The best piece I’ve ever read about this topic was an TRAINS magazine article from the 1970’s written by Bill Withun(who was later involved the with the ACE3000 Project) called “Did We Scap Steam Too Soon?”.
He speculated that improved Duplex drive locomotives based on the PRR designs would have been the next evolutionary step in Steam development. The article included drawings of advanced versions of an 8 drivered duplex passenger locomotive as well as a ten coupled freight engine.
He also mentioned Lima’s late 40’s proposals for advanced super power designs, particularly the 4-8-6 they tried to market. And he discussed the possibility of improved steam turbine electric designs…
This is purely speculative, and certainly not from being well-read on steam…(cough…):
I would have wanted to see vastly improved thermal efficiency, more weight born by driven wheels/sets, and my feeling is that turbine drives was the ultimate end-point for steam…even if they had gotten it to work. Composite light-weight rods (not available in the mid-50’s as you limit us, Juniatha) would have taken care of dynamic augment and other unwanted wear and tear effects.
I suppose a boiler could have driven a turbine that drove a generator that powered driven axles with traction motors. How about a H-8-70ACE? [8D]
Using the power of my university library privileges, I was able to read Burnell, Neil. “An Appreciation of the T1 - The Enginemen’s Perspective” on interlibrary loan. Mr. Burnell interviewed crew members who drove and fired the Pennsy T1’s to address the mythology that has developed around them, about them being slippery, rough riding, poor steaming, or whatever other slander has been directed their way by the self-appointed experts.
The impression I got was the T1’s were capable engines. Yes they were slippery inasmuch as you can floor the gas pedal on a Ford Pinto and not much happens – try the same thing on a high performing sports car and you risk spinning out of control.
The crew reports indicate that they 'rode like a Pullman car" contradicting what has been written about rough riding. Maybe there is some exageration what with unsubstantiated and undocumented reports of 100 MPH+ running (well over 100 MPH), but apparently railroad management looked the other way when crews “made up time” but didn’t want to brag about how fast they were blowing through grade crossings. But there are indications that the poppet valve T1’s were kind of alike a multi-valve overhead cam car in comparison with the more conventional push-rod “Detroit Iron” that runs out of steam (wonder where that analogy came from) at higher RPMs.
As to the poppet valves and the maintenance crews, I have to order an article in Mr. Burnell’s series to get his take on that.
My take on all of that is that the T1’s were good engines, perhaps the best performing steam engines in terms of 100+ MPH with 1000+ trailing tons (the engine and tender alone accounted for an additional 500 tons).
It seems to me that the railroads that were successful in some sense in the waning days of steam, NYC with the Niagara, N&W with the J, A, and Y classes (by the way, the J and the Niagara were fine locomotives, but Mr. Burnell suggested
Paul, from what I have read of the N&W’s practice with the A’s, J’s, and Y6’s, not only were the engines well designed and built using the known technology, but also the maintenance and service facilities were designed to keep the engines on the road, and the crews were well trained in the art of running the engines.
I well remember the article in Trains in the mid-fifties that described the care of the engines, and illustrated how the J’s were kept moving so that the best use was made of them.
But, even if you increase the efficiency of your use of fuel and water 50-100 per cent but you have to manufacture your own spare parts, the cost of replacing damaged (think of the J that had the reverse gear on the left side disintegrate south of Abingdon) or wornout parts could negate the savings.
Paul Milenkovic stated, “The focus is wrong, the focus is on building a better locomotive whereas the focus needs to be on building a train operations system, concentrating on everything from crew training to maintenance and service facilities to how you keep those engines on the road and get economic return from them.”
This says it all. Railroading as a profit making venture, is a system of locomotives, cars, tracks, infrastructure, operations, etc. All parts must work together. N&W was probably the best proponent of this idea in late steam. They added a-tanks to eliminate intermediate water stops (can you imagine how expensive it is to stop and restart a 15,000-ton train?), using larger cars (70-ton instead of 50-ton), curve lubricators (yep, even in the early 1950’s). When they finally dieselized, a lot of the more modern ideas were already in place.
Getting back to the topic of the thread, can you imagine a poppet valve equipped N&W J? There are indications that N&W and Franklin were thinking about it…
Back to the topic at hand of a better steam locomotive . . .
There were advanced steam locomotives regarded as “failures”, but they had features on them that may have been worth keeping.
The C&O turbine-electrics were epic failures if one is to believe the press on them – their efficiency was less than an equivalent rod-driven steam locomotive, and they couldn’t get one to complete a trip without breaking down. I don’t know if the one-of Jawn Henry was all that bad, but I am told there were problems with water and coal dust getting into the electrics, of the turbine unit getting knocked out by a hard coupling.
But both of those locomotives were coal-fired cab forward, having the coal bunker up front, but shaped to let the driver and fireman see out towards the front. Garrets also had separate coal bunker from water tender, and run in reverse, they were also cab-forward with the coal bunker up front. I am thinking that the idea of a coal-fired cab forward or a bi-directional coal-fired locomotive is pretty much proven by those experiments.
The Pennsy S2 steam-turbine mechanical drive was not regarded as entirely successful, but what people say about that locomotive varies. Some say it was too heavy on steam at anything less than 100 MPH, but others say it used the variable steam nozzle arrangement that the British tried on a somewhat smaller steam turbine that was regarded as being at least as efficient as an equivalent piston steam locomotive. On the other hand, some write that the S2 was plagued with firebox staybolt failures, and that came from starting from a dead stop requiring a great drawdown of steam that thermally shocked the firebox, but I never heard that as a problem with the British steam turbine.
But the mechanical drive arrangement was considered successful unless people know otherwise, that of use siderods but coupling into one of the wheels with a jackshaft (maybe on the British steam turbine, definitely on
Paul, I too had wondered about water tubes over the other. I’m not an engineer, but it seems to me that heating smaller quantities ‘as needed’, or on demand, is a better way to improve thermal efficiency. But, being less than a dilettante here, I left it out of my musings above.
If exhaust draft up a stack is problematic, then don’t use it. Blowers work well, and can always be improved, or perhaps ducted works routing exhaust steam, or even condensing systems, are the way to go. Exhaust steam could be routed via a nozzle facing rearwards in a safe, if noisy, place to add a wee bit of jet-like thrust. Or, just in two directions, sideways on either side of the boiler if it must be vented. Just not so that it results in massive amounts of ambient-temp air rushing up through the grates upon start-up. I do understand that you don’t want to hamper the escaping used steam, or cause undue backpressures that end up defeating the power of the turbine.
Perhaps, and I hesitate to even ‘go there’, a single lower chassis cylinder to help lift the train. Boosters helped in earlier times. If the turbine can be held back and spooled up after 15 mph, maybe that would work.
Would anyone who knows take the time to do a micro-mini layman’s explanation of the benefits and caveats between poppet, reed, and rotary valves?
Take this for what it’s worth, but I’ve read that the “bugs” in N&W’s “Jawn Henry” could probably have been worked out if the experiment continued. As it was, “Jawn Henry” really didn’t do the job any better than a Y6b did, and at more than the cost of a Y6b. If other 'roads showed any interest in a steam turbo-electric N&W might have continued the developmental work with the eye on sales to other 'roads, thus lowering the production costs, but none did, so the project died. “Sic transit gloria mundi…”
The biggest problem with the PRR turbine experiment was the drastic drop in boiler pressure when starting. As to a future advancement for passenger steam, the reconfiguration of the boiler would have been a must. The PRR manufactured a working scale model of the S2 to try and solve this problem, but unfortunately and like the Jawn Henry project, a lack of interest put the project to bed…forever.
I think the hammer flow forces are something to contend with. I was out watching MILW 261 come past a few years ago, on welded rail good for 79 mph. You could hear the rail zinging with the rotation of the wheels, and could hear the hammer blow. My dad had his video camera on a nearby fence post, and it started shaking. I think it almost fell off. Diesel electrics with their rotary power application don’t do that.
There was an article in Trains mag, January 1979 I think, about the first PRR E7s. It came time to true the wheels on the E-units, and the round house foreman was incredulous about the miles the E’s had racked up. The T1s in his house had maybe a quarter of the miles, as they were in the shop most of the time.
We tend to forget that among the ‘Steam Turbine’ ( might one say experiments?) was the C&O’s #500 ordered specifically to power their proposed ’ Passenger Train…‘Chessie’. Unfortunately the Locomotive was a preformance dud and the passenger train was plagued by labor strikes at the manufacturer level.
And the reason for that was that the steam flow for a given tractive effort was pretty much constant from zero MPH to about 70 MPH. At 70 MPH, the S-2 was more efficient than any other PRR steamer, but way less efficient at ow speeds. Putting it another way, the S-2 could develop close to starting tractive effort at 70 MPH.
One solution would have been a variable gear ratio between the turbine ad drive wheels. Another would have been modifying the reverse turbine gearing to allow the S-2 to run forward on the reverse turbine at low speeds. Applying a booster may have helped as well.
Erik , that reverse turbine geared to assist the forward turbine seems “genius” 'cause it would keep the time of de-efficiency of the forward at a minimum. Yes, the reverse turbine also would be working at its most inefficient…
A booster (rods, pistons, cylinders designed for low speeds being carried along at 100 mph) might…might be over-stressed.
A couple of small design notes: The ‘follow-on’ to the 6-8-6-style turbine would involve a ‘symmetrical’ turbine, with HP admission inboard on either side of the ‘pinion’ and LP plenum outboard (where the necessary very large ducting could be easily accommodated). This design should allow intermediate reversing with relatively simple linkage at the initial stage of the reduction train (where the gear size and tooth loading are still comparatively low) rather than using a ‘second’ turbine at all; I’d expect most of the cost and complexity to be equipping any turbine with reversing gear (as proposed to have the reverse turbine ‘reversible’ to act as a booster on demand). As I mentioned, the V1 was more efficient than the S2 all the way up to 80mph, and with the Bowes drive might have been optimizable for higher-speed running (taller ‘final drive’ with the Bowes drive giving better torque matching to turbine speed at low rail speed). In case you’re wondering… yes, the comparative graph of TE/speed does still exist. (I have posted a black-and-white copy in the steam_tech files) Big point about modern boosters: they all had a gear drive that engaged only when ‘boosting’, meaning that at 100 moph the only incremental ‘drag’ would be the lubricant on the bull gear attached to the driven axle. That wouldn’t be particularly important. Even the multispeed boosters used air switching and defaulted to a neutral position when not engaged… A different issue: can a booster system be built with '40s technology that would work over the full range of speeds? I would say tentatively yes; there’s very little about the Lewty system as Porta proposed it RME
… that couldn’t be built with contemporary materials and methods. You’d have multiple final-drive speeds selected by air, and perhaps more than one hydraulic drive mechanism…
Not a 6-8-6; probably 4-8-4 (as wartime restrictions on metallurgy would not have applied, perhaps even during the Korean War period when 19 1001 was expediently scrapped… my guess would be that in the absence of road dieselization, the history of that locomotive would have been radically different, as would the Besler-motored B&O W-1.
The better argument might be 'when would you go for the big six-wheel trailer, a la Allegheny and Long-Compression (double-Belpaire) locomotives… vs. 4-wheel trailer with same lazy firing requirements and firebox size reduced through better thermo… vs. better engines with 2-wheel trailers (see Richard Leonard’s exploration of late NYC Mohawk practice.)
But 6-wheel lead trucks… not required for any sensible design that takes account of length in design…