dehusmanNot 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.
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.
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"A stranger's just a friend you ain't met yet." --- Dave Gardner
Paul of CovingtonBut 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...
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?
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
No argument with new equipment.
And preserving compatibility is relatively easy. (New car in standard train, not the other way around.)
Found this photo of CN's Air Container from 2009 ..
http://www.railpictures.net/viewphoto.php?id=272091
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.
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.
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...
Only just saw this.
dehusmanYou 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, 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!
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