The original thread was looking for what had been in the development line of the three major American builders in 1949 - along the lines steam had developed so far .
Yet , the thread went ‘off-track’ so to say and into exploring the unconventional .
Since most of the unconventional concepts would not have retained any resemblance with the classic concept of the steam locomotive but resulted in pretty much the kind of ‘box on bogies’ appearance of any Diesel or Electric - yet without , in my opinion , standing any chance of reaching competitiveness with Diesel or Electrics - they present a totally different look-out .
Sorry , at present the split-up " Extreeem Steeam !" is a mess - hopefully it will get sorted out …
Meanwhile , let’s get back to the original question :
What further classes of ( conventional , i.e. in line with development so far ) steam locomotive could - realistically - have been expected to appear from the three builders had steam development been continued post 1949 … to , say , some ten more years ?
I think , notes posted before on Duplex engines were a likely option … what further wheel arrangements could have been turned out ?
Hi Juniatha! As far as developements in steam had it continued another ten years, I think the biggest change would have been welded boilers. The Delaware and Hudson tried welded boilers in the late 1930’s and they turned out to be very successful, so there’s a good possibility steam builders would have followed suit. Possibly other changes in manufacturing techniques as well, say making greater use of castings as opposed to machining from steel billets to speed up production.
Different valve systems might have just caught on, say poppet or Capriotti’s, as it was they came along just a little too late.
Different wheel arraingements? I don’t know, I think all the practical possibilities had been tried so I don’t know just where they could have gone past the 4-8-4 dual-purpose type. The duplex types tried by the Pennsy turned out to be an answer to a problem that just didn’t occur, not that they didn’t work well.
The “what if steam lasted” question kind of reminds me of the question of “what if the jet engine had never been invented” question in aviation circles. The US Air Force might still be flying P-51 Mustangs! Wouldn’t THAT be something!
How about a 2-10-10-4 Simple Articulated Call it the Super Texas type. Think about it the 2-10-4 Texas was considered the Best Fast Heavy Freight mover for a Single Coupled Engine out there. Now take 2 sets of their Drivers set up for High Speed Running give them a Boiler and Firebox that could handle the Steam Needs and Turn that monster loose. Bet the Big Boy and Alenghny lovers around here would go Crap we got Slammed.
The first thing that a railroad would be looking at in a new steam locomotive is how much money will it save to buy a new locomotive vs keeping an older one? Cost savings could come from reducing maintenance, increasing tonnage ratings and reducing fuel/water consumption.
I rather doubt that new steam would have been sold to the western RR’s due to lack of water in some cases and long hauls for coal, along with diesels adapting well to both mountain and low grade railroading. Going to larger articulateds would involve investment in longer turntables, so I would rather doubt seeing exotic new wheel arrangements.
What would make sense for the likes of the steam hold-outs (IC, NKP, C&O, N&W) would be a 2-10-4 or 2-10-6 with a welded boiler, poppet valves, all roller bearings, booster and either a Geisl ejector or another improved front end design. In addition, there would be a lot of effort put into making maintenance as easy as possible - along the lines of what the N&W did with their post war locomotives. The idea of the improved Texas type is to haul longer fast freight trains than the existing Berkshires.
I would expect the combustion chamber to be even longer on a new design, if for nothing else than to promote more complete combustion for reducing air pollution.
Another line of development would be detail improvements to the Y6b.
The only other line would have been follow-ons to the Jawn Henry.
Most of the recent contributors speak far above me for me to sound anything more than a dilettante. However, there always seems to be the restrictions in the boiler and throughput for both boiler heating and steam efficiency. I think this may have been the stemming point to the way the other thread evolved.
So, let us suppose the boiler and firebox configurations remained largely unchanged, including feeder and pre-heat and super-heat systems, syphons, etc. Do we want an even larger boiler, either in diameter or length, or maybe some of both? If we don’t, how many coupled or driven wheels could be placed under the boiler, but not under the massive firebox needed for ever larger steam demand from larger boilers? Or, should we keep the boilers smallish, but haul more capacity tendered and provide dual feedwater pumps?
This is my preamble to the question of wheel configurations. Unless I am mistaken, a pilot truck of at least one axle is essential to help keep a steamer running smoothly down the curves. Could we have steerable front coupled axles? Diesels don’t seem to need pilot trucks, and some of them move at a frightful clip when necessary. But, if we need a pilot truck, it limits the number of drivers. If you want to support a massive firebox, ditto.
I have always wondered if a ‘transmission’ couldn’t be added to a steamer. I realize that the cut-off provides a measure of steam efficiency, but I have wondered if the length of the main crank had to be fixed. If we could figure out how to do it, the crank could be turned outward along a track of sorts for greater leverage on start-up. While hooking up, the crank could also be screwed back up toward the hub so that there is less thrashing, a tighter turn about the center of rotation. It would add complexity, surely, but also weight that would have to be countered.
Considering Crandell’s comment about a 2-10-4 being the epitomy of steam success, I think that the available wheel arraingments at the end of the steam era were as far as they could probably have gone without going to the ridiculous but then who knows? Fifty years earlier (1900) steam locomotive designers thought they’d gone as far as they could, and as we know events certainly proved otherwise.
As a guide I think in this thread we should pretend the diesel engine itself was never invented. As it was, it WAS invented, and steam was dooomed no matter what improvements could have been made.
You know, in 1900 some railroad experts thought electricity was going to doom steam, and of course it did, but not in the way they expected.
OK, let’s use 1950 (Cunningham patent) and 1952 (Smith’s instantiation of Franklin type B on ATSF) as the relevant timeframe, as both those systems were essentially available in 1949. You’d have Snyder preheaters, Cunningham circulators, and some careful applications of internal flow both in the radiant section and in the convection section (probably done through taps on the Cunningham system). Longer-travel valves, either with some flavor of Trofimov or with Wagner bypass a la ATSF. More careful attention to balancing – rodwork closer to center, better suspension, better compression control (better than just Okadees with accumulator reservoirs) and the like. Zero overbalance, with better side bearings and lateral compliance (Fabreeka having been conclusively utilized in the Centipede tenders) and both the machinery and support for very precise dynamic balancing rods-on and then trimming for rod thrust. Duplex would have to be conjugated to be practical – Riley Deem’s gears would do this. Not difficult to put analogue to Spicer drive on non-lateral-motion axles and conjugate either with a Ferguson clutch or the Bowes drive. I’d expect type B poppets on any really fast power, but NOT with the intentionally restrictive poppets put on NYC 5500 to ‘match’ sisters’ IHP at lower fuel and water rate. If you’re building an updated T1, you might not need Smith’s recommended larger grate if all water-rate-reducing mods are implemented. Far and away the best ‘development option’ for 1949 would be the PRR V1, which was actually approved for production during WWII and was only not ‘proceeded with’ because of practical road diesels. This had a Q2 boiler and two Westinghouse direct-drive turbines, each geared to four axles and 48" drivers. The thing that made this practical was the Bowes drive; with it, you have a ‘dry’ method for matching turbine shaft speed with road speed. Comparing anything contemporary with this – the only thing
Crandall: two short points: Change-speed transmissions on locomotives are difficult and comparatively expensive, because their construction has to be far more robust than just ‘scaling up’ examples from automotive practice. If you look at the final drives of any of the contemporary turbines, you will get some idea of what’s involved. Then can be done, and a couple of my designs did in fact work them out, but the cost-benefit for railroads in our period would almost certainly not have made them worthwhile. The one exception would… or perhaps ‘might’ – have been a Ljungstrom-style balanced double turbine on an S2-style locomotive, where both change-speed and reversing could be introduced at the turbine output shaft. Synchronization is then the ‘fun’ exercise… With regard to steerability, a proper 2-wheel lead truck IS essentially radial-steering, provided only that its effective radius and centerpoint give the correct geometry on deflection. The issue then becomes how the restoring force, compliance, etc are managed, especially at higher speeds, to give the ‘right’ combination of minimized flange force and proper
Oops… chassis steering. You won’t do this just by separating vertical load at truck centerline and restoring forces, although that’s a big step forward. Assume 3-axis strut control over axle motion, for example (it was contemporary in French electric locomotive practice, and could easily have been adapted…)
I am just scratching the surface in terms of figuring out “the story” on stability of wheel-on-rail, why steam locomotives needed “pilot wheels” and why Diesels don’t.
On the 5AT steam project Web site, I found some discussion of tracking stability of steam locomotives, that most approaches to that were cut-and-try, but that a fellow named Carter from England had written scholarly mathematical and engineering papers on the subject in the 1930’s.
If a wheel is forced to roll in not quite the direction it wants to go, there is this effect called creep that allows it to roll that way in exchange for offering some resistance force to being steered that way. The amount of allowed creep is small, so for any substantial difference from the way to wheel is directed and the curve followed by the rails, the wheelset (wheel pair connected by an axle) will be in a partial slide.
In a conventional steam locomotive, the drivers are held quite stiffly in a rigid frame to facilitate connecting them with the rods to the cylinders. Given the long rigid wheel base, the drivers will be in a partial slide for being pointed not quite the right way for anything but the most gradual mainline curve. As such, creep forces do not come into play in stabilizing the tracking of the drivers, and the one paper by Carter I looked at suggests that the entire rigid wheel base can be treated as a single wheelset.
A solitary wheelset is unstable and will “hunt” or “nose” back in forth in direction. When that wheelset is pointed a little off the track direction, it will roll to one side, placing a larger radius of the taper of one wheel on the outside track, the lesser radius of the taper of the other wheel on the inside track, steering that wheelset in the opposite direction. Problem is that it overcorrects in steering and will hunt or nose back and forth as it rolls down the rails.
I’m curious about your having seen any of the literature describing the PRR’s testing of the DD1 and GG1 locomotives? The PRR picked both designs after testing them in comparison with other electric locomotive wheel arrangements as the DD1 and later GG1 were easier on the track than competing designs. The PRR engineers attributed the difference to the asymmetric wheel arrangement of the DD1 and similar argument with respect to the GG1 where each half of the locomotive was asymmetric at least in regards to the pivot points.
My guess is the asymmetry would lead to two different hunting resonances, as opposed to two equal hunting resonances with a symmetric design. Note the “symmetric” steam wheel arrangements, specifically the 4-6-4 and 4-8-4 use very different designs for the leading and trailing trucks.
Keep in mind that the 2-6-2 was a popular wheel arrangement for rod type logging locomotives, with the trailing truck added to improve tracking in reverse.
[edit: A 1940’s issue of Trains had a “spec sheet” for the Western Maryland 2-8-0’s. What caught my eye was the axle loading for the lad truck was half of the axle loading for the drivers, i.e. the WM loco was an 0-8-0 with improved tracking.]
Nope, the Big Boy and Alleghany lovers would say “oh crap, the 2-10-10-4s all got cut up for scrap because of their tendency to derail and destroy track”. There really is a limit to how big a locomotive can be, I doubt even a 16 driver version of the Alleghany (i.e a 2-8-8-6) would have been practical.
This talk of wheel arrangements and diffferent internals is interesting, but I wonder what greater use might of been made of more modern materials. Say for example, stainless steel for its corrosion resistance in non-boiler areas. Or aluminum for running boards and cabs. How about corrosion resistant or corrosion proof linings for boilers? Pyrometers or other temperature sensors to monitor the firebox to prevent over-firing or under-firing? Could greater use of roller bearings and automatic forced lubrication have been made? I could go on but I think everyone’s gotten the picture.
The point is I think the basic machine had gotten as far as it could, what could have been done to make building one easier and extending the service life and maintanance intervals?
Well, what is a “DD1” but a double 4-4-0 (Pennsy class D) wheel arrangement; a GG1 but a double 4-6-0 (Pennsy class G) wheel arrangement? That much I had read about prior.
The interesting thing about a GG-1 is that it is two 4-6-0 Ten-Wheeler types connected back-to-back with a kind of kingpin drawbar, with one 4-6-0 at all times going full speed forward and the second 4-6-0 going full speed backward. And the GG-1 superstructure kind of floats on top of those two sets of 4-6-0 running gear.
Who would have thunk that a Ten Wheeler could go at 100 MPH speed in reverse, with drivers leading and pilot wheels trailing, but it does as half a GG1. OK, the pair of 4-6-0 running gears are tied together through a kingpin pivot. I suppose you could do the same thing with a Ten Wheeler steam engine, connect it through such a drawbar to a 0-6-4 “pedestal” tender? Arrange the coal space for vision from the cab and have a high-speed bi-dire
Past 1949 would have probably seen bigger locomotives employing more modern technology and materials. Maybe a new class would have been developed as well… like a “triple articulated”…i…e. a 4 6-6-6-4… greater articluation would result in less stress on curves and would allow somewhat bigger and heavier locomotives.
The first thing to run out in the tender is usually water. I wonder if the western railroads would’ve followed the example of South African Railways’ Class 25 and built condensing locomotives. They were highly efficient machines, good for 500 miles between water refills. They were very complex and therefore harder to maintain, but so was Pennsy’s S2 turbine and (I know it’s not a steam locomotive) UP’s coal turbines. I imagine at least one would’ve been built as an experiment by a western railroad given enough time.
In the United States, extending range between water stops usually took the form of track pans (not that common), huge tenders (PRR “Coast-to-Coast” tenders) or extra water cisterns behind the tender (N&W and some other roads). Condensing tenders would tend to be viewed as an unnecessary complexity.
Let me know if you find anything interesting with respect to the PRR tests. Middleton mentioned the testing for both the DD1 and GG1 in “When the Steam Railroads Electrified”, and the engineers postulating that the asymmetric wheel arrangement led to lower track forces. This was noted in the comparison between the R1 (a 4-8-4 wheel arrangement) and the GG1 (a 4-6+6-4 wheel arrangement). While Northern’s have the same wheel arrangement as the R1, the engine trucks and firebox trucks are different designs and mountings.
I’ve also run across a couple of references about the articulation of the GG1 running gear (and other electric locomotives, e.g. the Little Joe’s) reducing hunting as yawing of one of the trucks causes and almost equal and opposite yawing of the other trucks. In addition, the tractive force passed through the articulation acted to keep the trucks in line - as long as the locomotive was pulling, not pushing.
White’s “The American Railroad Passenger Car” references testing on high speed trucks by Karl Nystrom of the Milwaukee Road, with comments about wheel shimmy. This included a quote from one of Nystrom’s assistants in the March 1945 issue of Railway Mechanical Engineer, page 108.
Asymmetry by itself is unlikely to be a cure-all, as the “Maximum Traction” trucks
A little off-topic, but deserving of a response here because of commonalty to steam issues:
All you really need to know about PRR frame stability can be seen in the difference between the DD1 and the L5. Staufer covers this relatively adequately. Long rigid wheelbase is not preferable! (Some of this might have been addressed on an L5 chassis with four-wheel lead and trailing trucks, or placement of the motors to give lower polar moment of inertia, but it still isn’t anywhere near a high-speed locomotive!)
Likewise, the R1 had the high-speed issues of the P5, now with even longer chassis and four axles without optimized lateral compliance. Not a ‘failure’ in the sense it was unworkable, just Not The Equal Of An Articulated Underframe. Note that even the larger engines in the 1942 motive power planning all had articulated underframes (and 428-A size motors) – the DD2, the “GG2”, and the eight-axle pushers/snappers). Note also how quickly and definitively the P5s were taken out of fast passenger service.
GG1 will run in push as fast as in pull, given a little bit of adjusted compliance at the articulation point between the underframes, and a bit of care with the lateral in the four-wheel truck and bolsters.
The big, big issue with the GG1 at high speed is precisely the issue that was identified: relative lack of braking power with mandatory lightweight consists. Admittedly with the locomotive pushing, you shift the awful wheel wear to the consist more than the locomotive – but you’re still braking that outsized 242 tons with the independent, and heating up the tires so they come off. We have modern technology to keep that problem minimized, but then you get into heat soak between rims and spokes and other matters – which you don’t have with simpler, lighter designs like the AEM-7 or FlexiFloat where guiding, riding, and steering can be handled independently… a