The Pennsylvania did test N&W J #610 in 1944, and she ran over 110 miles an hour on at least one occasion. The main issue the PRR had was with the J’s 70 inch drivers, which they felt were too small for high speed operation. (Even though the N&W had engineered the J to run at speeds up to 140 mph. ) However, the N&W had tested a T1, comparing it with similar tests made of the J. The N&W didn’t seem to have that many problems with the T1, noting only its short stroke and lack of power compared with the J. The power was probably the selling point (so to speak) as it was needed to handle heavy passenger trains up grades without decrease in speed. I’ll leave it to you to speculate whether the T1’s were “for sale” as was certainly rumored at that time. Meanwhile, back to subject… Lois
Hi NorthWest
Piston valve gear would have helped in so far as it would have avoided obviously rapid and severe deterioration of actual poppet valves and valve gear . Steam circuit having been too free and causing slippage is a common yet ill-conceived picture . Engines with free steam flow could be as sure-footed as dull mules since at slow speed the difference between the two was tolerably small and at higher to top speed range there was no alternative because the throttled engine would just not go up to these speeds or not by exerting useable power . Compare effective work range of Chapelonized 141.P four cylinder compound with 141.R of tolerably same engine and adhesion mass : the ‘R’ would pull much the same freight train mass up a given ramp at some 40 mph , yet only the ‘little P’ would rise to speeds above 70 mph with an 800 t 20 coaches passenger train - being as sure-footed as the two cylindered ‘R’ from a standing start . In the T1 I think it probably was erratic valve events and likely steam leakages too by malfunctioning poppet valves that caused the engines to be unpredictably performing at low speed pulling and in fact all through the speed range as errors and leaks in valve gear got more and more severe with accumulating mileage . I also expect performance to have been widely differing from engine to engine since with deterioration besetting them there could be any degree and amount of malfunctions present in any engine , except - perhaps - those fresh from overhaul , although even overhauls seem to have been of uncertain quality . I know that getting poppet valves seating tight was an issue of due professional workmanship with many poppet valve engines , even in Austria where many engines had in later years been rebuilt to or equipped with Lenz poppet valve gear . It was also one major point that had led the Reichsbahn to decide not to introduce poppet valves in spite of repeated test
Watching the lead set of drivers slip on a T1, it occurred to me that this was not unlike the lead truck of a diesel. The lead truck catches the bad rail conditions, not necessarily low joints, frogs or poorly surfaced track, but factors like frost, oil or oil mixed with rainwater or dew, or my favorite, leaves. These gremlins can cause the lead truck to lose its’ grip with little or no warning to the Hoghead. On diesels equipped with ammeters for each traction motor (some GE’s have this information available) one can watch the lead or second axle break loose on hard pulls or even at 60mph in high throttle positions.
Perhaps the T1 would have been less likely to be plagued by lead unit slips had they reduced the available power to the lead unit. Maybe decreased cylinder diameter of the lead set ?
Thank you Juniatha!
Had the T-1s been built with piston valve gear, they might not have slipped as much, due to slower valve opening, and better maintenance. Am I correct in that the T-1s were the only PRR locomotives built with Poppet Valves? If so, the Pennsy may not have invested in properly maintaining them, as E7s and E8s could do the job for less [sigh]. I agree, with impending layoffs, shop morale would have been low.
rfpjohn and friend611, thank you for your contributions. Three people isn’t enough to keep a great thread like this going.
This stuff is fascinating to read and every once in a while, my dull brain squeaks out a thought which I feel may be worthy of sharing!
As for other Poppet power on the Pennsy, they equipped two K4s’ with two different Poppet arrangements prior to the T1 fleet. The 5399 showed extremely positive results, with radical increases in performance over conventional K4’s. However there were other changes in that locomotive which may have greatly enhanced the perception of the Poppet valves superiority.
rfpjohn-
That confirms my suspicions. Being an “oddball” was often a death sentence on large rosters, especially when shop crews had to learn a whole new set of procedures for a small class.
Thanks,
NW
I am delighted to see we agree far more than disagree.
That picture at the end is one of the best things I’ve seen all week! (We could Photoshop it to include various railroad paraphernaila… And YES the more stress the better, keeping it on ‘the knowledge’… ;-}
Only a VERY few comments
Well, not exactly; they are not transmitting ‘force’ when running synchronized, but at even slight difference in rotational speed provided the change occurs relatively quickly there will be torque transfer. This should be easily enough to arrest just-past-incipient slip when a relatively small amount of ‘correction’ can re-establish adhesion – i.e. before the engine can wind up substantial relative motion at the wheelrim and increasing rotational momentum in the ‘flywheels’ that are the drivers.
We then engage the sprag clutch in the appropriate direction, relatively smoothly (as opposed to a Maybach clutch, although I suppose you could use one if you wanted) and that provides positive torque capacity well in excess of what the differential thrust would provide at the engine’s most ‘efficient’ cyclic speed.
It will not spin more than a revollution before the other pair would either arrest the slip or start to slip itself, at which point the restoring force is no worse than on the equivalent 4-8-4.
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I’d like to see what dimensioning you’d propose for a viscous clutch to hold a low rpm high torque power output of a locomotive or half of it by 1950s technology
Just a few replies here, seriatim…
Hi Juniatha! Your mentioning the T1’s valve covers being removed and not replaced, probably for ease of maintanance. Good point, but the answer probably is the shop crews knew the diesel replacements were coming so there was no point in keeping up appearances. As steam was winding down most shop crews only did enough work on the steamers to keep them alive until the diesels showed up, probably by direction, these were proud craftsmen after all. More than likely the bugs could have been worked out of poppet valves but at that stage of the game what was the point?
Hi friend611! True, the N&W tested a T1, found little to nothing wrong with it, but as they had (and we KNOW they had!) the best 4-8-4 around in the Class J there wasn’t much point in buying T1’s. A real “thanks, but no thanks!” situation.
Hi Overmod! I see the name “Lady Firestorm” is enough to strike fear into your stout heart as well! She’s the only one in history to make Marines run in terror! Another story…
It’s been said before, but the fact is the Pennsy stayed with the K4 as a passenger hauler just a little too long. Had they started thinking of a replacement around 1935 or so things might have been different.
Had To Fail?
Like the Caledonian Railway Cardean Class? I believe that each one had only one driver at a time.
Looking forward to the new thread, Overmod. “Modern Steam”?
Going back to the original question, Juniatha, where do you feel the N&W would have gone if they developed steam another decade?
I don’t think so. They were evidently designed that way – I don’t think Altoona would make Baldwin-esque quality mistakes. So the question is why they would have been designed … or constructed … with that much effective dead space.
Well, there was that time that one of the Cardeans had only five drivers… 
Dedicated ;links’ were not used much in the United States, at least not in the later years of steam. There have been some discussions about why this was so, and I won’t repeat them here aside from saying it was not perceived to be as profitable…
I agree with Juniatha that establishing a ‘cadre’ of PRR engineers who liked and understood the T1 would have been preferable to the general ‘this is your new engine so shut up and run it’ mentality that seems to have applied instead.
Dedicated engine crews for a specific class sounds good on paper but it would founder on several hard realities. It would require a dedicated effort by the Motive Power people to ensure that a specific class would be consistently assigned to specific trains (possible on passenger schedules but somewhat difficult on freight). It would also require re-negotiation of labor contracts with the engineers and firemen to allow crew assignments for specific runs on a basis other than strict seniority (good luck with that). I’m aware that airline cockpit crews have to be certified on specific aircraft types as part of their crew assignment but let’s back up to 1946 on this issue.
What an example of train handling! That could have been quite the disaster…
Sad but true. The difference in average train travel distance was more of a factor here than in Europe as well.
Okay, as not to hijack this any further…
Where do you think the N&W would have gone given another decade?
I assume we would’ve seen some Y7 and Y8’s. N&W had the heavy Mallet down to a science.
I’m not sure about the A’s. If N&W stayed in its boundaries, there would likely be no development of the fast freight steam engine. However, if N&W did expand and merge with the Wabash and NKP, two notorious fast freight lines, maybe some A2’s would’ve been built.
As for the J’s, I’m afraid they would’ve been the last passenger steamers for the railroad. The 60s weren’t kind to the passenger train, and the N&W didn’t have any must-keep trains. The J’s would have been kept going until the end of passenger rail, maybe with more assistance from newer fast freight engines.
Like the Y6, the S1 might have had a future. Switchers were needed in the 60s, and the S1 was the premier steam switcher. So maybe some S2’s.
Hi Paul
quote >> Dedicated engine crews for a specific class sounds good on paper but it would founder on several hard realities.<<
Now , wait a minute - this proposal did not boil up in my brain - it was reality on several European railway systems and in fact was common sense during a long time of steam traction on these rys. : Just for example - without attempting complete listing :
LMS / LNER / GWR (SR ?) all major / most important engine classes on these ‘Big Four’ British railways from the Grouping to WW-II were run on fixed assignment , with double or triple crews .
PO-Midi / EST / NORD : at least on these - probably the other French railways to some extend , too - the most important engine classes were regularly run by ‘machine titulaire’ system with double crews , sometimes even single crews until WW-II .
DRG / DR / DB / DR-East : from the formation in 1920 to WW-II , all the more important engine classes were run on similar systems as the French , in German called ‘Planlok-Einsatz’ . This meant double or in cases single crew assignment of an engine . This system was inherited from the former Laenderbahnen , such as Bavarian , Prussian , Saxon , Wuerthembergian and others . Certain S 3/6 four cylinder compound engines on the Bavarian rys could have been run by single crew when assigned to run most important trains .
DRG and later DR also ran 01 / 03 class simple two cylinder Pacifics and other new built Standard classes on double manning in spite of their design specified for ease of maintenance and exchangeability of parts and whole components . This was resumed after WW-II on both West-German DB and East-German DR , from where DB went to ‘Americanize’ their steam traction significantly in multiple ways while DR kept fixed assignment for most of the members of more i
Oops… I’d forgotten we’d discussed the N&W a couple of days ago…sorry about that…
The most likely scenario I can see for N&W’s next passenger locomotive would be using the A’s for dual service.
Okay, so… what other wheel arrangements could have we seen, including Duplex(insert two letters here)?
The As were being actively improved in the early Fifties, and I suspect (as did Ed King) that they were not actively “improved” further because there was relatively little wrong ‘enough’ with the design to make it cost-effective to change.
I think the proposal to adapt the Q2 boiler design was a particularly attractive “A-provement” – there might be some fun discussing whether N&W would buy these new from Alco or someone else with the right kind of annealing furnace, or whether they would retain the riveted construction but without overconstraint at the waist, or whether they would themselves build the equipment to fabricate all-welded boilers. (I lean toward the last option…)
I do not know whether modifications to the Baker gear beyond putting the full-roller-bearing big ends on the eccentric rods were still required. I don’t see N&W embracing poppet valves, no matter how efficient they might have been. I would have to think, at least, about going to Web-Spoke pattern for the driver centers to keep the rim distortion down. But the boiler swap would have been the big thing, and I suspect it would have provided a dramatic improvement – be interesting to see just what could be done with it.
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As for the J’s, I’m afraid they would’ve been the last passenger steamers for the railroad. The 60s weren’t kind to the passenger train, and the N&W didn’t have any must-keep trains. The J&#
http://cs.trains.com/ctr/m/last-runs-before-amtrak/2085664.aspx
Looks like the FEF and 5 Es are working flat out! That could warrant a couple A’s.
Does anyone know what changes would be made in the proposed Y-7?
As do I. They were always forward thinking in motive power. But would they have used a Belpaire Firebox?
Rest assured, the J’s look good without streamlining, too: http://cs.trains.com/trn/f/740/p/191804/2222530.aspx#2222530
Someone remarked a while ago that the A’s are the perfect fantrip locomotive: fast and strong. I agree.
Thanks,
NW