Euclid The 2006 FRA report on ECP brakes says that ECP can totally eliminate the need for power braking due to the benefit of graduated release. It seems to me that ECP has many advantages over current practice, but the railroads do not believe the benefits are worth the enormous cost of a universal conversion.
Extended range dynamic braking on today's locomotives has virtually ended the need for air brakes, except for the final stop. Dynamic Braking power can be increased and decreased as necessary by the engineer - dynamic braking does not put thremal stress on any wheels - engine or cars. Air brakes put thermal stresses on the wheels of the cars (engine brakes are normally bailed off). ECP increases wheel stress if it were to be used in place of Dynamics.
M636CExcept for Fortescue Metals, every other operator with ECP braking has a mixed fleet of ECP and non-ECP cars and they cope with it. In Queensland, Pacific National use the same type of locomotive on conventional brake intermodal trains and ECP brake coal trains. The older intermodal locomotives can't be used on coal trains, but the coal locomotives can and do haul intermodal trains with conventional brakes.
Can you give specific detail on the equipment and procedures that are used to provide this 'dual-mode' braking capability?
A conversion of all the freight cars in the USA to ECP would be expensive and may never happen. But the conversion of unit trains carrying oil or coal or iron ore is practical and not that expensive. A staged conversion, as presumably occurred with the change to Westinghouse brakes or the change from link and pin to Janney knuckle couplers is what will have to happen. Some locomotives and some freight cars might be fitted with a through cable to allow the ECP signal to pass through a non ECP vehicle.
As I understand it, a passthrough cable won't make non-ECP cars capable of service-brake compatibility with ECP-converted cars when running under ECP. The one-pipe conversion changes the single brake line to run at main-reservoir pressure all the time, and this precludes any conventional control of the triple valve via pressure differential (although the emergency can still be modulated via air signal in the now-high-pressure air in this hose.)
Where does it help to have wireline continuity (with 230V and required connector signal integrity) throughout the train vs. expanding the existing radio channels now used for DPU? Sure, there are advantages for things like LOS in cuts or tunnels, but those are much more readily addressed with the equivalent of femtocells in phone coverage, aren't they?
I think one Australian operator has vehicles that can be manually changed from ECP to Westinghouse and back. This will cost more but provides ultimate flexibility.
It was my understanding from looking at the WABTEC presentation that the 'adapter' version of the ECP valve was installed directly in line with existing brake equipment (I can find the exact 'slide' number that shows this). It stands to reason that such a car would continue to work with 'conventional' effectiveness with the ECP unpowered/unsignalled (I would expect the ECP valve to default to 'passthrough') but it would appear to follow, again, that the conventional brake gear would actuate in an undesired fashion during ECP operation if the trainline pressure were allowed to fluctuate. This would self-correct when the trainline came back up to pressure, of course, but for some period of time you would have an unpredictable number of cars, in unpredictable positions, with lagging and not graduated release ... without, as far as I know, any indication on the ECP network as to which of them were doing so.
If the point about rapid re-acceleration after brake release is as significant as you indicate -- and I think that it is -- I see a number of alarming implications that have not, so far, been addressed by the ECP promoters in the United States so far.
I don't have any specific information on how dual mode freight cars are set up.
It would appear to be easy to incorporate a slide to cut off the conventional valve from the "adapter" version of the ECP valve. I think the SSR coal hoppers that appear to work in both modes have this type of ECP valve, but I don't know how the changeover occurs.
In the case of locomotives of course, all ECP locomotives can operate conventional trains without modification, so there is no problem.
A "through cabled" non ECP locomotive can run in an MU consist hauling an ECP train because the locomotives still operate with conventional independent air brakes.
When talking about "through cabled" freight cars, I was assuming that these would run as unbraked vehicles in ECP trains, just as "through piped" unbraked vehicles ran in British vacuum braked trains in the 1930s to 1960s. There was a limit to the number of unbraked cars that could be run if the train was to be treated as a braked rather than unbraked train.
There appears to be no problem with cars from ECP unit trains running in conventional trains because that just doesn't arise. ECP cars have an emulation mode using battery power for short transfer runs, but most operators just move such vehicles with ECP equipped units from yards to maintenance shops.
I'm not trying to promote the use of ECP brakes.
I'm just trying to understand why a system that has been accepted and used in one country is being resisted in another.
I do know a lot about the forces involved in train action, since I spent some years measuring them for Hamersley Iron in Western Australia. My experience suggests that rapid simultaneous brake application could solve a lot of problems. Not all of them, but a lot.
One of the trains I was testing made an emergency stop when the yard controller reversed a signal to red without realising how close we were. The 220 car train broke in five places, one break being a drawbar that pulled out of a married pair of cars when the yoke broke, the remainder being at couplers where knuckles broke.
If that train had used ECP brakes, it would probably have stopped with no damage.
I have earlier in this thread mentioned three devastating derailments caused by loss of Locotrol signal at critical points on the Goonyella system. I'm sure Pacific National are pleased that their trains run MU though the ECP cable every time thay pass that section of line with four locos, two at the one and two thirds points and one each end.
There was a derailment that I believe was due to misuse of the ECP brake system. An ECP train was leaving a mine and what I think happened is as follows: expecting the signal to clear, the driver decided to release the train brake and hold the train on a slight downgrade on the independent on the three locomotives. I assume the crew had done this before with conventional trains. However, the quick release of the ECP system compared to the gradual release of a conventional brake immediately threw the whole train weight on the locomotives and all three units were pushed through the catchpoints. This never happened again...
As I've said earlier, there don't appear to be any real disadvantages to ECP operation and unit trains are gradually being converted to ECP. I expect that intermodal trains will be next, because although these aren't heavy, they are long and this affects the operation of conventional Westinghouse brakes.
In the USA, there appears to be a search for reasons why ECP won't work, rather than just adopting it. The Australian companies adopted ECP because they think it saves money, and nobody is changing back...
M636C
It's my understanding that dual mode ECP equipment only works in one mode at a time. A train is either in one mode or the other. If the car is in an ECP unit train, it's operated in ECP mode. If the car is in a general freight (with other equipment not equipped for ECP) it's operated in conventional mode. There is no provision to operate "half and half" so to speak.
I'm not against ECP. I think it would make my job a bit easier, provided it could be used properly. I'm just able to see the railroad's current point of view. I'm sure if the railroads could completely eliminate all "loose car/car load" operations and go to strictly unit style trains, they would be more willing to embrace ECP.
Jeff
How would ECP or multiple end of train devices help prevent stringlining which is a major problem on mountian grades?
caldreamer How would ECP or multiple end of train devices help prevent stringlining which is a major problem on mountian grades?
End of train devices do not make service brake applications. The only brake command they are currently capable of is to dump the air when initiated by the engineer.
The idea behind the original post about using multiple ETD for what I perceive as normal braking operation isn't possible with the current equipment. You would need to redesign the ETDs to do that.
Multiple DPUs within a train is already possible and would give the same benefit as "multiple ETD/MTDs" throughout the train. The only drawback with DPs through out a Hazmat train is the need for buffer cars on each side of each mid-train DP.
M636CIn the USA, there appears to be a search for reasons why ECP won't work, rather than just adopting it. The Australian companies adopted ECP because they think it saves money, and nobody is changing back...
Given that and Euclid's post on a Canadian railroad's favorable (saves money immediately) experience with ECP, resistance here seems to be coming from a short-sighted, uninformed bean-counter perspective and "the search for reasons why ECP won't work" is more of a search for excuses to not adopt (along with objection to any government mandates). The history of adoption of safety improvements by US rails shows resistance to voluntary adoption going back to the Janney coupler.
C&NW, CA&E, MILW, CGW and IC fan
It seems to me the railroads that have converted to ECP are mostly those that operate bulk commodity/unit train operations, if not outright captive equipment. The business argument for them is probably easier to make.
It reminds me of those times when someone brings up some new idea, like the cargo-sprinters, etc. Many of them would be possible, IF you were starting from scratch or had an entirely captive system, like in some countries where the rail system hasn't been developed to a large extent. It's when trying to impose something "new" on an existing system that things won't always easily mesh. Those supporting the idea/equipment think the only reason it's not adopted is because those in the industry are "dinosaur/stuck in the mud/luddites" who just can't see the light.
It also seems the most vocal boosters are those who either have skin in the game (vendors) or not much real world experience in how things work.
Some form of ECP and/or PTC is used on many railroads in the world.
jeffhergert caldreamer How would ECP or multiple end of train devices help prevent stringlining which is a major problem on mountian grades? End of train devices do not make service brake applications. The only brake command they are currently capable of is to dump the air when initiated by the engineer. The idea behind the original post about using multiple ETD for what I perceive as normal braking operation isn't possible with the current equipment. You would need to redesign the ETDs to do that. Multiple DPUs within a train is already possible and would give the same benefit as "multiple ETD/MTDs" throughout the train. The only drawback with DPs through out a Hazmat train is the need for buffer cars on each side of each mid-train DP. Jeff
How does the redesigned ETD/MTD release the brake application?
VEry good question. Obvioiusly, now that I have given this some thought, anything from a gentle application to full service to full emergency is possible, just how much of an opening from the train line air pipe to the air, but charging requires acess to air under pressure, and that the EOTD just doesn not have. So my idea gives only half electronic brake control, good for brake application, but the release must come the conventional way.
One the other hand, the freighcar equipped for electronic brake control has an oversize air tank with sufficient capacity for several applications and releases, and it can be used to assist in recharging the air line for release.
Still might be worthwhile, though.
daveklepper VEry good question. Obvioiusly, now that I have given this some thought, anything from a gentle application to full service to full emergency is possible, just how much of an opening from the train line air pipe to the air, but charging requires acess to air under pressure, and that the EOTD just doesn not have. So my idea gives only half electronic brake control, good for brake application, but the release must come the conventional way. One the other hand, the freighcar equipped for electronic brake control has an oversize air tank with sufficient capacity for several applications and releases, and it can be used to assist in recharging the air line for release. Still might be worthwhile, though.
Who says the cars have oversized air reseviors?
Never too old to have a happy childhood!
if they don't, if the car's airtank is big enough only for one brake application, then how would ANY EPC provide instantaneous release of brakes?
You are right. They don't have the oversize tanks now. But I assume they get them with onboard car EPC installation.
Normal WEstinghouse: Emergency: the car's air tank is almost emtied to apply full braking pressure on the brake cylinders. Release charges the train line and fills the airtanks in each car at the same time. EPC requires larger airtanks.
With ECP, the car's auxilary reservoir can be used to make and release brake applications more often because it is always being charged. (Note. Conventional air brakes can make more than one application without being fully recharged, but there is a limit. Too many sets and releases too close together and eventually you don't have brakes.) Even during and while maintaining a brake application. That's because the train line can be kept at a constant pressure since it's no longer being used to "signal" the control valves to set or release the brakes.
Current air brakes, it's only being charged in the release/running position. During an application and when the control valve goes to "lap" (both sides, reservoir and trainline, at equal pressure) to maintain the application, the reservoir is cut off from the air supply. It's the pressure differences between the train line and reservoir that signal the control valve to operate.
daveklepperNormal WEstinghouse: Emergency: the car's air tank is almost emtied
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jeffhergert It's my understanding that dual mode ECP equipment only works in one mode at a time. A train is either in one mode or the other. If the car is in an ECP unit train, it's operated in ECP mode. If the car is in a general freight (with other equipment not equipped for ECP) it's operated in conventional mode. There is no provision to operate "half and half" so to speak.
It may be at the engineer's discretion, on an all-ECP train. But if there is a non-ECP car or cars in the consist it has to be operated in conventional mode. Perhaps somebody here knows exactly how an non-ECP car would behave (and affect the rest of the train) in ECP mode. With one method the car depends on electronic signals for brake application and release, the other train line air pressure. The two are not particularly compatible.
daveklepperNormal Westinghouse: Emergency: the car's air tank is almost emtied to apply full braking pressure on the brake cylinders.
Read this and reconsider...
One word sums it up: equalization.
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...
cx500 It may be at the engineer's discretion, on an all-ECP train. But if there is a non-ECP car or cars in the consist it has to be operated in conventional mode. Perhaps somebody here knows exactly how an non-ECP car would behave (and affect the rest of the train) in ECP mode. With one method the car depends on electronic signals for brake application and release, the other train line air pressure. The two are not particularly compatible.
I think the systems are much less compatible than you suggest.
ECP cars can operate in "emulation mode" on battery power in a non ECP train, to be moved from a yard to a workshop, for example, but the battery will only last for a couple of hours.
Non ECP cars can't be coupled into an ECP train at all.
I mentioned earlier about adding a through cable to a non ECP car to allow it to be run in an ECP train, but it would have no brake capability in such a train. A limited number of cars with brakes isolated are presumably allowed now and the same restrictions would apply.
The non-compatibility is presumably the main objection to ECP, but I believe that unit trains could be converted, as has been done in Australia and elsewhere with less disruption than the opponents imagine.
M636C cx500 It may be at the engineer's discretion, on an all-ECP train. But if there is a non-ECP car or cars in the consist it has to be operated in conventional mode. Perhaps somebody here knows exactly how an non-ECP car would behave (and affect the rest of the train) in ECP mode. With one method the car depends on electronic signals for brake application and release, the other train line air pressure. The two are not particularly compatible. I think the systems are much less compatible than you suggest. ECP cars can operate in "emulation mode" on battery power in a non ECP train, to be moved from a yard to a workshop, for example, but the battery will only last for a couple of hours. Non ECP cars can't be coupled into an ECP train at all. I mentioned earlier about adding a through cable to a non ECP car to allow it to be run in an ECP train, but it would have no brake capability in such a train. A limited number of cars with brakes isolated are presumably allowed now and the same restrictions would apply. The non-compatibility is presumably the main objection to ECP, but I believe that unit trains could be converted, as has been done in Australia and elsewhere with less disruption than the opponents imagine. M636C
In day in, day out operations in the US Unit Trains, are not as 'unitized' as those outside the railroad industry would like to think. Cars get shopped on line of road and enter the 'loose car' network to get to either destination or origin depending on their loaded or empty status. At origin and/or destination the trains are inspected and there are routinely cars that are shopped and must be set out of the trains for repairs. Cars that are set out will take several days to several weeks for their required repairs - the 'unit trains' will not be held for these cars to be repaired, other cars will be added to handle the required commodity volume for the trains.
When it comes to ECP, locomotives also have to equipped. Locomotive break down on line of road. Without 'all' locomotives being ECP equipped, special ECP locomotives would be necessary to replace the broken down engine. In today's operations (at least on my carrier) there is very little if any 'extra power' running on trains that can be given up to a train that has broken down power. It is not that uncommon for a train to be delayed 24 hours or more waiting on power to replace broken down power and that is without needing specially equipped ECP locomotives.
Anything can be done for a price, how much are you willing to spend.
jeffhergert How does the redesigned ETD/MTD release the brake application? Jeff
Would this work? To apply the brakes you have signaled the ETD and MTD's to bleed the air down to a certain level. To release them you signal them to close the valves then increase the air pressure from the locomotive. As the pipe pressure increases, the brakes will release. With the valves closed, you are back in "Westinghouse mode."
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"A stranger's just a friend you ain't met yet." --- Dave Gardner
BaltACD In day in, day out operations in the US Unit Trains, are not as 'unitized' as those outside the railroad industry would like to think. Cars get shopped on line of road and enter the 'loose car' network to get to either destination or origin depending on their loaded or empty status. At origin and/or destination the trains are inspected and there are routinely cars that are shopped and must be set out of the trains for repairs. Cars that are set out will take several days to several weeks for their required repairs - the 'unit trains' will not be held for these cars to be repaired, other cars will be added to handle the required commodity volume for the trains. When it comes to ECP, locomotives also have to equipped. Locomotive break down on line of road. Without 'all' locomotives being ECP equipped, special ECP locomotives would be necessary to replace the broken down engine. In today's operations (at least on my carrier) there is very little if any 'extra power' running on trains that can be given up to a train that has broken down power. It is not that uncommon for a train to be delayed 24 hours or more waiting on power to replace broken down power and that is without needing specially equipped ECP locomotives. Anything can be done for a price, how much are you willing to spend.
Paul of Covington jeffhergert How does the redesigned ETD/MTD release the brake application? Jeff Would this work? To apply the brakes you have signaled the ETD and MTD's to bleed the air down to a certain level. To release them you signal them to close the valves then increase the air pressure from the locomotive. As the pipe pressure increases, the brakes will release. With the valves closed, you are back in "Westinghouse mode."
No functional improvement in the 'problem' that was being discussed. You would need air admission from a high-pressure source at each of the MTD valve locations to get the higher-speed release, and this would either require a separate high-pressure trainline from the locomotive(s) or an independent source of air like a compressor at each point. The cost of either alternative more or less utterly defeats the purpose of using multiple MTDs instead of a full ECP conversion.
There are a couple of approaches that get around this, but none I know of are suitable for use except in critical situations.
Wh would not one large oversize air-tank, usually at maximum train-line pressure, on each car, take the place of a compressor on each car? If the capacity of the tank was ten times that required for a full emergency application, 1/10th of its air going to the brake cylinders for the emergency application, would not the 90% remaining be sufficient to provide for a release?
If not, what ratio would be required? After the full release, the train line restores the full pressure, of course.
Wizlish Paul of Covington jeffhergert How does the redesigned ETD/MTD release the brake application? Jeff Would this work? To apply the brakes you have signaled the ETD and MTD's to bleed the air down to a certain level. To release them you signal them to close the valves then increase the air pressure from the locomotive. As the pipe pressure increases, the brakes will release. With the valves closed, you are back in "Westinghouse mode." No functional improvement in the 'problem' that was being discussed. You would need air admission from a high-pressure source at each of the MTD valve locations to get the higher-speed release, and this would either require a separate high-pressure trainline from the locomotive(s) or an independent source of air like a compressor at each point. The cost of either alternative more or less utterly defeats the purpose of using multiple MTDs instead of a full ECP conversion. There are a couple of approaches that get around this, but none I know of are suitable for use except in critical situations.
I've been mulling this over thinking that there was something I didn't understand about the way brakes work, and while I'm sure there's a lot I don't understand, I think in this case I need to clarify something: the MTD's bleed the trainline down to the desired set, and the same is done at the locomotive. To release the brakes, the MTD's close off their bleed valves and the pressure is pumped up from the locomotive just as in normal Westinghouse mode. True, you would not get a high-speed release; the only advantage would be the faster set.
I had been thinking about this use of MTD's through much of Euclid's oil train thread, and it seemed to be a way to achieve near-ECP performance with the flexibility to be able to apply it to any train where it might help because of terrain or whatever. However, the only advantage would be near instantaneous application of all brakes, which the professionals here seem to be saying is not that important. There would still be no graduated release feature as in true ECP. All things considered, it's probably not worth the effort and expense.
For full EPC, possibly instead of huge oversize airtanks, simply have two airtanks on each car. The conventional one that appliies brake pressure, the amount dependent now on how much pressure reduction there is in the train line propogated from the locomotive, but on EPC controlled by the accessory modified EOTDs or the electronic device built into every car that reduce this pressure at their locations. The other airtank is applicable with full EPC, and I have not figured out a way to make it work with modified EOTDS. With full EPC, the second airtank is controlled on brake release to open directly to the train line, increasing pressure in the train line. As pressure from the locomotive propogates, of course both airtanks are completely refilled.
So I do see a way for full EPC to do the job, with two airtanks under each car. But the modified Fred apporach will only do the job on application and not on release.
Does anyone have a better idea?
Not use EOTD's in a mid train application?
Dave H. Painted side goes up. My website : wnbranch.com
daveklepperSo I do see a way for full EPC to do the job, with two airtanks under each car. But the modified FRED approach will only do the job on application and not on release. Does anyone have a better idea?
You'd probably want to divide the 'air tank' into several units, each with its own manifold to the brake valve. Each would be sequentially 'addressed' by the ECP system so that full 140 psi "reference" pressure would be made available to the ECP brake valve following a partial release; that would then allow the ECP brake pressure to be 'matched' to the pressure elsewhere in the train through proportional modulation.
An alternative might be gas cartridges to repressurize the car reservoir to 'expected line pressure' on demand. That's one approach my father was considering for a hybrid compatible system. You can see some of the problems involved with it, though.
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