys while running. However, making it even more powerful to serve as an emergency brake is more of a disaster than those who aren't familiar with the physics are likely to know.
Then there is the issue of making a mechanism that reliably pulls the spring brake off, considering how any accumulated slack in the foundation rigging was accommodated in application, while ensuring that it re-applies when safety calls ... but doesn't fail unsafe. I think it's a reasonably safe bet that such a thing would be no less hard to pull off than a current handbrake is to apply, and there is the thought looming that you'd also have to allow the spring-brake mechanism to be cinched further down into engagement for formal car securement (in other words, positive ratcheting engagement both ways). We've also discussed the 'idea' of having motor engagement and disengagement via a dedicated trainline or power plugs of some sort, which apparently is now technically feasible (although, on reflection, I think still a lunatic idea)
My take on this is that for the price of the spring brake, especially a motorized or servo one, you can equip several cars with convertible ECP. And have something eventually useful.
As brakes where out on trains I am sure they adjust the brakes we do the same.
The spring for our emergancy and parking brake is contained in the emergency brake chamber itself. If there is NO air pressure to overcome the spring pressure we can not move. http://www.consulab.com/products/specifications/ec12753145e.pdf
Here is how our brake chambers are arranged. We pay on average for one without the rods 80 bucks with the rods 120. They survive anything we throw at them. They handle being beat on with hammers in the winter when frozen up and if they fail they fail to the released not the applied why the springs have a pair of weak points put in that break that allow the spring to collaspe so the affected vechile can be moved to a repair shop. Time to replace is less than 30 mins normally.
ruderunnerI agree that adding a spring wouldn't be complicated, pricey perhaps. A complete redesign could use the emergency reservoir to hold off the spring and if the reservoir runs out the spring would apply. A lockout mechanism for switching would be easy to add here.
Euclid, not quite how OTR air brakes work. In those the spring applies the brakes. Air releases the brakes. No air no movement.
Going off STCO comment, I agree that adding a spring wouldn't be complicated, pricey perhaps. A complete redesign could use the emergency reservoir to hold off the spring and if the reservoir runs out the spring would apply. A lockout mechanism for switching would be easy to add here.
Modeling the Cleveland and Pittsburgh during the PennCentral era starting on the Cleveland lakefront and ending in Mingo junction
Shadow the Cats owner Euclid Shadow the Cats owner If it comes out that they pissed away their air then look for regulators to say we need to find a way to stop this from happening again. Train brakes work fine as long as they have AIR Pressure. However you lose the air pressure and your screwed. La Magnetic now here in the USA. The railroads are going to have to accept that the continued loss of life is unacceptable in today's society. God forbid a train did the same thing on Cajon Pass again it has happened multiple times in the past. It is time to come up with a failsafe emergency braking system for these things. Not one that if the air pressure is gone won't work one that has a mechanical backup so even if every pound of air is gone it will work. When yarding a train I understand your industry dumps all the air out of the system. When they pull the bleeder rod that could act as the catch for the spring brake to prevent the parking brakes from coming on during the switching process. What's it going to take a full tanker car full of pressurized Cholrine gas being ruptured in another derailment from a train losing air pressure for railroads to see their brakes are not up to what is needed with todays monsters. The prevention of peeing away the air is provided by ECP brakes. I don't quite follow what you are saying about the bleeder rod, spring brake catch, etc. There need not be a mechanical spring brake to achieve the fail safe element that you mention. Even with ECP if that fails the brakes fail back to normal airbrake functions. With a spring brake used for even emergency situations only if the brake pipeline pressure gets below a certain point then the spring overcomes the air and applies the brakes. In OTR trailers and tractors they're set to apply at 40 psi our low air warning kicks on at 60 psi. They've been mandated here for 40 year's since the 121 airbrake regulations came out.
Euclid Shadow the Cats owner If it comes out that they pissed away their air then look for regulators to say we need to find a way to stop this from happening again. Train brakes work fine as long as they have AIR Pressure. However you lose the air pressure and your screwed. La Magnetic now here in the USA. The railroads are going to have to accept that the continued loss of life is unacceptable in today's society. God forbid a train did the same thing on Cajon Pass again it has happened multiple times in the past. It is time to come up with a failsafe emergency braking system for these things. Not one that if the air pressure is gone won't work one that has a mechanical backup so even if every pound of air is gone it will work. When yarding a train I understand your industry dumps all the air out of the system. When they pull the bleeder rod that could act as the catch for the spring brake to prevent the parking brakes from coming on during the switching process. What's it going to take a full tanker car full of pressurized Cholrine gas being ruptured in another derailment from a train losing air pressure for railroads to see their brakes are not up to what is needed with todays monsters. The prevention of peeing away the air is provided by ECP brakes. I don't quite follow what you are saying about the bleeder rod, spring brake catch, etc. There need not be a mechanical spring brake to achieve the fail safe element that you mention.
Shadow the Cats owner If it comes out that they pissed away their air then look for regulators to say we need to find a way to stop this from happening again. Train brakes work fine as long as they have AIR Pressure. However you lose the air pressure and your screwed. La Magnetic now here in the USA. The railroads are going to have to accept that the continued loss of life is unacceptable in today's society. God forbid a train did the same thing on Cajon Pass again it has happened multiple times in the past. It is time to come up with a failsafe emergency braking system for these things. Not one that if the air pressure is gone won't work one that has a mechanical backup so even if every pound of air is gone it will work. When yarding a train I understand your industry dumps all the air out of the system. When they pull the bleeder rod that could act as the catch for the spring brake to prevent the parking brakes from coming on during the switching process. What's it going to take a full tanker car full of pressurized Cholrine gas being ruptured in another derailment from a train losing air pressure for railroads to see their brakes are not up to what is needed with todays monsters.
If it comes out that they pissed away their air then look for regulators to say we need to find a way to stop this from happening again. Train brakes work fine as long as they have AIR Pressure. However you lose the air pressure and your screwed. La Magnetic now here in the USA. The railroads are going to have to accept that the continued loss of life is unacceptable in today's society. God forbid a train did the same thing on Cajon Pass again it has happened multiple times in the past. It is time to come up with a failsafe emergency braking system for these things. Not one that if the air pressure is gone won't work one that has a mechanical backup so even if every pound of air is gone it will work. When yarding a train I understand your industry dumps all the air out of the system. When they pull the bleeder rod that could act as the catch for the spring brake to prevent the parking brakes from coming on during the switching process. What's it going to take a full tanker car full of pressurized Cholrine gas being ruptured in another derailment from a train losing air pressure for railroads to see their brakes are not up to what is needed with todays monsters.
The prevention of peeing away the air is provided by ECP brakes.
I don't quite follow what you are saying about the bleeder rod, spring brake catch, etc. There need not be a mechanical spring brake to achieve the fail safe element that you mention.
Even with ECP if that fails the brakes fail back to normal airbrake functions. With a spring brake used for even emergency situations only if the brake pipeline pressure gets below a certain point then the spring overcomes the air and applies the brakes. In OTR trailers and tractors they're set to apply at 40 psi our low air warning kicks on at 60 psi. They've been mandated here for 40 year's since the 121 airbrake regulations came out.
So, if I understand you, the trucking industry uses straight air brakes with the use of stored spring force to provide a backup brake activation in case there is a loss of the air pressure normally used for braking.
Train air brakes are not a straight air system. They have their own version of failsafe backup. I do not think the train brake system would readily translate into the spring backup used by the trucking industry. The main element that needs backup is the pressurized air delivery line of a straight air brake system. Train brakes originated as a straight air brake system, but they found they needed a backup in case the train broke in two, which was very common and still is.
When this need for backup system for train braking became obvious, they could have added springs to the cylinders and switched functions around so that the straight air caused the cylinders to release the brakes by overcoming the spring pressure. But they also needed to use the brakes for gradual stopping and not just for emergencies. For gradual stopping, braking force must be modulated, and the spring application would need additional complex mechanism to achieve and control brake force modulation.
So the railroads adopted a novel appoach of using the train line to deliver air to a working brake system on each car with its own reservoir to store the air needed to power that independent brake system on each car. Once the train line nourished all the reservoirs with air to power their individual brake systems on each car, the train line was transformed into a pneumatic control line to tell the car reservoirs when to use their air to set the brakes. The pressure of the control train line was reduced in order to cause this application of the car reservoir air to power the brake cylinders on each car.
That fundamental principle meant that if a train broke in two and parted its pressureized train line, it would cause an application of the train brakes rather than render the train brakes inoperative as would be the case with a straight air brake system and its pressurized train line.
Also, if ECP brakes do fail, they do not revert back to air brake functions of the conventional train air brake system, as you say. ECP brakes can fail in various way, but not in the manner of peeing away the air like can happen with conventional train air brakes.
rdamon One could only imagine how crowded the beaches would be as well!! Daytona is already a mess in March/April.
One could only imagine how crowded the beaches would be as well!! Daytona is already a mess in March/April.
Can't wait for the “Cars Gone Wild” DVD ads to start on late night TV.
GROAN!
Semper Vaporo
Pkgs.
rdamonOne could only imagine how crowded the beaches would be as well!! Daytona is already a mess in March/April.
Well played.
Shadow the Cats ownerFor switching it wouldn't be hard especially for yard movements or even moving them at a customer to install a rod that overrode the spring brake when pulled. You already pull a bleeder valve to dump the air out of the tanks now when a train comes into a yard to switch. Put the new one in the same area but it captures the spring brake before the air is dumped out. A good mechaincal engineer could desgn this system in a hurry to work as needed for switching and do as needed in an emergency while applying the KISS principle.
Retrofitting hundreds of thousands of rail cars to 'have' a spring brake would be far from KISS. Not to mention costly!
Never too old to have a happy childhood!
Shadow the Cats ownerFor switching it wouldn't be hard especially for yard movements or even moving them at a customer to install a rod that overrode the spring brake when pulled.
Railcars don't have anything called a "spring brake".
Dave H. Painted side goes up. My website : wnbranch.com
tree68 Paul of Covington How much do we know so far about the cause of this accident? We're discussing everything in the world based on what? I'm still waiting for us to get around to "situational awareness." I think that was briefly touched on with a comment about a possible missed signal. I'd have to scour the whole thread. We've gotten a few snippets, but as you say, nothing to give us a firm idea of what did happen.
Paul of Covington How much do we know so far about the cause of this accident? We're discussing everything in the world based on what? I'm still waiting for us to get around to "situational awareness."
How much do we know so far about the cause of this accident? We're discussing everything in the world based on what? I'm still waiting for us to get around to "situational awareness."
I think that was briefly touched on with a comment about a possible missed signal. I'd have to scour the whole thread.
We've gotten a few snippets, but as you say, nothing to give us a firm idea of what did happen.
It may be months before a preliminary NTSB report is released, but seems likely the cause will be either a signal malfunction or a human error by the crew of the moving train.
Roadrailers had spring-type brakes. When there was a problem it would tie up the railroad until the service truck could come out.
Yeah, when air is urniated away it can cause runaways. But locked brakes on a car can cause derailments pretty quickly, too. THis may be a case of a cure worse than a disease. Never minding the whole fact that you are changing one of the core elements of a railcar.
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
For switching it wouldn't be hard especially for yard movements or even moving them at a customer to install a rod that overrode the spring brake when pulled. You already pull a bleeder valve to dump the air out of the tanks now when a train comes into a yard to switch. Put the new one in the same area but it captures the spring brake before the air is dumped out. A good mechaincal engineer could desgn this system in a hurry to work as needed for switching and do as needed in an emergency while applying the KISS principle.
Other than it being some kind of braking issue, not much has leaked out. FWIW, someone on another site said the rumor going around his area was that the crew did nothing wrong. This person also pointed out it was close to a spot where a closed anglecock led to a similar collision in 1979. In that one, the crew on the caboose didn't open the emergency valve.
IMO, they have a good idea of what went wrong. They aren't going to say much until they can find a way to place as much blame as possible on the crew. It's been done before where the crew lived. Should be that much easier when the crew didn't. I won't be surprised if the images from the inward facing camera aren't retrievable.
Jeff
Shadow the Cats owner In OTR trailers and tractors they're set to apply at 40 psi our low air warning kicks on at 60 psi. They've been mandated here for 40 year's since the 121 airbrake regulations came out.
In OTR trailers and tractors they're set to apply at 40 psi our low air warning kicks on at 60 psi. They've been mandated here for 40 year's since the 121 airbrake regulations came out.
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...
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
SD70Dude jeffhergert It looks like the area where it happened is on a mostly 1.5 % grade. One report I was shown by a coworker said the train picked up cars (I think in Laramie WY) and was 12000 tons. One of the engines involved was a SD70m, but unknown when I was shown this info last week was if it was leading. They have a mechanical brake valve, either a 26L or the desk top equivalent, and lately some have been having pressure maintaining issues. They can have other defects where they don't work properly, but as someone has observed - you always have the "big Hole" as a last resort. Assuming the brake pressure hasn't dropped below about 45 or 50 psi. Below that pressure, emergency may not be transmitted through the brake pipe. Passenger equipment will automatically dump when pressure drops below 20 psi as a fail safe last resort. Freight equipment doesn't have that feature. Jeff Do the automatic brake valves on UP power have "freight" and "passenger" positions, or do you only have "in" and "out"? In my experience changing the automatic mode from "freight" to "passenger" (with the automatic released of course) usually makes the unit pressure maintain properly. Nearly all of CN's units with 26 and 30 type brake valves (except the ex-Oakway SD60's) have all 3 positions. We discussed this problem in another thread not so long ago, and I think it was Big Jim who said that a leaky gasket somewhere inside the control stand is the most common cause of that problem.
jeffhergert It looks like the area where it happened is on a mostly 1.5 % grade. One report I was shown by a coworker said the train picked up cars (I think in Laramie WY) and was 12000 tons. One of the engines involved was a SD70m, but unknown when I was shown this info last week was if it was leading. They have a mechanical brake valve, either a 26L or the desk top equivalent, and lately some have been having pressure maintaining issues. They can have other defects where they don't work properly, but as someone has observed - you always have the "big Hole" as a last resort. Assuming the brake pressure hasn't dropped below about 45 or 50 psi. Below that pressure, emergency may not be transmitted through the brake pipe. Passenger equipment will automatically dump when pressure drops below 20 psi as a fail safe last resort. Freight equipment doesn't have that feature. Jeff
It looks like the area where it happened is on a mostly 1.5 % grade. One report I was shown by a coworker said the train picked up cars (I think in Laramie WY) and was 12000 tons.
One of the engines involved was a SD70m, but unknown when I was shown this info last week was if it was leading. They have a mechanical brake valve, either a 26L or the desk top equivalent, and lately some have been having pressure maintaining issues. They can have other defects where they don't work properly, but as someone has observed - you always have the "big Hole" as a last resort. Assuming the brake pressure hasn't dropped below about 45 or 50 psi. Below that pressure, emergency may not be transmitted through the brake pipe. Passenger equipment will automatically dump when pressure drops below 20 psi as a fail safe last resort. Freight equipment doesn't have that feature.
Do the automatic brake valves on UP power have "freight" and "passenger" positions, or do you only have "in" and "out"?
In my experience changing the automatic mode from "freight" to "passenger" (with the automatic released of course) usually makes the unit pressure maintain properly. Nearly all of CN's units with 26 and 30 type brake valves (except the ex-Oakway SD60's) have all 3 positions.
We discussed this problem in another thread not so long ago, and I think it was Big Jim who said that a leaky gasket somewhere inside the control stand is the most common cause of that problem.
The SD70m engines and I think all, like the CN, with 26 or 30 type valves have freight and passenger positions. I've used passenger before because of a leaking equalizing reservoir, but many don't know about doing that. At times they seem to not want engineers running in passenger, because of the chance of accidently releasing the brake because the handle is accidently moved. Other times you'll be told to do that. I've only seen one training video that mentioned placing it in passenger, and that was after 13 years as an engineer. (I already knew about doing that, even before I went into engine service.) The engines with the brake valves cut in through the computer screens only have in/lead or out/trail options.
tree68 SD70Dude Cycle braking too many times can indeed achieve the same end result as Lac-Megantic, but so far all we have here is rumours, no hard facts yet. I believe a grade was mentioned, and that this was reported as a runaway. Cycle braking (and thus pssng away one's air) has been a factor in a number of runaways. Another possibility for the list.
SD70Dude Cycle braking too many times can indeed achieve the same end result as Lac-Megantic, but so far all we have here is rumours, no hard facts yet.
I believe a grade was mentioned, and that this was reported as a runaway. Cycle braking (and thus pssng away one's air) has been a factor in a number of runaways. Another possibility for the list.
Johnny
SD70Dude Euclid SD70Dude The procedure they are describing is known as venting a train, and as long as the reduction rate exceeds 3 PSI per minute it will result in a full service brake application on the train, and a brake pipe pressure of 0 PSI. The purpose of that procedure is to not put the train in emergency in order to save the air in the cars' Did you mean to say, "as long as the reduction rate does not exceed 3 PSI per minute..."? My understanding of drawing off air slowly to avoid triggering an emergency application is that the rate of reduction has to be under a certain amount. The 3 PSI per minute reduction rate is required needed to trigger a car control valve to direct air from the auxiliary reservoir to the brake cylinder. A slower reduction/leakage rate may not result in any air brake application, as happened at Lac-Megantic. The whole point of venting a train is to leave the air brakes applied (but not in emergency) and the angle cock fully open. In my experience fully opening a angle cock when venting a train takes around a minute (actual results may vary depending on train length and how heavy a brake was already set on the train). I can't remember offhand what the necessary reduction rate to trigger an emergency application is, but it is quite high.
Euclid SD70Dude The procedure they are describing is known as venting a train, and as long as the reduction rate exceeds 3 PSI per minute it will result in a full service brake application on the train, and a brake pipe pressure of 0 PSI. The purpose of that procedure is to not put the train in emergency in order to save the air in the cars' Did you mean to say, "as long as the reduction rate does not exceed 3 PSI per minute..."? My understanding of drawing off air slowly to avoid triggering an emergency application is that the rate of reduction has to be under a certain amount.
SD70Dude The procedure they are describing is known as venting a train, and as long as the reduction rate exceeds 3 PSI per minute it will result in a full service brake application on the train, and a brake pipe pressure of 0 PSI. The purpose of that procedure is to not put the train in emergency in order to save the air in the cars'
Did you mean to say, "as long as the reduction rate does not exceed 3 PSI per minute..."? My understanding of drawing off air slowly to avoid triggering an emergency application is that the rate of reduction has to be under a certain amount.
The 3 PSI per minute reduction rate is required needed to trigger a car control valve to direct air from the auxiliary reservoir to the brake cylinder. A slower reduction/leakage rate may not result in any air brake application, as happened at Lac-Megantic.
The whole point of venting a train is to leave the air brakes applied (but not in emergency) and the angle cock fully open.
In my experience fully opening a angle cock when venting a train takes around a minute (actual results may vary depending on train length and how heavy a brake was already set on the train).
I can't remember offhand what the necessary reduction rate to trigger an emergency application is, but it is quite high.
Greetings from Alberta
-an Articulate Malcontent
BigJim SD70Dude We discussed this problem in another thread not so long ago, and I think it was Big Jim who said that a leaky gasket somewhere inside the control stand is the most common cause of that problem. What I think you are referring to is when I said that a small gasket on the back of the equalizing reservoir gauge, if damaged, can cause a leak on the equalizing reservoir side, so, that when the brake application is made, the pressure keeps leaking down on the equalizing reservoir causing the brakes to keep being applied relative to the amount of leakage.
SD70Dude We discussed this problem in another thread not so long ago, and I think it was Big Jim who said that a leaky gasket somewhere inside the control stand is the most common cause of that problem.
What I think you are referring to is when I said that a small gasket on the back of the equalizing reservoir gauge, if damaged, can cause a leak on the equalizing reservoir side, so, that when the brake application is made, the pressure keeps leaking down on the equalizing reservoir causing the brakes to keep being applied relative to the amount of leakage.
Yes that's what I was thinking of.
SD70DudeWe discussed this problem in another thread not so long ago, and I think it was Big Jim who said that a leaky gasket somewhere inside the control stand is the most common cause of that problem.
.
SD70DudeThe procedure they are describing is known as venting a train, and as long as the reduction rate exceeds 3 PSI per minute it will result in a full service brake application on the train, and a brake pipe pressure of 0 PSI. The purpose of that procedure is to not put the train in emergency in order to save the air in the cars'
SD70DudeCycle braking too many times can indeed achieve the same end result as Lac-Megantic, but so far all we have here is rumours, no hard facts yet.
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