MULTIPLE FREDS FOR LOW COST ELECTRONIC BRAKE CONTROL

[daveklepper]

Tree68, of course you are correct, and I had forgotton about the two airtanks already on the car, the second for emergency applications.

At what year was the older triple-valve one-air-tank brake outlawed?

Interesting progression:   First straight air, no airtank on the car; then triple-valve, one air tank. then two, and for full ECP three!

[Wizlish]

Only just saw this.

dehusman

You can't mount the MTD's (mid train devices) on the side of the car, that would provide clearance problems to structures and adjacent tracks. You would have to have some way of connecting it to the air lines without the hose dragging on the track, but adjust to mulitple variations of mounting arrangements and still have flex to adjust to different draft gear arrangements.

As I understand it, the "MTD" is a box to which the air hoses from the two adjacent cars connect.  The same sort of arrangement used to hold the hose connections on intermodal trains would be used to suspend the MTD in place.  I am expecting there will be some sort of lock on the gladhands on both sides, with at least a two-stage control so that it can be set 'at a glance' to release on one or the other side as desired.

How do you make a set out with this arrangement? The set out has an MTD in it, if you turn the angle cock at the joint and come off with the head end, the EOT and rear MTD's going in emergency will put the head end in emergency.

You would disarm the MTD (probably a multi-step process for security, but a simple and easy-to-remember process) just prior to closing the angle cock, then arrange for the device to 'go' either with the set-out car or the one staying in the consist.  I may be missing something here about complexity, but I'm not sure what it is.

[tree68]

daveklepper

...instead of huge oversize airtanks, simply have two airtanks on each car. 

Which would bring the total of tanks on each car to three.  There are already two - the service reservoir and the emergency reservoir.  Read Al Krug's treatise on air brakes for a full explanation.

[Wizlish]

rdamon

Found this photo of CN's Air Container from 2009 .. 

http://www.railpictures.net/viewphoto.php?id=272091

 

Or the older 'air cars' like the one jrbernier mentioned when the distributed air container first came out:

[There was a linked picture here, from a 2009 thread on the topic of Distributed Air Containers, but our magnificent forum-software instantiation cannot or will not link it here... it was one of the Great Northern 'air cars'.]

 

Ir does occur to me that dedicated barrier cars could be easilt fitted with a small compartment with a genset and compressor 'midships' -- surrounded by sand or other buffer material in all likely contact directions -- with one of these cars cut in, say, as often as some of the WWII 'oil tanker trains' seem to have had them cut in.  It would be comparatively simple to have the "MTD" apparatus co-located on such cars, but not a requirement; all the compressors would run to build up trainline pressure after a release.  I might mention that some other means of providing fast recharge of the trainline -- Mr. Klepper's Really Big Air Reservoir, for example -- would work as well as a dedicated compressor apparatus in some respects, and not pose as much of a maintenance or accident hazard as a motorized, or battery-powered device might.

[rdamon]

Found this photo of CN's Air Container from 2009 .. 

http://www.railpictures.net/viewphoto.php?id=272091

[daveklepper]

No argument with new equipment.

And  preserving compatibility is relatively easy.   (New car in standard train, not the other way around.)

[jeffhergert]

daveklepper

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?

 

If you want to have ECP brake operation, install and use ECP equipment instead of trying to modify existing conventional air brakes to operate like ECP.

Jeff

  

[Wizlish]

Paul of Covington

But if we start adding extra tanks to each car, we may as well go with full-fledged ECP since we've lost that flexibility.

The extra tanks are only on the cars with ECP, in order to give them the capability of fast modulated RE-application after a graduated release.  In emergency there is no trainline pressure to recharge their reservoirs from.

The standard Westinghouse won't release until the trainline pressure comes up ... to the point where the reservoirs will have equalized at reasonable pressure for a re-application.  So no special arrangement other than 'distributed' admission of charging air to the trainline at multiple points is going to help the non-ECP setup.

Now, this brings up another issue of train dynamics:  if you start releasing the brakes with a distributed pumping-up, the brakes are going to start coming off some blocks of cars before others.  That should not happen too quickly!  So perhaps it is best to accept that the multiple-MTD system is for quick braking, and not for ECP-like train handling improvement...

[Paul of Covington]

   I think we have different goals here.   My reason for using MTD's was to be able to apply some of the advantages of ECP to any train, but I've decided there is not much to gain with my scheme.   But if we start adding extra tanks to each car, we may as well go with full-fledged ECP since we've lost that flexibility.

[Wizlish]

dehusman

Not use EOTD's in a mid train application?

He means his "MTDs" that are basically the 'emergency vent' in a so-equipped EOTD put into an addressable midtrain box 'hung' in the airline between two cars.  Wasn't that clearly established earilier in the thread?

What are the drawbacks of introducing "pumping" pressure at each of these valves, to restore effective trainline pressure in a rapid and controlled fashion, to produce a release?  I think there may be a way to do that without locomotive-style compressors.

[Wizlish]

daveklepper

So 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.

[dehusman]

Not use EOTD's in a mid train application?

[daveklepper]

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?

[Paul of Covington]

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.

[daveklepper]

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. 

[M636C]

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.

 

if the ability to run vehicles in either air brake or ECP brake trains is important, cars can be dual fitted, as has been described above. I don't know how the conversion is acheived but it could be set up so that the presence or absence of the 230 volts DC ECP bus line voltage triggers the brake mode. This will cost more than straight ECP at least for new cars. If existing cars are being converted, the additional cost will be less if the existing triple valve is retained.

 

Locomotives are less complicated than cars. Already in Australia, Pacific National has been temporarily equipping non ECP locomotives with through cables. A locomotive with a through cable can haul an ECP train in MU as long as the lead unit has ECP brakes. So for unit trains that have say three units at the head end, only one needs to be ECP equipped and the through cable on the other units could be strung along the side with cable ties if necessary. Most recent locomotives, since about 2005 in Australia, have ECP compatible brake controllers and can be converted to ECP operation relatively easily. The 120 1996 built Cv40-9i units have been having their brake controller replaced anyway since the cab electronics are becoming obsolete (and new 7FDL-16 engines are replacing those that are life expired). Ten of these were converted to ECP operation but the remainder could be modified at low additional cost. BNSF could update Dash 8 and Dash 9 units to ECP compatibility if they are converted to AC for example.

 

But locomotives could be routinely fitted with through ECP cables during routine overhauls at very low cost and could be available to operate in MU behind an ECP unit with little effort.

 

But the same incompatibility issues arise in Australia now and the operating companies with few exceptions run both ECP and non ECP trains and nobody has raised concerns about compatibility, even Pacific National which run unit coal trains in the NSW Hunter Valley with both conventional and ECP unit coal trains. You often see ECP locomotives hauling conventional trains and non ECP units with through cables on ECP trains (but these units are progressively getting full ECP capability, having been purchased with EPIC II brake controllers).

 

And this is all being paid for by the train operators and no outside authority told them to buy ECP. They all decided the additional cost was worth the operating savings, just like Quebec Cartier did (but PN run on normal tracks with trains from other operators and passenger trains in the mix).

 

 

 

M636C

[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."

[BaltACD]

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.

[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

[tree68]

daveklepper

Normal 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.

[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.

[wanswheel]

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.

 

The sales literature gave me the impression ECP was at the engineer’s discretion, even within one braking procedure, that the technology was so sophisticated he could easily switch back and forth from ECP to ABDX (or whatever) about as easily as if from AM to FM on a radio. I don’t know beans, of course.

[BigJim]

daveklepper

Normal WEstinghouse:  Emergency: the car's air tank is almost emtied

Is not!

[jeffhergert]

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.  

Jeff

[daveklepper]

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.

[BaltACD]

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?

[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.

[jeffhergert]

How does the redesigned ETD/MTD release the brake application?  

Jeff