I know this has been discussed before and so I am sorry to broach it again, but is there such a thing as a steam valve that could be opened automatically by the exact electronic command that would stop a diesel-pulled train, so that a steam locomotive could emulate what a diesel does when it runs past a red board, etc. under PTC? The equivalent of reverser centered, train and engine brakes applied, etc.? If a valve could be located just behind the pistons that opened the steam line and the brakes applied the train would stop and isn't moving again, right? Or perhaps the FRA just doesn't trust such a setup.

Theoretically, it's completely possible for this system to be engineered. Essentially it's just actuation of values - which is typically done with hydraulics, just needs to be tinkered with to get it to operate with steam. When you boil it down to the bare bones, it's just a control systems project, need to find system gain and equations to represent the actuators. Sounds like a good "senior/final project" for a college engineering curriculum.

...but for all I know, people have designed this already and it's just never been implemented.

In my opinion, the larger issue would be testing it as I don't think anyone wants to risk damage to a historic machine. If/When (take your choice in words) PRR 5550 is completed, it would be an ideal candidate to test this as it's not historic fabric.

While not PTC, the Swedish railway museum has recently retrofitted one of their B class locomotives with "Traction Cutoff" for an ATC signal system. I believe the system also has the ability to big hole the break line with a passed at danger signal. They even managed to work in a dead mans pedal to get the system approved!

I actually think that NKP 765 would be the perfect candidate now. There are several other NKP Berks preserved, and this locomotive has been restored so many times now that any "historical fabric" argument really doesn't hold up. Seeing a mainline steam locomotive in operation at speed does more to teach people of history than certain parts being a certain vintage.

I think I even remember hearing rumors that they were considering an installation once sufficient funds had been raised. Perhaps nathansixchime would be able to clarify.

Why try rumors when you already have the 2926 receiving PTC?

“Also to be completed is installation of a hybrid Positive Train Control system, which the group has successfully tested with the cooperation of Union Pacific’s steam team in Cheyenne, Wyo. The final piece will be a PTC cab display.”

http://cs.trains.com/ctr/b/mileposts/ar ... -2926.aspx

I wasn’t aware of this. I will watch 2926’s career with great interest. Maybe even a Chicago trip? I know Metra said that they’re okay with excursions provided that PTC is onboard.

If 2926 ever goes to the Chicago area you might as well operate a Transcontinental special at that point.

And obviously, the chances of that happening just aren’t great. Not impossible, but slim. A trip like what the 3751 did in 1992 probably won’t be happening anytime soon without similar circumstances as what occurred to make that trip happen.

Thank you Steamguy, this is a bit closer to what I was hoping for with my posting. I will assume those who know can't talk about this system that I've now see referenced by two different trusted sources as already existing and apparently in trials.

But my ask isn't about how 4014 is operating, or how a system might work, but how this system being tested actually works. Perhaps we'll learn more during this tour and photos of the cab start to show up in social media.

Thanks all,

Bob

I was not aware of this about 2926. That confirms that this hybrid PTC system does in fact exist. I'm guessing we haven't heard many details about it since it's still in the testing phase. 4014 will be the first steam locomotive operating on the mainline with this system. I'm really looking forward to hearing all the details on how this works.

.

Regarding PRR8063's idea here, I'll bet there are steam-driven hydraulic pumps around, what would one of them weigh? Could a system be installed without disturbing the original fabric, say by storing the parts that would need to be cut into and producing new ones, and also tested in a way that doesn't damage anything (16 wheels with flat spots would be annoying and expensive). This IS like a "senior/final project" for a college engineering curriculum.

Yes. The Cab Signal systems installed in the 1920's had an optional Speed Control function that would stop the train if the engineer failed to acknowledge a less-than-clear signal or failed to reduce speed in accordance with the displayed Cab Signal.

PRR used the US&S pulse code system that had three signal aspects corresponding with pulse rates and one (Restricting) for no pulse or no code. PRR also successfully lobbied to forego the Speed Control function to use the same budget to install CSS over more miles of railroad.

In the late 1940's and early 1950's PRR and LIRR had a spate of fatal rear end collisions in CSS territory. The ICC mandated installation of Speed Control on all passenger locomotives. All of PRR's passenger diesels and electrics (also the E44's) received Speed Control as did some MP54's and K4's. Curiously, some P5a, GE E2b, WH E2c and WH E3b motors had Speed Control.

Today, CSS/Speed Control are an integral part of Amtrak's ACSES PTC system.

Of the two surviving K4's, 1361 had Speed Control; 3750 did not. The K4's with Speed Control were usually assigned to NY&LB trains.

As far as I know that generation of Speed Control applied the brakes but was not capable of shutting off steam or centering the reverser.

Phil Mulligan

That's the rub I think: what happens if the brakes aren't working for some reason (hit an object that bled off the brakes somehow and also incapacitated the crew?). Unlikely but I'm sure the FRA wants to account for unlikely things. D&SL "Moffat Road" 2-6-6-2 #210 ended up in pieces on Rollins Pass when it ran away light and tumbled down a mountain after a main rod broke and stripped all the brake lines and the crew bailed before it was moving too fast, so odd things are possible.

For those keeping score at home, the "balise" under the lead truck of SJ 1429 above is part of the European PTC system. It is a transponder used to tell the locomotive where it is and for the train to tell the railroad who it is. It also sends up to date civil speed enforcement data including permanent speed restrictions and temporary speed restrictions.

There are corresponding balises between the rails.

Please see Wikipedia which mostly describes the Eurobalise: https://en.wikipedia.org/wiki/Balise

Yes, there is something better than I-ETMS.

Phil Mulligan

And, oh yes, nice VW bug.

And to our European friends, how many generations separate SJ 1429 from an SJ RC-4 (AMTK AEM-7)?

Phil Mulligan