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PTC for Steam Locomotives

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  • Member since
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Posted by Overmod on Friday, May 14, 2021 2:22 PM

There is an amusing anecdote in Cook's 'Swindon Steam' about how some of this was managed.  Apparently in push mode the driver would close the throttle to simplify the fireman's winding up the reverser; the fireman would signal he was done with that with a 'toot' on the whistle.  This led to so much whistling at logical places that there were complaints...

One would figure that a fairly simple form of engine-room telegraph that repeaters the cutoff indication would serve here.  

M636C
Later locomotives intended for push pull use, including some British Railways standard types, had vacuum actuated valves in the steam pipes between the throttle and the cylinders. This allowed the driver in the remote cab to cut locomotive power immediately in case of an emergency stop. A similar system (presumably air actuated) could simplify the installation of PTC in a steam locomotive.

There is a great potential danger in such a thing if applied to North American weights and speeds; consider the likely cause of the Gulf Curve wreck on NYC in 1940, caused by precisely this action with the normal throttle.  What is needed, again, is a dashpot arrangement that smoothly and relatively gradually either cuts or wire-draws the steam to low pressure before completely cutting it off; I would argue that this might be controlled proportional to brake-cylinder pressure in the penalty-braking application of the ATC if implemented purely as part of an ATS.

I have argued in the past that a simple way (in theory) to implement this kind of 'soft' control comes when a locomotive is equipped with Porta's arrangement of four Wagner throttles (he called them "Waggoner" throttles in the ACE3000 patent) for low inline steam resistance.  A variety of devices can safely modulate these even if brakes are applied from very high road speed (and hence high cyclic, very high inertia forces, and high back pressure/compression effects if a throttle is closed quickly)

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Posted by M636C on Friday, May 14, 2021 7:36 PM

There is a great potential danger in such a thing if applied to North American weights and speeds; consider the likely cause of the Gulf Curve wreck on NYC in 1940, caused by precisely this action with the normal throttle.  What is needed, again, is a dashpot arrangement that smoothly and relatively gradually either cuts or wire-draws the steam to low pressure before completely cutting it off; 

In the UK, of course the weight of the train was negligible, even compared to the small locomotive used.

The valves had levers with counterbalance weights to allow the vacuum cylinder to act in one direction only. A dashpot arrangement could be added to this counterbalance system.

Peter

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Posted by BEAUSABRE on Sunday, June 20, 2021 11:58 AM

Isn't this a moot question for the most part? Aside from UP, which of the class 1's operate or permit the operation of preserved steam on their track? I can see it being a problem for the tourist pikes that own their own track, the D&S, CATS, Straburg and (soon, I hope) EBT, etc. I can see them either being denied insurance or having their rates skyrocket if they are hauling passengers without PTC. Yes, yes, I >KNOW< they may be exempt, but we're talking insurance carriers, not the Feds. And to non-railroaders and non-railfans, it's the silver bullet that will prevent all accidents and injuries

 

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Posted by jeffhergert on Saturday, August 21, 2021 8:34 PM

Big Bill

"The UP fleet will operate, of course..."

Nowhere have I seen anything, anywhere (maybe I'm looking in the wrong places?), about PTC being installed on the Big Boy. Or the 4-8-4. Or the Challenger.

Did I miss it?

I don't see how a diesel in the consist will stop any of these machines.

Maybe I'm all wrong, it's happened before.

 

UP 4015 has now operable PTC using the some of the onboard functions via the trailing diesel engine.  UP 844 will also be equipped in this manner.

They are exploring ways to make the steam engines stand alone PTC equipped.

Jeff

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Posted by kgbw49 on Sunday, August 22, 2021 9:38 AM

There is a picture of the PTC box in 4014 on the website under a post of what changes the 4014 has for the 2021 trip on the Trains web site.

https://www.trains.com/trn/railroads/locomotives/union-pacific-big-boy-differences-from-2019-tour/

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