I wonder if anyone ever thought of this...
https://blerfblog.blogspot.com/2023/02/stop-it-faster-leveraging-existing.html?m=0
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Kind of a next generation air brake repeater car?
I think we may see more widespread use of DPUs on smaller trains to accomplish a similar goal.
PS: the part about car inspectors putting these on? Remember many trains are now laced up and tested by conductors.
It's been fun. But it isn't much fun anymore. Signing off for now.
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oltmanndI wonder if anyone ever thought of this...
This overcomes some of the 3% deficit Westinghouse emergency suffers over ECP emergency -- personally, I don't consider that enough advantage to implement the system, although there is at least one person here who disagrees with that. The cardinal advantage is quick and positive application of a set -- whether commanded or the result of a UDE -- throughout the consist in a more controlled fashion. Since each individual module can execute a separately-modulated release of trainline air, you can design in a 'fence'-like separate control of brake application in different segments of the consist, which if for example coordinated with GPS/GIS information could make handling monstrain consists on undulating profiles less of an adventure.
But the issues with quick release and pressure maintaining still remain for any AAR-compatible one-pipe system, which means it would be difficult to implement any kind of gradual release -- and that is one of the great operating advantages that comes from two-pipe ECP installation.
Note that both manufacturers of ECP have long featured systems that are easily convertible from one-pipe to two-pipe quickly in the field (IIRC NYAB claims about 20 minutes). The problem is that the additional cost and maintenance of the ECP equipment on a converted car then becomes 'stranded cost' with no particular utility until an entire block can be run with a complete data/powerline and two pipes... and, as with the old joke about the wine and sewage, even one nonconverted car in a block spoils the whole party.
In my opinion, although you could gin up some system with engine or battery compressor that could simulate the 140psi supply trainline of two-pipe for a 'block' of ECP cars being run with protocol-translating modules at each end, there isn't meaningful return on the investment, especially since engine crews would have to learn all the quirks of the kludge but not be able to rely on it consistently.
(Incidentally, the 1988 version of "PTC" involved using a combination of artificial intelligence and expert-system design to simulate the correct handling of a locomotive brake valve in realtime for a known consist characteristic in 'full service' -- opening and closing the valve as needed to decelerate all the cars in a consist at maximum safe rate. The individual in-train modules that would enhance that system would also be proportionally controlled (from local logic updated periodically from the front end as communications permitted) to further enhance shortest proportional control of a set. Part of the idea was that a 'penalty braking' trip from existing ATC would, instead of firing an emergency application, start with full-service programmed set, with a later ATC sensor timed from the first one changing to emergency if the deceleration rate was inadequate to conditions -- but with the train now set up with slack out in much safer shape to tolerate an irreversible emergency set at speed.
zugmann Kind of a next generation air brake repeater car? I think we may see more widespread use of DPUs on smaller trains to accomplish a similar goal. PS: the part about car inspectors putting these on? Remember many trains are now laced up and tested by conductors.
Kinda like the Canadian air repeaters without the compressor.
RRs are finding they need to be careful what they wish for, these days.
OvermodI regret to tell you that I've discussed the idea you mention
I'm not surprised at all...
OvermodPart of the idea was that a 'penalty braking' trip from existing ATC would, instead of firing an emergency application, start with full-service
ATC is penalty brake, not emergency. Brake pipe to zero at service rate. Trying to do much more with airbrakes is like teaching elephants ballet...
Overmodit would be difficult to implement any kind of gradual release
Given that hardly anybody ever touches the automatic anymore except under duress, I'm not sure that graduated release is the shiny object it was in 1920, or even 1975...
The big advantage of ECP was slack control from whatvI remember. Stretched train stays more or less stretched.
The old way was keep things stretched with power braking. Now, bunch'em up and DB.
oltmanndGiven that hardly anybody ever touches the automatic anymore except under duress, I'm not sure that graduated release is the shiny object it was in 1920, or even 1975... The big advantage of ECP was slack control from whatvI remember. Stretched train stays more or less stretched. The old way was keep things stretched with power braking. Now, bunch'em up and DB.
That is outdated. Between DPUs and longer trains, the whole "dynamics is the brake of first priority" thing was tossed out a few years ago (at least for us). And that comes from our RFEs.
zugmann That is outdated. Between DPUs and longer trains, the whole "dynamics is the brake of first priority" thing was tossed out a few years ago (at least for us). And that comes from our RFEs.
So you have gone back to using the air brakes more again?
zugmann oltmannd Given that hardly anybody ever touches the automatic anymore except under duress, I'm not sure that graduated release is the shiny object it was in 1920, or even 1975... The big advantage of ECP was slack control from whatvI remember. Stretched train stays more or less stretched. The old way was keep things stretched with power braking. Now, bunch'em up and DB. That is outdated. Between DPUs and longer trains, the whole "dynamics is the brake of first priority" thing was tossed out a few years ago (at least for us). And that comes from our RFEs.
oltmannd Given that hardly anybody ever touches the automatic anymore except under duress, I'm not sure that graduated release is the shiny object it was in 1920, or even 1975... The big advantage of ECP was slack control from whatvI remember. Stretched train stays more or less stretched. The old way was keep things stretched with power braking. Now, bunch'em up and DB.
I can't keep up! I thought RFEs were gone with the PSR!
Wait until you have some battery locomotives in the consist...It'll be back to DB to save fuel.
I can remember riding from Selkirk to Collinwood on a van train and neither crew touched the automatic. And this was the late 80s...
oltmannd Overmod it would be difficult to implement any kind of gradual release Given that hardly anybody ever touches the automatic anymore except under duress, I'm not sure that graduated release is the shiny object it was in 1920, or even 1975... The big advantage of ECP was slack control from whatvI remember. Stretched train stays more or less stretched. The old way was keep things stretched with power braking. Now, bunch'em up and DB.
Overmod it would be difficult to implement any kind of gradual release
I can't say for other railroads, but ours like to see the slack bunched most of the time. The LEADER and TRIP OPTIMIZER auto throttles on DP trains love having the DP mid and/or rear consists shoving harder than the lead consist. Often I've watched EMS throttle down the head end and get into dynamics and then notch up on the DPs. Lots of slack action. Enough that I want to spend a day with those who program this crap and stand behind them and kick their chairs every few minutes. (And sometimes grab the chair and yank it back to simulate EMS getting out of dynamics with the head end going downhill and letting the slack run out.)
Dynamics are still preferred, supplemented by air. Power or stretch braking is still frowned upon, but they have changed the definition to allow higher throttle notches when using air. There's still enough people in charge who've run trains that understand sometimes that using the air brake is the best option.
Jeff
This idea has been tried on EOTs already, just not on a bunch of them spread across the train. On CN it was called Brake Assist, not sure about other railroads. The tail end valve tended to stick open for too long, causing delays and at least one train separation that I know of.
We're told to use dynamics first instead of air, and that can work great. Except for all the branchlines, slow orders, turnouts and yard tracks we are supposed to limit DB usage while using. And all the places where even full DB won't hold the train or slow it down enough. A few years ago they even finally admitted that the old tricks around how to get a really light brake by deliberately creating stickers are actually a good idea sometimes, this is now called "Soft Braking" in our rulebook (just make sure to clean it up when you're done with the brake).
We still aren't allowed to power brake above notch 4 or release the automatic while in throttle (not even in notch 1), even though there are times when these tactics work quite well.
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jeffhergert oltmannd Overmod it would be difficult to implement any kind of gradual release Given that hardly anybody ever touches the automatic anymore except under duress, I'm not sure that graduated release is the shiny object it was in 1920, or even 1975... The big advantage of ECP was slack control from whatvI remember. Stretched train stays more or less stretched. The old way was keep things stretched with power braking. Now, bunch'em up and DB. I can't say for other railroads, but ours like to see the slack bunched most of the time. The LEADER and TRIP OPTIMIZER auto throttles on DP trains love having the DP mid and/or rear consists shoving harder than the lead consist. Often I've watched EMS throttle down the head end and get into dynamics and then notch up on the DPs. Lots of slack action. Enough that I want to spend a day with those who program this crap and stand behind them and kick their chairs every few minutes. (And sometimes grab the chair and yank it back to simulate EMS getting out of dynamics with the head end going downhill and letting the slack run out.) Dynamics are still preferred, supplemented by air. Power or stretch braking is still frowned upon, but they have changed the definition to allow higher throttle notches when using air. There's still enough people in charge who've run trains that understand sometimes that using the air brake is the best option. Jeff
Interesting! I often wonder why the industry chases the wrong goal. RRs are transportation companies, not "safety first" companies (like NS used to be), or "fuel saving" companies, or "maximize efficiency" companies (PSR).
Being conscious of costs is not the same thing worshipping the the altar of costs.
oltmanndInteresting! I often wonder why the industry chases the wrong goal. RRs are transportation companies, not "safety first" companies (like NS used to be), or "fuel saving" companies, or "maximize efficiency" companies (PSR). Being conscious of costs is not the same thing worshipping the the altar of costs.
Remember the human reality - "Nothing is worth doing unless you do it to excess".
Never too old to have a happy childhood!
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