Railroad Thread

[Gabriel]

[Gabriel links to some brake systems]

You are not_addressing the question.

Your links are to systems already developed.

No acknowledgement that electrical control might be needed for faster response.

I don't know. I don't even know why the trains of the accident in question decelerated between extremely poorly and almost not at all.
Unfortunately (and incredibly) the NTSB doesn't discuss that in the accident investigation report.

As you said the systems were developed. Are they being used? Are they being maintained? Am I missing something?
I don't know. Don't blame me for not addressing the question for which I don't know the answer.

What I do know is that steel on steel has a static coefficient of friction that is almost always better (and many times much much better) than 0.1. Why are we not using it to its full power? I don't know.

You just want to gripe that you think 1,200 brake shoes should make a 150-car train stop like a semi truck.

No, what I said is that a semi truck can brake in the same distance than a sedan at the same speed. Rubber on asphalt for both. Steel on steel cannot provide that level of friction, but it can still provide much more than what we see in the video.

[3WE]

[Gabriel links to some brake systems]

[…]

I don't know. Don't blame me for not addressing the question for which I don't know the answer.

What I do know is that steel on steel has a static coefficient of friction that is almost always better (and many times much much better) than 0.1.

I am mildly trolling you, but I would think an engineer who generally provides voluminous input into diverse aviation systems (including human factors and reliability), might have some additional thoughts on the engineering of train brakes.

It’s also interesting to note that there are things called flange greasers along with concerns with locomotive traction loss when wetness, snow, or leaves are present.

The engineering of this stuff is kind of cool, even though a full flap 727 dragging over the fence in a crosswind is slightly better that 3 SD-45s dragging over a hilltop or glowing brake panels on the downside…

[elaw]

Flange greasers???
\

Okay yes I can understand the need for same, especially as a resident of an area with a subway system that has a lot of sharp curves. But if the grease migrates from the flange to the horizontal wheel surface... badness will ensue.

Semi-related, I don't remember details but feel like I've heard of more than one railroadie accident where the brakes overheated and lost effectiveness going down a long grade, and part of the cause given was that the dynamic brakes on the locomotive(s) were not working. Perhaps railroading folks need to adopt the concept of an MEL?

[3WE]

Flange greasers???

***if the grease migrates from the flange to the horizontal wheel surface... badness will ensue***

The Aggie doesn’t need to have viscous fluid dynamics or differential equations to tell you that grease migration is kind of efficient.

Footnote: I have come to enjoy the development of Hikara Sulu and other characters played by George.

Do we think he likes discussing plane crashes?

We should try to get him to join the forum.

[3WE]

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IMG_0680.jpeg (142.67 KiB) Viewed 227 times

[J]

We have had a lot of discussion about braking but here is an illustration of traction.

A SD70ACC' is handling two inoperative GE locomotives and unknown tonnage.
According to the internet, this 4,500-horsepower unit was originally manufactured in 1994 with DC traction motors and then rebuilt in 2018 with AC. (A good thing because this hard start would have barbequed the DC motors.)

Look closely and you can see the truck frame moving up and down as the traction motors try to rotate out of their mountings. Considering this locomotive weighs 432,000 lbs. (195952 KG.) you are looking at a lot of energy.


https://www.youtube.com/watch?v=EXCFHnzeeco

[3WE]

Cool video.

My understanding is that AC systems provide for “easier” traction-control systems and maybe the “rocking” we observed was “fly by wire” and not the engineer switching throttle notches?

That stuff always amazes me as my household power tools do not like being stationary with lots of electricity running through them…the magic smoke starts to leak out fairly quickly.

The other major dorkism is that I THINK dynamic brakes burn a little fuel to MAYBE initiate the opposing electrical fields in the traction motors- but then the electronic wizardry takes over…or not?

/outsider, BS asshattery

[elaw]

That stuff always amazes me as my household power tools do not like being stationary with lots of electricity running through them…the magic smoke starts to leak out fairly quickly.

Keep that in mind next time you hear an EV fanboi going on about how "DC motors have infinite torque at 0 RPM"*.

As a smart person once said, the only things that are infinite are the universe and human stupidity, and he was not entirely sure about the former.

On the other hand, one big difference between most home power equipment and rail traction motors is that for most home things, cooling is provided by a set of fan blades mounted on the motor shaft, so 0 RPM = 0 cooling. I'm pretty sure the traction motors have separate fans, such that cooling can be provided when the motors are stalled.

* Just for the record I'm not anti-EV... I 100% intend to own one as soon as one appears that suits my needs and is priced such that I can afford it. But I have no expectation that it will have infinite torque.

[Not_Karl]

This was cool.

[J]

Locomotives have a tough life.

The AC motors can "hold" a train stationary on a hill with no harm and, as was said, they have more sophisticated control systems that can control wheel slip while starting a heavy train. The older DC motors were a lot easier to control but would develop "Stall burns" on their armatures if higher amperage was applied to a motor that was not rotating. That was one reason two railroads in the US experimented with Kraus Maffei diesel hydraulic locomotives in the early 1960's. All three axels of each truck (bogie) were joined by heavy shafts and gear boxes so they slipped far less than traditional locomotives of the time. They were complex and US production quickly approached their performance, so they didn't last more than a few years other than this one which was brought back from near death and now has one of its two engines and transmissions operable.

On the left of the home page, you can see its condition when donated to the museum. Much of the front had been removed so that cameras could be mounted to gather recordings that were used in a locomotive simulator. On the right you can see the nose (and cab, and one of the engines, etc. etc., has been restored. After an initial startup several years ago, the surviving engine was found to have internal damage and so has subsequently been rebuilt.

https://sp9010.ncry.org/

[3WE]

*** I'm not anti-EV ***

I am, to some degree.

I think they are a great second, go-to-work car…charge overnight.

But, young MS 3WE had a horrible experience with a rental on a business trip, in CA. Charging was a hassle and time consuming. Did I say that this was in San Diego? Kalifornia…

I call bologna on electric for travel, trucks and agricultural GMO SPRAYERS, etc.

And, of course, it’s been politicized, which is never good.

[And before you think I’ve gone off topic]

The clincher for me is that I see almost no effort going into electric trains, which IMHAHOO is the PERFECT place. Half the wiring is in place, electric-motor locomotives are also SORT OF in place…

AND WHEN IT COMES TIME FOR BRAKING, the dynamic brakes dump the electricity BACK INTO THE SUPPLY GRID, instead of the waste-it grid on the locomotive.

I acknowledge a lot of electrical light-urban rail systems, but I don’t see anything happening with freight.

If electricity is sooooo great, we should be electrifying our railroads!

[Gabriel]

Couple of things to mention.

- To start to move form zero you have a quite a bit of static friction to overcome. It takes much more power / force to just barely start moving than it takes to keep moving and even accelerating at slow speed (as can be seen in these videos).

- For traction you only have the traction wheels available. For braking you have all wheels. Braking should be much much more effective than accelerating (unless of course you are in an electric train where all the wheels of all the cars are traction wheels too).

[elaw]

The clincher for me is that I see almost no effort going into electric trains, which IMHAHOO is the PERFECT place. Half the wiring is in place, electric-motor locomotives are also SORT OF in place…

AND WHEN IT COMES TIME FOR BRAKING, the dynamic brakes dump the electricity BACK INTO THE SUPPLY GRID, instead of the waste-it grid on the locomotive.

If electricity is sooooo great, we should be electrifying our railroads!

To expand a bit on your teeny text I have 2 words: SUBWAY TRAINS.

Unlike freight trains, they're already electric. And also unlike freight trains, they spend a very large portion of their operational time accelerating and decelerating (or accelerating toward the rear if you're a physics major). And they always have an "alternate power source" available if the battery is in a mood. The ability to travel to a nearby station under battery power if line power is lost would be another big plus.

Why no work seemingly is being done in this area completely baffles me.

[elaw]

Couple of things to mention.

- To start to move form zero you have a quite a bit of static friction to overcome. It takes much more power / force to just barely start moving than it takes to keep moving and even accelerating at slow speed (as can be seen in these videos).

- For traction you only have the traction wheels available. For braking you have all wheels. Braking should be much much more effective than accelerating (unless of course you are in an electric train where all the wheels of all the cars are traction wheels too).

Imagine what life would be like if you had a small motor & battery pack on each car, to provide per-car "dynamic braking" (regen), and a propulsive boost to get the thing moving from a stop.

[3WE]

One of the things I mention.

- ***For traction you only have the traction wheels available. For braking you have all wheels.***

Thanks for the information. But, [Not italics]We even us aggies and Cajeros automaticos) already know this. Thus the sanders and flying sparks and, etc for starting the train.

In the meantime, please continue to complain and pontificate, while offering little in the way of acknowledgement of the challenges nor suggestions as to what might be done to improve the effectiveness of all those brakes and wheels.

[3WE]

Imagine what life would be like if you had a small motor & battery pack on each car, to provide per-car "dynamic braking" (regen), and a propulsive boost to get the thing moving from a stop.

I imagine it would be expensive.

To hell with batteries, just add overhead wires, pantographs and hook in downstream from the alternator…the locomotive can dump the braking power to other trains.

[Not_Karl]

I acknowledge a lot of electrical light-urban rail systems, but I don’t see anything happening with freight.

Europe has freight trainies with electric locomotivies.

[3WE]

I acknowledge a lot of electrical light-urban rail systems, but I don’t see anything happening with freight.

Europe has freight trainies with electric locomotivies.

Indeed…Especially those Krauts.

It is proven that it works OK…

I guess my point is that if it’s soooooooo important to electrify transportation, why is there sooooo little talk and effort on US freight rail?

It sure seems like a logical thing to do, and no batteries required, just an overhead wire.

Or maybe electric is not_that great? [/political blasphemy]

And don’t_forget that it’s essential to electrify everything ASAP to save fossil fuel for aeroplanies. Evan said palm oil is not_the answer.

Or was there a Frenchman-Airbus-Cheap-Composite joke in there?

[elaw]

I guess my point is that if it’s soooooooo important to electrify transportation, why is there sooooo little talk and effort on US freight rail?

Here are my guesses, in no particular order:
1) No money.
2) Long distances to be covered, which often are distantly distant from sources of electric_power.
3) Diesel engines make more noise, this is the USA, and we think louder is always better.

(1 and 2 of course kind of go together, as even more $ is required to bring electricity to the middle of nowhere)

One thing I'm 100% sure of is that auto/truck makers and big oil having lots of congressenators in their pockets has absolutely nothing to do with it.

[3WE]

I guess my point is that if it’s soooooooo important to electrify transportation, why is there sooooo little talk and effort on US freight rail?

Here are my guesses, in no particular order:
1) No money.

3) Diesel engines make more noise, this is the USA, and we think louder is always better.

1 and 2 of course kind of go together…

as even more $ is required…

…lots of congressenators in their pockets has absolutely nothing to do with it.

I concur with your whole post, but left the highlights as snicker-worthy.

And the wonderful lugging roar of a diesel engine is important- especially since Gabe’s high-bypass turbofans are nothing like JT-8Ds.

You mentioned something earlier, that commuter trains are constantly starting and stopping, where as a freight train, starts and stops gradually with, hopefully, long “cruising” times. That may limit the regenerative potential (still, large, red-hot grids with 4 cooling fans…seems like that could be used instead of “burned”.)

Also, I think RRs have used a bit of freedom in having various load heights. It might be a pain to get that standardized for an overhead wire…and crazy long pantographs.

NEVERTHELESS, Kalifornia is shoving electric trucks down our throats with LOTS of issues and $$$, while it would be easier to string a single wire up those long RR downgrades where the trains wreck when the dynamic brakes are MEL’d…

…and UP is supposedly the world’s largest user of diesel fuel…

“Congressinators”, indeed!

Footnote: Coal train at Kirkwood, Flyover (a few hundred ft climb, but the RR is renowned for having no extra power): https://youtu.be/liVFChrjcp8?si=ciSz5LHgJDvtHCt4

[Not_Karl]

3) Diesel engines make more noise, this is the USA, and we think louder is always better.

We could install fake afterburners on electric locomotivies and make them cross a wall of fire and explosions every couple kilocorgis to make them more American.

[elaw]

Or how about... real afterburners? https://en.wikipedia.org/wiki/M-497_Black_Beetle

[elaw]

And continuing the theme, our local transit authority has this: https://www.youtube.com/watch?v=DL6jKOCeVec

I've actually seen it (sitting, not in operation) a few times, though not recently.

[3WE]

3) Diesel engines make more noise, this is the USA, and we think louder is always better.

We could install fake afterburners on electric locomotivies and make them cross a wall of fire and explosions every couple kilocorgis to make them more American.

Why fake? Didn’t your spin-out link also include a fire-belching exhaust stack?

[Not_Karl]

Or how about... real afterburners?

Why fake? Didn’t your spin-out link also include a fire-belching exhaust stack?

Real afterburners in dinosaur/plant-juice-less electric motors usually result in reduced lifespan.