Fun w/Artificial.

Short Answer: BLE 643

https://grok.com/share/c2hhcmQtNA%3D%3D ... 2f0663ad31

Grok? I'm surprised it didn't say the Kriegslok.

I'm not surprised you had nothing useful to say.

I would be interested in seeing design thoughts on practical locomotives of sizes, particularly something ideally suited to a typical short line tourist operation. The 2-10-4 suggested is enormous. I wouldn’t think it especially practical even for a bigger main line operation.
While sifting through the remaining stock of steam locomotives in the US and Canada for potential purchase, I find myself checking a few basic criteria first to decide if it is worth further consideration; wheel arrangement, engine weight and driver diameter. For my purposes, something like a 10 wheeler or consol or light mike in the 80-100 ton range with drivers somewhere between 55-63” seems ideal, based on currently operating engines. Particulars of tractive effort, cylinder dimensions, boiler pressure and weight on drivers seem to fall into typically acceptable range.

Thank you for the substantive response, it is a dignified and refreshing change of pace from the prior one.

I could have asked DeepSeek, which I’m sure would have been more amenable to the prior respondent’s irrepressible political considerations, but I would have expected a recommendation of a Datong Built QJ, given Chinese industrial practices.

The admittedly arbitrary design parameters are somewhat chosen from the Pocono Mainline that goes East to Moscow, Goldsboro, Tobyhanna with a present ultimate destination of Slateford Junction, although if memory serves, only one or two places have that demanding a grade. I think Myrtle Street, just East of the tunnel is 1.8ish. I was thinking a 600 ton train would be eight coaches or so.

I Think my omission of a driving wheel diameter (and grate area and curvature and..) was a glaring oversight of critical design parameters, however it was considered in the thinking of the model, and you can see that it even considered comically small diameters.
Obviously, a 2-10-4 is ridiculously oversized, but then again there was an attempt to obtain the BLE 643 in the heady days post grand opening. The 2317 could easily pull six coaches and eight in favorable conditions, so I’m not sure why it didn’t suggest a small Northern, or Berk something with 60,000 pounds of TE.

My conclusion is that AI is fun to play with, but not really capable of providing definitive answers, just yet. I suppose however as somebody who remembers when computers came with 4.77mhz processors, tiny, pixelated monochrome displays and 5.25” truly floppy disks, I guess I shouldn’t preclude astounding developments (that might hold as much peril as promise)

What the excursion business really needs if it is going to have much of a future is a "new" old-looking standard gauge coach that looks like a heavyweight, but is an improved and reliable version, kind of like the replica coaches the EBT recently bought.

It has already been designed; USRA Mikado, either heavy or light, depending on your track structure. A Mike could run just about anywhere, and you don't really need a 'passenger' engine like a Pacific. The Mike's lower drivers would produce more tractive effort than a Pacific, and would let you pull more coaches. TE is more important than speed in this application.

Another design that has intrigued me, for a short, three or four car heritage railroad application, is the O'Connor/NPS/Kloke design 4-4-0. Very basic, as basic as you can get! I understand that there were a few bugs that needed to be worked out, but all the drawings are public domain (thanks to NPS). Take the smaller driver diameter version (57 inch vs. 62), bump the boiler pressure up a bit, bore out the cylinders an inch or so, and you could have a nice small tourist line engine. Dress it up any way you want, 1860s to 1910 (as modernized) or so.

The original question really didn't specify what kind of excursion service such a newbuild would be used for. There is a difference, which I'm well aware of, between a Mikado and an American. Just throwing this out for thought; that's what this thread is all about, right?

If the operation in question is steamtown, I agree that ideally a moderate size northern would seem appropriate. Witness the performance of 2102 all over the mountains nearby. The old DL&W is a hard pull east out of Scranton, as most people on this forum probably know. 2317 was a helluva show working the grade, as mentioned, 8 cars might be about the upper limit without help, I don’t know precisely. I was in the cab once years ago Scranton to Moscow, the performance was impressive but it was working quite hard.
One other consideration for a hypothetical new build should be roller bearings, on journals and rods. This would greatly reduce maintenance, which is exaggerated operating on those heavy grades.

We probably should consider that the classic mainline excursion, on a Class One railroad, is a thing of the past. So, here's my take on this concept.

Two or three "stock" sizes:

Large-ish: Rutland 4-8-2, a good-sized locomotive but not huge like a big 4-8-4. 174 tons, 54,000 TE, would operate on 90 lb rail.

Medium: A 4-6-2 of about 115-120 tons, such as a CPR G5. 34,000 TE. Has a trailer axle for help in backing moves, will operate on 80 lb rail. Basically the equivalent of a GP9 or RS-3. Another possibility would be copies of the Chinese SY, without the oddball piston valves. The SY is about 102 tons.

Small-ish: A 2-8-2 or 2-6-2 of about 75-90 tons. McCloud River 2-6-2 25 is an example, Valley Railroad 2-8-2 40 or Yreka Western 2-8-2 15 are other examples. Good on lighter rail, plenty of TE for shorter and slower operations.

All should have welded boilers, roller bearing axles (drivers possibly on oil boxes), pressure feed chassis lubrication, oil fuel.

A nice conjecture, eh?

Howard P.

Is a trailer axle really needed? Strasburg's engines spend 50% of their runs in reverse and none of their engines have a trailing truck.I'd start by assuming that the typical US short line now has track and bridges designed to handle 286,000 lb freight cars, so the new design can have higher axle loads. I'd also assume we would be designing an engine that could pull a decent size train upgrade at speed (like on the BM&N, Grand Canyon, Steamtown off-site excursions, etc.) as efficiently as possible.

So I'm thinking an LS&I-like 2-8-0 with the boiler pressure increased to 300 psi -- though it'd probably need an all-new firebox design to produce the 300 psi.

The design goal would be a locomotive that was roughly half the size of a big boy but would produce 60-75% of a big boy's tractive effort.

You really need a trailing truck if a steam locomotive is going to be towed/operated in reverse at any significant speed, for any distance. The Ohio Central wouldn't let G5 Paciiic 1293 be towed backwards on the CVSR at more than 20 mph, and while METRA towed NKP 765 backwards at 70 mph on the Joliet trips, I'm told they weren't happy about having to permit that, and the 25 mph they were pulled backwards at on the recent W&LE employee trips is their preferred reverse speed. Most steam locomotive trailing trucks don't have the built-in flexibility to lead into curves the way their pony trucks do. A new design that specifically takes being able to operate in reverse at-speed would be necessary.

On the trailing truck issue, I’d say it’s a good point that Strasburg gets by pretty well without any. Of course, I would bet that lateral wear on the rear hubs is greater than the rest. Possibly on the flanges too. The additional complexity and expense would have to be weighed against benefits. And what is the principle purpose of a trailing truck? To support the back of the locomotive? Maybe to reduce axle loads?
Regarding a trailing truck’s ability to help guide an engine running in reverse, my thoughts are that it would need to be incorporated with the equalization of the rear driver, much like a pilot truck is to the front driver. Problem is, of course, this would change the whole “3 legged stool” arrangement of the equalization, essentially making it a 4 legged stool. I do not know what sort of unintended consequences that might produce. One would think that if it were that simple, it would have been done many years ago. Maybe it was? I don’t know.

CNR 47, an example of the X10t

4-6-4 tank locomotive, originally constructed to pull light commuter trains without turning. Reportedly an easy steamer, economical to run, capable of pulling several loaded passenger cars.

Three remain in existence, two potentially available for reconstruction.

DLM, the Swiss company that came from the steam shop of predecessor SLM, did a preliminary design for a double-ended 4-8-4T in 2008. I believe it was intended for the Netherlands.

https://dlm-ag.ch/wp-content/uploads/20 ... zyl_sw.pdf

Some minor cosmetic alterations would make this perfectly acceptable for US service.

These are the same guys that designed and built all-new modern rack steam locomotives for railways in Switzerland and Austria in the 1990’s. Since then, they have done several steam locomotive modernization projects as well as some ship conversions from diesel back to steam.