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120 MPH T1

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Posted by kgbw49 on Monday, January 16, 2017 11:51 AM

T1 on the turntable...

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T1 going somewhere in a hurry...

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T1 with L1 Mikado helper coming up the Altoona grade after passing Horeshoe Curve...

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T1 at speed about to hit the diamonds at Plymouth IN...

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T1 at a mainline coaling and watering station - notice train behind the tender...

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Pennsylvania Railroad travel poster...

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Pennsylvania Railroad travel poster...

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Broadway Limited travel poster...

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Advertising poster...

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S1 1939 Pennsylvania Railroad Calendar image...

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Posted by Miningman on Thursday, January 12, 2017 10:48 AM

Documented you say?...wow now that would be a good find. It certainly fits considering the rapid demise starting almost right away, say 6 months to a year after being built. 

Seems the T1 hit the proverbial perfect storm ....corporate sabotage, poor grade coal, E7's. They must have had a few friends and believers at the PRR and Baldwin but they didn't stand a chance. 

 

RME
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Posted by RME on Thursday, January 12, 2017 9:36 AM

CSSHEGEWISCH
The point is well-made but I don't think that a formal training program in how to operate a T1 could have been set up.  It would have implied that only qualified engine crews would be assigned to T1's and the operating brotherhoods would have opposed such classifications.  It would have also hamstrung the operating department because T1's would have to be guaranteed for specific runs.

Believe you me, brother, I don't argue with anything you say.  Even the use of preference in calling assignments (giving people the choice of taking the T1 as called if they knew how to get the most out of it) would likely not have passed Brotherhood muster.

What I was thinking of was more along the lines of an accelerated version of air-brake transition training in the very early 20th Century, where various means of delivering the lessons about modern 'locomotive driving' would be conveyed and reinforced.  I would argue that if this had been started around the time the S1 was being seriously undertaken -- perhaps as late as the first recognitions that the two T1s as built could be flighty -- it might have had the effect of changing default response in key respects.

Now, whether PRR as a corporation could have done this with the necessary degree of indirectness (remember the history of the Bishop coupling knife!) is another matter.  One approach that has worked in other areas is to develop a 'cadre' of people who could get the most out of the duplexes, and then have them be the developers of "training" material for others that would cater to their particular preferences and attitudes. 

Note that I dodge all the issues connected with the wisdom of issuing Ferraris to UPS drivers without any particular warning.  Or whether (as I think might be documented, if we can believe Arnold Haas, at NYC) there was actual corporate effort made to create techniques that fail, in an atmosphere of failure, to help with getting out of equipment-trust arrangements.

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Posted by CSSHEGEWISCH on Thursday, January 12, 2017 8:15 AM

The point is well-made but I don't think that a formal training program in how to operate a T1 could have been set up.  It would have implied that only qualified engine crews would be assigned to T1's and the operating brotherhoods would have opposed such classifications.  It would have also hamstrung the operating department because T1's would have to be guaranteed for specific runs.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by daveklepper on Wednesday, January 11, 2017 3:13 PM

But in the end, until the early displacement by diesels, there were engineers who learned how to get great performance from the T1s and so did.

RME
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Posted by RME on Wednesday, January 11, 2017 2:23 PM

Dr D
You indicated in your last post that (FA) Factor of Adhesion was much clearer indication of the Duplex driver slip problem. I feel that this comparison of the unreliability of (FA) to specifically disclose any clear conclusions significantly disproves this assumption. Clearly the 1/2 vs 2/3 driver weight comparison gives a much clearer picture of the problem to the average reader...

What I intended, by bringing up FA and its use as a 'rule of thumb', was to illustrate that is is not a reasonable predictor of slip propensity for duplexes.  (I have already discussed the likeliest reasons ad nauseam in other threads and will not abuse the horpse any further.)

PRR made changes that ran the FA of some T1s to 4.48, which is getting into the 'throwing horsepower away' category, and still had both the low-speed and high-speed slipping.  (I think, but can't prove without references I don't have access to, that this included the sleeving of some locomotives' cylinders, a rather extreme measure considering that stalling was an issue at that stroke even with the original cylinder bore...)

As you note, FA isn't necessarily a good predictor of slipperiness, but then again, without knowing other details about locomotive configuration or engineer training, it won't be.  It is a ratio that gives a guide to achievable adhesion.  We have ample proof that the FA of the N&W J (which is somewhat 'artificially' low due to the large weight and small driver diameter) does not mean that the engine is intolerably slippery, just that more care needs to be exerted when accelerating from a stop or low speed.  I believe you will also find that the design of the throttle and cutoff controls are important in achieving both 'fine tuning' of steam flow and rapid reduction and return for slip arresting.

Remarkably: the the Pennsylvaina Q2 Duplex 4-4-6-4 which had a (FA) Factor of Adhesion of 3.58 is astoundingly closer to that of the Diesel Electric 3.33 than any steam locomotive.

Remember that this engine is immensely heavy and has divided drive, but a very significant reason for the low nominal FA is that a very sophisticated (for its time) control system was provided to arrest slippage quickly and automatically.  Why that system did not work reliably is important reading for people designing bold new systems to address old railroad problems... Bucky, are you reading along?

 

Specifically with the inability of existing theoretical engineering models to deal with power and tractive effort relating to boiler horsepower utilization and speed. Johnson writes, "As the speed is increased, the available tractive force falls off until a point is reached at which the boiler can no longer supply the steam required by the cylinders at full stroke. IF greater speed is desired, it is necessary to use the steam more efficiently, and this is accomplished by shortening the cut-off. This procedure shortens the percentage of stroke during which steam is admitted to the cylinders, and during the balance of the stroke the expansion of the steam from boiler pressure towards atmospheric pressure does the work...It is evident that under these circumstances the tractive force that a locomotive can develop is dependent not only on the cylinder and driving wheel dimensions, but also on the steaming capacity of the boiler."

However, were you to read Johnson more carefully, you will see that he's discussing the effect produced by cutoff itself, not the distinctive advantages of poppet valves.  It's important to regulate both timing and duration very precisely for high-speed work, but the advantages come in at higher speeds than most railroads regularly worked locomotives - see the discussions of the T1 vs. T1a in sources like the Keystone to see the difference. 

New York Central Niagara 4-8-4 engine 5500 was equipped with the poppet valve gear and Paul Kiefer the Chief Engineer for the railroad considered the NYC 5500 the most powerful ever built for the railroad. Giving the NYC Niagara 4-8-4 an extremely high (FA) Factor of Adhesion of 4.47,

The last half of this sentence, and perhaps some others, are missing from the post as I received it.  But it is important to remember that Kiefer specified the 5550 to make the same horsepower as the 6000s ... think about it a moment, why would you need or want more hp out of a single 4-8-4 in NYC service ... but with much higher efficiency in both fuel and water at sustained high speed.  (LeMassena did a long and reasoned article on this in Trains in the '80s).  Even at the time the 1947 report on motive power went to press, Kiefer had no hard data on how well this would perform, but was certainly hopeful enough to cite it there.  I would also note that the proposed C1a material that has survived shows nothing but typical Baker gear - in other words, largely a duplex Niagara.

Unfortunately, NYC went with the type A gear to drive those poppets, and appear to have suffered many of the same complaints PRR did with practical maintenance.  The 5500 was laid up out of service long before most of the piston-valve Baker Niagaras were out of service, and it does not appear that NYC considered the additional maintenance and aggravation sufficiently 'worth' the saving in fuel and water to make the logical 'fixes' (cf. the valve improvements for the T1 by 1948).

Likewise the Pennsylvania Railroad T1 Duplex 4-4-4-4 of similar poppet valve design developed the principle of steam distribution beyond what Paul Kiefer did by doubling the effective cylinder capacity! Likely the power developed by this "low cut-off" steam distribution system took the T1's steam locomotive running performance at speed, and Tractive Effort at speed into undiscovered engineering areas - result WHEEL SLIPPAGE AT SPEED! a continuing and re-occuring problem because of the power developed by "low cut-off" and high steam distribution cylinder capacity.

All this would come as quite a surprise to the Baldwin and PRR engineers, who knew perfectly well what the steam would do.  (The 'surprise' was with some of the momentum effects on the Q2, which did take duplex design into undiscovered country...)

The principal problem was the physical reduction of the proportion of adhesive contact due to road conditions or shock (again, as I have covered too many times to avoid MEGO).  The secondary problem was the relative absence of means to recover from the slipping, and the tertiary was not training enough enginemen to handle advanced locomotives.  None of these are related directly to high horsepower and steam distribution in distributed drive at speed, except (perhaps) insofar as a slipping engine might 'starve' the other of working steam, causing deceleration that would complicate re-acquisition of adhesion on the slipping one.

I also wonder if the company test facility dynometer with steel wheel roller drive ever fully did, or ever was fully capable of testing these T1 performance (FA) Factor of Adhesion parameters at high loading and and under high power conditions.

The answer to the question as you asked it is "yes" (with the caveat that the physical contact patch between driver and roller is slightly different from that for driver to railhead).  The reason the 'caveat' doesn't matter is that functionally it would produce the phenomenon of slipping more readily than dynamometer testing out on the railroad would.  So the relative absence of uncontrolled slipping on the test plant came under conditions of nominally poorer adhesion, and this might have lulled the engineers into thinking the situation with slipping was not as dramatic as it proved to be.  (As a peripheral issue, there is some question whether the effect of weight transfer due to drawbar pull is less noticeable when the drivers are on independent rollers than on straight track -- personally I don't think it would be.)

The question you should have asked was whether the test plant was fully capable of testing the T1 parameters at high loading and high power in real-world road conditions.  And there, the answer is not only a bit obvious, but justified by events.

In theory, it would have been possible to put cam profiles on the rollers to simulate various types of road shock or simulate the effect of low joints or rail gaps, perhaps even making the profile servo-adjustable.  (This in fact is part of the 'roller-rig' design for testing the T1 Trust locomotive).  It would also be nominally possible to change the contact profile of the roller surfaces.  However, one key thing missing was the ability to test under reduced-adhesion conditions -- even if the test-plant engineers agreed to subject their precision machinery to gobs of dirt and ice, there is little practical testing of sanders or their alignment possible with the test-plant geometry.  All these things show up glaringly in T1 road experience, and I can't help but think that an organized dynamometer-testing series would have given better data than test-plant running in those respects.

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Posted by erikem on Tuesday, January 10, 2017 10:19 PM

Paul Milenkovic

How was Stanier's "Turbomotive" in Britain "successful" in the way that the Pennsy S2 turbine was not?  I mean the Turbomotive wasn't successful in the sense that they built a fleet of them, but it wasn't popping staybolts either, was it?  And wasn't the multiple-nozzle turbine, creating a kind of "notched throttle" the inspiration for the S2, or did they go a different path?

My understanding of the S-2 is that the steam flow rate was proportional to tractive effort and almost independent of speed. Starting a train would cause a significant drop in boiler pressure with resulting flexing of the firebox. Above 70 MPH it was more efficient than any reciprocating steam locomotive, but not at low speeds.

 - Erik

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Posted by Dr D on Tuesday, January 10, 2017 9:01 PM

RME et.al,

THE PENNSY DUPLEX AND FACTOR OF ADHESION ISSUES:

This has given me the pleasure of reading Ralph Johnson's book The Steam Locomotive, specifically chapter X on "Tractive Force"; Johnson you will remember was the chief design engineer at Baldwin Locomotive Works and the primary design engineer leading the Pennsylvania Railroad T1 Duplex experimental locomotive development of the 4-4-4-4 engines 6110 and 6111.

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To quote Ralph Johnson from his book, "The hauling capacity of a locomotive is determined by the relation between the tractive force developed and the resistance of the locomotive and train, and both of these factors are dependent on the speed.

At starting and very low speeds the power capacity of any locomotive will permit large tractive forces to be developed.  The limiting factor is the frictional resistance or adhesion of the rails which opposes the forces tending to slip the driving wheels.  The ratio or factor of adhesion is the adhesive weight of the locomotive divided by the rated tractive force and is usually about 4 although in many cases it varies slightly above or below this..."

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TRACTIVE EFFORT AND FACTOR OF ADHESION for the T1 and S1, Duplex locomotives compared to other common locomotives of the era.

Pennsylvania S1 Duplex 6-4-4-6 - Drive wheel diameter 84" - weight of engine 608,200 lbs - weight on drive wheels 281,400 lbs - Tractive Effort 71,900 lbs - (FA) Factor of Adhesion 3.92

Pennsylvania T1 Duplex 4-4-4-4 - Drive wheel diameter 80" - weight of engine 497,200 lbs - weight on drive wheels 268,200 lbs - Tractive Effort 65,000 lbs - (FA) Factor of Adhesion 4.13

Pennnsylvania Q2 Duplex 4-4-6-4 - Drive wheel diameter 69" - weight of engine 621,100 lbs - weight on drive wheels 386,000 lbs - Tractive Effort 100,800 lbs - (FA) Factor of Adhesion 3.58

--------------------

Lets examine the few other famous engines for comparison:

New York Central Hudson4-6-4: drive wheel diameter 79" - weight of locomotive 265,500 lbs - weight on drive wheels 201,800 lbs - Tractive Effort 43,400 lbs - (FA) Factor of Adhesion 4.28

New York Central Niagara 4-8-4: drive wheel diameter 79" - weight of locomotive 471,000 lbs - weight on drive wheels 275,000 lbs - Tractive Effort 61,500 lbs - (FA) Factor of Adhesion 4.47

Athison Topeka & Santa Fe Northern 4-8-4: drive wheel diambeter 80" - weight of locomotive 510,000 lbs - weight on drive wheels 294,000 lbs - Tractive Effort 66,000 lbs - (FA) Factor of Adhesion 4.35

Milwaukee Road F7 Hudson 4-6-4: drive wheel diameter 84" - weight of locomotive 365,500 lbs - weight on drive wheels 216,000 lbs - Tractive Effort 50,300 lbs - (FA) Factor of Adhesion 4.10

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Put the Pennsy Duplex locomotives in a larger context compare these:

Chesapeake & Ohio Allegheney 2-6-6-6 articulated freight engine: drive wheel diameter 67" - weight of engine 751,800 lbs - weight on drive wheels 504,000 lbs - Tractive Effort 110,200 lbs - (FA) Factor of Adhesion 4.27

Union Pacific Big Boy 4-8-8-4 articulated freight engine: drive wheel diameter 68" - weight of engine 772,000 lbs - weight on drive wheels 545,000 lbs - Tractive Effort 135,400 lbs - (FA) Factor of Adhesion 4.02

Pennsylvania Railroad S2 steam turbine 6-8-6 an all time unique passenger engine: drive wheel diameter 68" - weight of locomotive 580,000 lbs - weight on drive wheels 260,000 lbs - Tractive Effort 70,500 lbs - (FA) Factor of Adhesion 3.70

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Lets rate these engines just by (FA) Factor of Adhesion:

New York Central Niagara 4-8-4: Tractive Effort 61,500 lbs - (FA) Factor of Adhesion 4.47

Atchison Topeka & Santa Fe Northern 4-8-4: Tractive Effort 66,000 lbs - (FA) Factor of Adhesion 4.35

New York Central Hudson 4-6-4: Tractive Effort 43,400 lbs - (FA) Factor of Adhesion 4.28

Chesapeake & Ohio Allegheney 2-6-6-6: Tractive Effort 110,200 lbs - (FA) Factor of Adhesion 4.27

Pennsylvania T1 Duplex 4-4-4-4: Tractive Effort 65,000 lbs - (FA) Factor of Adhesion 4.13

Milwaukee Road F7 Hudson 4-6-4: Tractive Effort 50,300 lbs - (FA) Factor of Adhesion 4.10

Union Pacific Big Boy 4-8-8-4: Tractive Effort 135,400 lbs - (FA) Factor of Adhesion 4.02

Pennsylvania S1 Duplex 6-4-4-6: Tractive Effort 71,900 lbs - (FA) Factor of Adhesion 3.92

Pennsylvania Q2 Duplex 4-4-6-4: Tractive Effort 100,800 lbs - (FA) Factor of Adhesion 3.58

------------------

Learnings: In responding to RME

"...a great long discussion follows - which could be condensed into one brief but significant, metric: the factor of adhesion (FA)."

 You indicated in your last post that (FA) Factor of Adhesion was much clearer indication of the Duplex driver slip problem.   I feel that this comparison of the unreliability of (FA) to specifically disclose any clear conclusions significantly disproves this assumption.  Clearly the 1/2 vs 2/3 driver weight comparison gives a much clearer picture of the problem to the average reader.

The locomotive with the highest (FA) Factor of Adhesion 4.47 was the New York Central Niagara 4-8-4 and the lowest (FA) Factor of Adhesion 3.58 was the Pennsylvania Railroad Q2 Duplex 4-4-6-4 supposedly having solved the driver slippage issues.  The Union Pacific Big Boy 4-8-8-4 was also one of the lowest (FA) 4.02 Factor of Adhesion locomotives. 

The Pennsylvania T1 Duplex 4-4-4-4 had a (FA) Factor of Adhesion 4.13 - between - the Chesapeake & Ohio Allegheney 4.27 and Milwaukee F7 Hudson 4-6-4 (FA) Factor of Adhesion 4.10. 

Little or no obvious conclusion can be drawn about driver slippage owing to casual review of published statistical (FA) Factor of Adhesion numbers.

--------------

Aside from all this - what about the Pennsylvania Q2 Steam Turbine 6-8-6: Tractive Effort was 70,500 lbs which puts it above that of the New York Central Niagara 4-8-4 Tractive Effort of 61,500 lbs and Atchison Topeka & Santa Fe Northern 4-8-4 Tractive Effort of 66,000 lbs.  The Turbine does outweigh the these two famous engines by 80,000 lbs and 100,000 lbs respectively though. 

The (FA) Factor of Adhesion 3.70 for the Pennsy Turbine S2 must be considered similar to that of Diesel Electric locomotives because of the smooth torque transfer of the turbine is similar to that of the electric motor drive for the Diesel Electric which usually had a (FA) of 3.33 

Remarkably: the the Pennsylvaina Q2 Duplex 4-4-6-4 which had a (FA) Factor of Adhesion of 3.58 is astoundingly closer to that of the Diesel Electric 3.33 than any steam locomotive.  Likely the wheel slipage is an issue pertaining to another aspect of development.  

Further learnings: In reading Johnson's text he discusses the Tractive Effort situation further.  Specifically with the inability of existing theoretical engineering models to deal with power and tractive effort relating to boiler horsepower utilization and speed.

Johnson writes, "As the speed is increased, the available tractive force falls off until a point is reached at which the boiler can no longer supply the steam required by the cylinders at full stroke.  IF greater speed is desired, it is necessary to use the steam more efficiently, and this is accomplished by shortening the cut-off.  This procedure shortens the percentage of stroke during which steam is admitted to the cylinders, and during the balance of the stroke the expansion of the steam from boiler pressure towards atmospheric pressure does the work...It is evident that under these circumstances the tractive force that a locomotive can develop is dependent not only on the cylinder and driving wheel dimensions, but also on the steaming capacity of the boiler."

Poppet valve gear design was able to achieve steam cut-off rates that Walschaerts valve gear was never capable of.  I assume that is why New York Central and Pennsylvania Railroad were both experimenting with poppet valve design advantages and problems.  New York Central Niagara 4-8-4 engine 5500 was equipped with the poppet valve gear and Paul Kiefer the Chief Engineer for the railroad considered the NYC 5500 the most powerful ever built for the railroad.  Giving the NYC Niagara 4-8-4 an extremely high (FA) Factor of Adhesion of 4.47,

Likewise the Pennsylvania Railroad T1 Duplex 4-4-4-4 of similar poppet valve design developed the principle of steam distribution beyond what Paul Kiefer did by doubling the effective cylinder capacity!  Likely the power developed by this "low cut-off" steam distribution system took the T1's steam locomotive running performance at speed, and Tractive Effort at speed into undiscovered engineering areas - result WHEEL SLIPAGE AT SPEED! a continuing and re-occuring problem because of the power developed by "low cut-off" and high steam distribution cylinder capacity.

Was the T1 (FA) Factor of Adhesion of 4.13 really enough?  How many Duplex locomotives of this type or design were ever developed by any railroad anywhere in history?  I also wonder if the company test facility dynometer with steel wheel roller drive ever fully did, or ever was fully capable of testing these T1 performance (FA) Factor of Adhesion parameters at high loading and and under high power conditions.  In this capacity the T1 remains a remarkable engine - who did anything like it?  And so unequaled in railroad history!

Thats my considered opinion -

Doc 

 

 

 

 

 

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Posted by Firelock76 on Tuesday, January 10, 2017 6:01 PM

daveklepper

Glad to have what was saved, squirreled away in the Northumberland roundhouse and now at the PA Railway Museum.

 

Amen to that David!  As the old saying goes, "Don't cry because it's over, smile because it happened."

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Posted by daveklepper on Tuesday, January 10, 2017 8:40 AM

Glad to have what was saved, squirreled away in the Northumberland roundhouse and now at the PA Railway Museum.

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Posted by CSSHEGEWISCH on Tuesday, January 10, 2017 8:05 AM

When you consider that PRR was operated at a loss in 1946 (the N&W dividend payments covered PRR's dividend payment), it should be easy to explain why preservation of the past might be non-existent in the corporation's planning.  PRR's soul was pretty much owned by the wealthy families on the Main Line who expected that dividend and a decent stock price as their divine right.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by Miningman on Monday, January 9, 2017 10:47 PM

RME- Wanswheel wins with the 20 foot jump shot! 

Grand Central and Washington Union were in a similiar condition and did not end up in the swamps of New Jersey. Grand Central came close though. I believe you have mentioned you are a New Yorker so come on, you know better. I know you know better. It's a deep story with many levels to it. What did Saunders settle for out of court for his shenanigans...$7 million or so personally...big big dollars in the '70's.

Does anyone here have a simple chart showing PRR and NYC yearly bottom line losses (or profits, there were some) 1948-1968. 

Thanks for the great answers on the T1's and the 5550 Trust. It really should be a doable project. Hollywood elites blow that much on a single party at times. 

Did not know that there was a discussion within the Pennsy regarding saving the S1. Perhaps that decision was the "one decision" that really marked a turning point and signalled the end of the Pennsy's soul because it was pretty much all downhill from there. As far fetched and goofy as that sounds there is something, actually much, to be said for pride, integrity, symbolism, spirituality and philosophy..when you sell out for a few shekels you lose, and big time.  The S2 was already built, it was beautiful and represented a failure but a very brave and bold attempt ...it could have been kept, it meant something serious to the Pennsy at the time. It would be a marvel today, to look upon and know its story.  As for a T1 and a Q2, facing the bankers and their equipment trusts, well fine, but I'm keeping one of each on the roster, no big deal. Just one from each fleet. New expensive Diesels were on the new handy dandy GM monthly payment plan for eternity. Just like the rest of us And I still have my 1969 Chevy Malibu convertible ragtop with the bench seat and an AM radio...and an ashtray. It's who I am. ( runs fine, looks great, just for summer nowadays). Also a '73 Vette, a monster really that I bought new and a '82 Vette which is my S2 if you will. 

The Pennsylvania Railroad represented so many things, including the building of and the fabric of America itself. They diminished themselves and rejected this heritage. The "knowers" know. 

Can't seem to find the right words tonight.

Anyway ...while I'm at it saving the past ( as most of you know I firmly believe that too much was lost) I'm also nominating for preservation an 1) A-A set of Baldwin Centipedes 2) an A-B-A set of Baldwin Pennsy class Bp-20 Passenger Sharks 3) an A-B-A set of PA's, thinking NYC this time and 4) 2 nice back to back New Haven Alco DL109's, any paint scheme is fine. Of course it is understood a NYC Hudson and a Niagara. 

Got to prep up for classes tomorrow. G'nite. 

 

 

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Posted by Paul Milenkovic on Monday, January 9, 2017 10:21 PM

Two questions.

How was Stanier's "Turbomotive" in Britain "successful" in the way that the Pennsy S2 turbine was not?  I mean the Turbomotive wasn't successful in the sense that they built a fleet of them, but it wasn't popping staybolts either, was it?  And wasn't the multiple-nozzle turbine, creating a kind of "notched throttle" the inspiration for the S2, or did they go a different path?

Second question -- what is the problem with "overcylindering" a steam locomotive, that is, giving it more tractive effort than the adhesion can take?  The advantage of more cylinder capacity is that you can run it at lower cutoff and higher efficiency at speed?  As to the disadvantage, couldn't there be a throttle notch where at low speed and full gear, you instruct the driver, "Look, don't exceed this notch or you will slip the wheels"?

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by wanswheel on Monday, January 9, 2017 1:04 PM

RME

NOT any kind of crown-jewel majesty

RME
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Posted by RME on Monday, January 9, 2017 9:44 AM

Miningman
... Will the T1 Trust 5550 project incorporate these fixes right from the intial construction in the hopes they work out, or perhaps just some of them initially, the major ones which I am aware of, and see how it goes?

There was a great deal of discussion early on to 'get these points documented' and design potential fixes for them.  An important methodological issue is that the locomotive will be extensively modeled in several programs, and given extensive multiphysics testing, before significant amounts of actual construction money have to be allocated.  One point is to leave key parts of the design 'open' so that things like Deem conjugation can be installed if they prove necessary or desirable.

At least some of the reason for historical integrity in the design is to establish as far as possible the truth or error of the "railfan" assessment of the T1 as a dog and a failure, and by extension the duplex concept as an impossibly slippery and fundamentally flawed idea.  It is of course easy to design a conjugated duplex that does not share the design problems and implementation failures of the early T1 effort - for example, by conducting better training and crew assessments so that  crews called to run T1s would know how to run modern locomotives of this design correctly under the sort of running conditions PRR would require ... and, by extension, to provide a training protocol for engineers in the 21st Century to learn best practices and, by extension, how to handle a duplex with minimum difficulty.

 

How true to the as built T1's or any modifications later adopted by the Pennsy will the 5550 actually be? Will the welded frame rather than one piece cast affect anything. Especially performance...should be somewhat better, no? It is certain that externally it should be the same.

As noted, the externals, and the fundamentals of the running gear, will be kept as close to the 'evolved' versions as possible, with certain exceptions (some of which are intended to give better running conditions for excursion service).  The decision was made, early on, to have as much 'historical' T1 as possible, and that ruled out, for instance, things like the use of 'cheek plates' and side-acting independent brakes.  However, it is likely that the valve gear will be modeled on Franklin type B or "C" (with external drive to the cams, as on locomotive 5500), probably with the 'drive arm' type of shaft suspension rather than the heavy angle frame used on earlier Franklin RC installations, which will give 5550 a different external appearance.  (I think this is justifiable, as had the T1s remained in first-line service more locomotives would have been converted to type B-2 (the version of RC optimized to work with the 8-valve type A cylinder configuration) with the improved shaft arrangements worked out for type D.)  This also facilitates the installation of Deem conjugation if that becomes desirable, and eliminates the weight, cost, and complexity of the internal camboxes and derived motion.

The welded frame (likely a combination of lost-foam castings and fabrications) is expected to be both stiffer and lighter than original.  For reasons of code compliance alone the boiler will be all-welded and made of modern steel composition, which is already recognized to produce significant weight-saving and some leeway in locating auxiliaries on the locomotive; this will allow use of a different feedwater-heater arrangement (personally, I'd love to demonstrate how to build and maintain a historical Turbo-Inspirator setup, but that arrangement appears to have been originally installed more for weight-saving than operational effectiveness, and it has about the same charm for reliable operation that a rebuilt Winton 201A would for the Flying Yankee.  I suspect that a range of the 1948 improvements will be applied (which, again, is in keeping with likely PRR practice if the engines had been kept for first-line service) specifically including better alloys and finishing for the valves and their mountings.

I suspect there are better alloys for the Timken rods, including the current cerium-bearing formulations.  The rods, interestingly, will be made to exact historical dimensions, with bushings for the anticipated use of modern Timken equivalents for the rod roller bearings.  I expect that both the axle and rod rollers will outlast several sets of driver tires, especially if frequent dressing of the tread profiles is made.

 

 

Will there be some digital devices installed in the cab and throughout in various locations?

Yes, but they will be modular and removable, so that the engine can be operated in full "legacy mode" when desired. The one exception is that I don't expect the historical PRR cab signaling to be fully duplicated electronically unless specifically-earmarked fundraising for it is provided, as there's no operating benefit to be gained from it now.

My preference is to use a fixed harness for the various digital and electrical devices, as its visibility would be minimal and its presence would not compromise any of the 'historical fabric', but there are alternatives that are even less intrusive.  I happen to think that designing versions of the auxiliaries that can run on 220V AC power under logic-bus control makes sense for actual operation, but that is a decision to be made much closer to "run time".

The locomotive will be fully PTC compatible.  It made no sense to design it otherwise, whether or not there are present exceptions or grandfathering for steam locomotives.  Safety is safety, first, last, and always.

As an aside, I expect that the actual drivers on the locomotive when it reaches operational completeness will all be instrumented.  There has been some foon opinion expressed here and on some other forums that the cost of "instrumented wheelsets" far exceeds any practical budget.   I would ask whether people that have experience in building plasma-physics equipment are likely to lack either the engineering or fabrication skills needed to construct instrumented Boxpok driver sets, or the equipment appropriate to calibrate them and then derive meaningful data from the installation.  However, there is no question in my mind that all drivers, not just the main, would need to be extensively instrumented before any high-speed operation of the locomotive is made.  And the same likely goes for the lead and trailing truck wheels, and the lateral-accommodation mechanisms used in both trucks.

One topic still under discussion is the extent to which the locomotive will provide HEP-compliant power.  3463, for example, is intended to have a full implementation at 440V and perhaps at DC-link traction voltage, and the genset involved is a key part of the 'technology demonstration' behind Project 130.  While it would of course be highly valuable to have HEP capability on 5550, it is difficult to see where it should be packaged (as opposed to dedicated HEP generation in a separate car).  I suspect that decision will be made at a considerably later stage in specified detail design.

The S1, S2, a T1 and a Q2 should never have been scrapped but I understand the reasons and the pressure, along with the thinking of the day ...

Correspondence at the Hagley indicates just how much effort was made to preserve the S1, with the decision essentially coming down to the perceived importance of the scrap value at a time when PRR was showing a loss and incurring heavy cost for rapid dieselization.  The Q2 was essentially a 'win-the-war' locomotive, and once that war was over PRR could get just as good service (for how they ran peacetime freight trains) out of much-more-easily-maintained J1s.  I believe the same 'expedience' regarding equipment trusts applied to the Q2s that applied to the T1s; both classes "had to die" perhaps in the most embarrassing manner contrivable to get the bankers to release PRR from the ongoing heavy indebtedness that those locomotives represented.

The S2 as built rapidly demonstrated it was a remarkable flop.  It would have been highly interesting to see the 4-8-4 follow-ons that Westinghouse, at least, saw coming ... but you can assume that these would have had different gearing and turbine layouts, much better exhaust, and probably (in my opinion at least) arrangements to permit turbine rotor speed separate from driver rotational speed -- most likely some version of the Bowes drive that was considered for the V1, although other approaches (magnetorheologics for one) were possible in that era.  The idea of the S2 riveted boiler with All Those Popping Staybolts rapidly queered any particular enthusiasm for the direct-drive turbine as early as 1946, before the 'perfect storm' that led to new steam-locomotive design's rapid exit; the V1 was of course a much better locomotive for nearly any practical PRR purpose ... and the water-rate issues killed that.

Cripes, they even junked their crown jewel Penn Station ...

By the time Penn Station came down, it was euthanasia.  You may not remember what it was like to walk through in the early '60s -- I barely remember myself -- but it was NOT any kind of crown-jewel majesty, and this was before the era of 'easy money' for retro-historical architectural renovations.  Unlike the situation at GCT, the proven value of the air rights over Penn Station were immediate, massive, and of significant value to a rapidly-hemorrhaging PRR with very little interest in the passenger business at all.

(Interestingly enough, the original drawings for GCT clearly demonstrate that framing to support an office structure of over 20 floors was included in the design and construction of the concourse; the Breuer disaster that kicked off the organized Save Grand Central effort was to sit over the waiting room at the front.  Anyone from New York understands why the 'preserve the view down Park Avenue' argument was a crock by 1977...)

...and one more...how is the project coming along?

Nicely.  I encourage anyone to subscribe to their 'Trail Blazer' newsletter and to review the content of their site periodically.  Personally, I think the effort is fast approaching the point where a case can be made for 'interested parties' to put up substantial parts of the build cost, with reasonable assurance that both the knowledge and the professional management needed to complete the project successfully in all necessary respects can be provided.

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Posted by CSSHEGEWISCH on Monday, January 9, 2017 8:15 AM

kgbw49

Mining Man, keep watch for smoke on the horizon, because it is coming!

You have a lot more faith than I do.  As I see it, the trust is trying to raise several million dollars for what comes across as a giant engineering experiment that they might never be able to perform, assuming that this machine can actually be built.

 

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by Miningman on Sunday, January 8, 2017 10:50 PM

Very nice RME...having read through several different long threads on the forum in various places over the years and several more recent articles ( last 5-10 years) mostly technical in nature on the T1's, a great deal of useful information has come to light. It appears we know more now than we did a decade ago, especially along the lines of how to overcome problems.

So my question(s) to you is: Will the T1 Trust 5550 project incorporate these fixes right from the intial construction in the hopes they work out, or perhaps just some of them initially, the major ones which I am aware of, and see how it goes?  How true to the as built T1's or any modifications later adopted by the Pennsy will the 5550 actually be?

Will the welded frame rather than one piece cast affect anything. Especially performance...should be somewhat better, no? 

It is certain that externally it should be the same. Will there be some digital devices installed in the cab and throughout in various locations? 

There was still at least one still in Altoona in 1956 because there is a picture of it in a line, dead of course. Such a shame it was not hidden away somewhere or simply purchased by a museum or deep pockets. The S1, S2, a T1 and a Q2 should never have been scrapped but I understand the reasons and the pressure, along with the thinking of the day. Cripes, they even junked their crown jewel Penn Station. 

...and one more...how is the project coming along? I recently ordered the Baldwin print from them. 

RME
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Posted by RME on Sunday, January 8, 2017 9:34 PM

Dr D
If the Pennsy T1 Duplex 4-4-4-4 had been designed with greater weight on the drive wheels - COULD substancial repair costs to the highly successful poppet valve design have been adverted.

And a great long discussion follows - which could be condensed into one brief, but significant, metric: the factor of adhesion (FA).  This is normally expressed as the ratio of weight on drivers to TE, and the general 'rule of thumb' in American practice was that this should be around 4.

The T1 was notable for starting out with a remarkably high FA, which in fact was increased still more (!) in development.   (Compare this with the very low effective FA for the 70" drivered N&W J class.)

Repair costs to the poppet valves were largely related to design of the valve spools and insufficient return-spring tension.  Both had been addressed in principle in the 1948 engineering revisions; as it turned out, with the change to use of diesels on the first-rank trains, only the changed valve springing was implemented.  Personally, I have little doubt that the combination of centrifugal casting and alloy revisions to the type A valves would have reduced or eliminated valve breakage or warping as a cause of road problems. 

... Whereas the piston driven steam locomotive is subject the cyclic transmission of its power increasing and decreasing with every piston stroke eight times per revolution of each axle. A good strong piston thrust can likely break traction resulting in wheel slipage and loss of traction control - thus the requirement of significant portion of engine weight to rest upon the locomotive drive wheels.

Note that this situation is more related to early cutoff, and to short stroke in T1s, than to necessarily 'peaky' torque.  (If you overlay the torque contributions of the four events per rotation in a typical 2-cylinder DA locomotive, as Wardale did at 15-degree increments, you will see that the nominal torque peakiness measured at the driver rim does not need to be excessive.)  This is why it is idiocy to start hooking up the reverse within a few "beats" of starting when there's even a suspicion of poor adhesion conditions: it's thermodynamically 'best' to drive on the reverse with the throttle wide open, but the torque becomes peakier even as the peaks become higher (and if, as on the T1s, the torque becomes such as to prolong the angular slip past the 'next' torque peak, things can get out of hand very quickly right up to the engine's ability to make and flow steam...)

 

Could those small 69" wheels would really spin with those massive roller bearing rods at those speeds it was designed to run?

I am tempted to ask 'why not?' considering that locomotives that run at much higher speed have lower drivers, and the roller-bearing rods on the S2 were in perfect rotational balance (no reciprocating motion or thrust).  The DR class 19 motor locomotive also had remarkably small drivers but apparently had little or no trouble spinning up to 110+mph speeds.

 

... considering the trauma the railroad experienced with poppet valve gear damage one wonders why they didn't lighten the spring loading of the front and rear trucks to transfer more of the total engine weight on the drive wheel sets?

A version of this approach was, in fact, an early part of the response to lead-engine slipping.  The original lead-truck lateral accommodation setup had the characteristic (shared with many another high-speed locomotive!) of lifting the frame as part of obtaining non-spring restoring force.  This, PRR thought, made the lead engine even with equalized suspension more amenable to slip.  Note however that the 'cure' didn't fix the important parts of the disease.

Note also that you can't just go increasing the weight on drivers in a cavalier fashion - the side of the railroad that manages the trackwork and bridges will have something to say to you, and the increased treadwear and other factors that go along with higher driver loading will make your 'numbers' look worse.  Much better to take positive action to keep slips from propagating, and ideally train crews how to get 'the most' out of a short-stroke locomotive with modern steam distribution.

 

Possibly the driver axle bearing sets or the wheels themselves were not designed for such greater weight loadings.

Timken roller bearings in cannon boxes?  Boxpok drivers?  Not capable of absorbing an extra few thousand lb?

 

Since one of the two sets of drivers slipping was part of the problem one wonders why two throttle setups were not used - one for the front half of the locomotive and one for the rear?

Same reason Jesus wasn't born in a hotel: there's no room for two throttles, even with air actuation, in the header area. 

Now, having said that, it's very clear that separate throttles (and separate valve-gear adjustment) would be useful on a T1, and indeed if we make the assumption that the forward engine is 'slipperier' it becomes relatively easy to incorporate devices called Wagner throttles (see the ACE3000 patent where they are misspelled as "Waggoner" throttles) in the four tracts going to the poppet valves.  These are basically fluidic-amplifier servo controlled, so very large openings can be reliably and very quickly modulated; on the T1 they would serve to trim the 'throttle' admitted steam down to where the forward engine would not have a higher propensity to slip, and of course they can close down and then reopen to 'original' position very quickly, which is what is needed to arrest a slip and then go back rapidly to making as high a TE as you can (for starting and for acceleration).

There are also several ways of implementing quick-acting traction control on one engine, which I have described previously; the one that involves the least 'jiggering' uses a split independent foundation to apply driver brakes selectively by engine as well as to the locomotive 'as a whole'.

Likely the booster engine idea first used on T1 6111 should have been retained on the rest of the fleet of engines for starting purposes as this was a high slippage condition. Station maneuvers in slippery conditions often rendered the T1 duplex almost unmanagable. Likely cheapskate Pennsy known for years as poorly equipping its locomotive fleet opted out on the inclusion of expensive booster engines that would have helped this - "extremely high speed" design of the T1 locomotive.

I, too, remain surprised that boosters weren't taken up as an 'answer' to T1 slipping, but it is true that all the way through 1948 they weren't seen as the right answer, even to the point that a fabulously invasive technique for installing piston valves was worked up and actually installed ... on a locomotive that did not get a booster.

Part of the situation likely involves the reason why the T1s had those funky Turbo-Inspirators instead of more reliable FWHs: overall weight, and weight distribution.  A typical Franklin booster on that short-wheelbase truck would increase the effective polar moment , put even more weight on the rear of the locomotive chassis, involve more steam and control lines, and still be useful only for slow-speed operations.

The Lewty booster is a better example all around of what the T1 needed: light, high-speed drive at the truck, and good positive-displacement power carried as sprung mass.

 

what a wonderful locomotive the Pennsy Turbine S2 6-8-6 appears to have been. From an engineering standpoint it looks to be an extremely different steam locomotive than regular conventional piston driven steam engines. In this Pennsy grouping - the famous turbine is really a separate engineering study completely unto itself. In my opinion it was among the most beautiful steam engines Pennsy ever built. I cannot believe they had the courage to build it - then I cannot believe they had the courage to scrap it!

If you could read the correspondence on this locomotive after the middle of 1946 or so, you might change some of your opinion on the thing.  Whether or not you agree as I do that the V1 configuration made a better turbine locomotive, there's little doubt that PRR considered the S2 a 'locomotive of the future' ... right up to the point things started going wrong.  In my opinion, the day it started stripping staybolts (a thing that it proved repeatedly good at!) was the day the bloom started coming off the rose.

Note that in a 1948 Westinghouse catalog you can plainly see 4-8-4 turbine locomotives depicted, and I am reasonably certain there were roads that could have found them interesting (albeit only with something like a Bowes drive that could get rid of the colossal steam demand at starting and low speed).  I think a solution for the need to provide very large exhaust plenum volume for low turbine backpressure, but also the problem that such a large volume makes for enormous draft issues at high exhaust mass flow, could be found -- but it certainly wasn't on 6200 as built, and it's instructive that no attempt was made when the problems started to rear their heads.

The huge "American Railroads" Words Fair display engine - the Pennsy S2 experimental Duplex looms LARGER and LARGER in my mind than it ever appeared to me before. It had such massive speed potential - featuring Duplex drive through 84 inch wheels with simple Walscharts valve gear construction. And! the length - all that length! - on a rigid frame! The size of a of Union Pacific articulated Big Boy - which was the largest steam locomotive ever built - I can hardly imagine the courage it took to have the S2 built! Just unbelievable!

Look here, how many times do I have to tell you, the 6100 is the S1.  The 6-4-4-6 duplex is the S1.  It's the TURBINE we were just discussing that is the S2.

 

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Posted by kgbw49 on Saturday, January 7, 2017 1:48 PM

Mining Man, keep watch for smoke on the horizon, because it is coming!

 

 

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Posted by kgbw49 on Saturday, January 7, 2017 1:45 PM

Dr D, I just wanted to say I really enjoyed reading your comparative analysis.

Yes, the mighty diesel ended up conquering reciprocating steam. But that doesn't make the steam locomotive any less grand of a human endeavor.

They were brilliant and amazing men doing incredible things with the technology of the time.

To borrow a few lines from a well-known Broadway play...

Don't let it be forgot
That once there was a spot
For one brief shining moment that was known
As Camelot.

The power and majesty of the United States railroad steam locomotives of the 1920s, 1930s and 1940s was, and is, most worthy of not only remembrance, but of revival and continuance at every opportunity!

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Posted by daveklepper on Saturday, January 7, 2017 1:03 PM

Miningman, I am with you all the way.   Except that I would take a GG-1 in operation as a TEMPORARY substitute.   (And of course Arab - Israeli peace.)

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Posted by Miningman on Friday, January 6, 2017 11:35 PM

2 Years ago, on a cold and dark Friday night, living alone, I suffered a serious heart failure and flash pulmonary edema, after several fading fast attempts at dialing 911, got through, explained calmly, ran outside bouncing off the side of the house all the way and promptly dropped dead as a doorknob at the top of the driveway. 

Woke up in a delerium in Saskatoon, 600km away in a hospital bed. One month.

Since then 3 things have kept me alive. 1) My students, they keep me young and hopeful and they need me. 2) The myriad of pills I take every day 3) The thought, desire and hope that one day I could see a T1 yet again steamed up and in full glory.

I'm not kidding. 

An E7...meh...thats nice, kinda, but it ain't gonna keep me alive. 

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Posted by Dr D on Friday, January 6, 2017 10:45 PM

Ok guys - I get it - you believe in the great myth that was the EMD E7 diesel electric locomotive - and this post is about "THE MYTH AND THE MYSTERY BEHIND THE PENNSY DUPLEX T1." 

I might remind you that the EMD E7 today is just as dead an issue as the Pennsy Duplex is - in fact preparations are afoot to build a new T1.  Here is the mystery and the magic? - that anyone would go to such expense!  Truely the Pennsylvania Railroad should have preserved a T1 Duplex.

-----------------------

THE PENNSY DUPLEX AND WEIGHT ISSUES:

If the Pennsy T1 Duplex 4-4-4-4 had been designed with greater weight on the drive wheels - COULD substancial repair costs to the highly successful poppet valve design have been adverted.  

The other giant S1 "experimental" Duplex 6-4-4-6 had been fitted with regular retro low speed design Walschaerts piston valve gear. 

Considering its operational speed the Q2 Duplex "freight" engine 4-4-6-4 was also given Walschaerts valve gear in its design decision - but also had significantly greater weight on the drive wheels! - this was one factor attributed to successfully eliminating much of the damaging Duplex wheel slipage problem. 

------------------------ 

WEIGHT OF THE ENGINE AND WEIGHT ON THE DRIVE WHEELS this determines partially the traction given a locomotive and resultant potential to slip the drive wheels under power.

Pennsylvania S1 Duplex 6-4-4-6 - drive wheel diameter 84" - total engine weight 608,200 lbs - weight on drive wheels 281,400 lbs.

Pennsylvania T1 Duplex 4-4-4-4 - drive wheel diameter 80" - total engine weight 497,200 lbs - weight on drive wheels 268,200 lbs.

Pennsylvania Q2 Duplex 4-4-6-4 - drive wheel diameter 69" - total engine weight 621,100 lbs - weight on drive wheels 386,000 lbs.

-------------------------

Lets examine a few other famous engines also:

New York Central Hudson 4-6-4: drive wheel diameter 79" - weight of locomotive 265,500 lbs - weight on drive wheels 201,800 lbs.

New York Central Niagara 4-8-4: drive wheel diameter 79" - weight of locomotive 471,000 lbs - weight on drive wheels 275,000 lbs.

Atchison Topeka & Santa Fe Northern 4-8-4: drive wheel diameter 80" - weight of locomotive 510,000 lbs - weight on drive wheels 294,000 lbs.

Milwaukee Road F7 Hudson 4-6-4: drive wheel diameter 84" - weight of locomotive 365,500 lbs - weight on drive wheels 216,000 lbs.

------------------------------------

To put the Pennsy Duplex locomotives in something of a larger framework compare them to these engines.

Chesapeake & Ohio Allegheney 2-6-6-6 articulated freight engine:  drive wheel diameter 67" - weight of engine 751,800 lbs - weight on drive wheels 504,000 lbs.

Union Pacific Big Boy 4-8-8-4 articulated freight engine: drive wheel diameter 68" - weight of engine 772,000 lbs - weight on driving wheels 545,000 lbs.

Pennsylvania Railroad S2 steam turbine 6-8-6 an all time unique design passenger engine: drive wheel diameter 68" - weight of locomotive 580,000 lbs - weight on drive wheels 260,000 lbs.

---------------

WEIGHT ON WHEELS in context -

700,000 lb engines were the - Chesapeake & Ohio "Allegheney" and Union Pacific "Big Boy" - this is not surprising. 

(Consider that the firebox size Pennsy S1 experimental "Duplex" 6-4-4-6 and S2 experimental "Turbine" 6-8-6 were the same as these 700,000 lb locomotives built on a much smaller engine mass of 600,000 lbs.)

600,000 lb engines were the - Pennsy Q2 mass produced freight Duplex 4-4-6-4, Pennsy S1 experimental "Duplex" 6-4-4-6, Pennsy S2 experimental "Turbine" 6-8-6 - this surprises me as I never believed the turbine was that massive.

500,000 lb engines were the - Pennsy T1 mass produced "Duplex" 4-4-4-4, the Atchison Topeka & Santa Fe "Northern" 4-8-4 and on the slightly lighter side at 471,000 lbs the New York Central "Niagara" 4-8-4. 

400,000 lb engine was the - Milwaukee Road F7 "Hudson" 4-6-4.

300,000 lb engine was the - New York Central "Hudson" 4-6-4.

---------------------

PROPORTIONAL ENGINE WEIGHT TO WEIGHT ON DRIVING WHEELS - the critical measurement for traction.

LIGHT WEIGHT ON DRIVE WHEELS - about 1/2 weight of engine resting on the drivers:

Pennsy experimental S1 "Duplex" 6-4-4-6 - 608,200 / 281,400 lbs

Pennsy production poppet valve T1 "Duplex" 4-4-4-4 - 497,200 / 268,200 lbs

Milwaukee F7 "Hudson" 4-6-4 speedster - 365,500 / 216,000 lbs

Pennsy experimental S2 steam turbine 6-8-6 - 580,000 / 260,000 lbs

-----------------------------

HEAVY WEIGHT ON DRIVE WHEELS - about 2/3 weight of engine on drivers:

Pennsy Q2 "Duplex" freight locomotive 4-4-6-4 - 621,100 / 386,000 lbs 

New York Central "Hudson" 4-6-4 - 265,500 / 201,800 lbs

New York Central "Niagara" 4-8-4 - 471,000 / 275,000 lbs 

Atchison Topeka & Santa Fe "Northern" 4-8-4 - 510,000 / 294,000 lbs

Chesapeake & Ohio "Allegheney 2-6-6-6 - 751,800 / 504,000 lbs

Union Pacific "Big Boy" 4-8-8-4 - 772,000 / 545,000 lbs.

----------------------------------

 Pennsy S2 experimental is just a Reference locomotive here - in the above comparison the Pennsy S2 experimental Steam Turbine 6-8-6 falls under different engineering parameters because the smooth torque of the turbine drive is constant - giving steady driving force to the engine.   Whereas the piston driven steam locomotive is subject the cyclic transmission of its power increasing and decreasing with every piston stroke eight times per revolution of each axle.  A good strong piston thrust can likely break traction resulting in wheel slipage and loss of traction control - thus the requirement of significant portion of engine weight to rest upon the locomotive drive wheels. 

-------------------

DRIVE WHEEL DIAMETER - traditionally divided between "freight locomotives" with small wheels to improve torque transfer to the rail and large diameter drive wheels which revolve a greater distance with each turn favored by "passenger locomotive" design for running at speed.

84" drivered engines were - Pennsy experimental "Duplex" 6-4-4-6, and Milwaukee F7 "Hudson" speedster.

80" drivered engines were - Pennsy mass production T1 "Duplex" 4-4-4-4, and Atchison Topeka & Santa Fe "Northern" 4-8-4 desert racers.

79" drivered engines were -  New York Central "Hudson" 4-6-4 and New York Central "Niagara" 4-8-4.

69" drivered engines were - Pennsylvania mass produced Q2 Duplex freight engine - famous for developing over 8000 horsepower.  Also, Pennsylvania experimental S2 "turbine" - this is a surprise as the sight of those wheels and drive rods running over 110 mph with smooth turbine drive would have been something special to witness - Could those small 69" wheels would really spin with those massive roller bearing rods at those speeds it was designed to run? 

68" drivered engine was - Union Pacific "Big Boy" articulated and largest steam freight locomotive ever built - with 80 mph maximum speed - although never used as passenger power in the past, one is today being restored for just such passenger power use!

67" drivered engine was - Chesapeake & Ohio "Allegheney" articulated and also candidate for highest horsepower locomotive ever built.  Some units of this mass produced locomotive were equipped for passenger train use.

--------------------------

LEARNINGS - yes the Pennsy T1 Duplex was "light of foot" - remarkably so - considering the trauma the railroad experienced with poppet valve gear damaged one wonders why they didn't lighten the spring loading of the front and rear trucks to transfer more of the total engine weight on the drive wheel sets?  Possibly the driver axle bearing sets or the wheels themselves were not designed for such greater weight loadings.

Since one of the two sets of drivers slipping was part of the problem one wonders why two throttle setups were not used - one for the front half of the locomotive and one for the rear?  Airliner design and ship design often have individual throttles for each engine set up.  In this fashion the free spinning set could be throttled back without shutting down the entire locomotive. 

Likely the booster engine idea first used on T1 6111 should have been retained on the rest of the fleet of engines for starting purposes as this was a high slipage condition.  Station manuvers in slipery conditions often rendered the T1 duplex almost unmanagable.  Likely cheepskate Pennsy known for years as poorly equipping its locomotive fleet opted out on the inclusion of expensive booster engines that would have helped this - "extremely high speed" design of the T1 locomotive.  Thats my take on it! 

--------------------------

Also - what a wonderful locomotive the Pennsy Turbine S2 6-8-6 appears to have been.  From an engineering standpoint it looks to be an extremely different steam locomotive than regular conventional piston driven steam engines.  In this Pennsy grouping - the famous turbine is really a separate engineering study completely unto itself.  In my opinion it was among the most beautiful steam engines Pennsy ever built.  I cannot believe they had the courage to build it - then I cannot believe they had the courage to scrap it!

----------------------------

The huge "American Railroads" Words Fair display engine - the Pennsy S2 experimental Duplex looms LARGER and LARGER in my mind than it ever appeared to me before.  It had such massive speed potential - featuring Duplex drive through 84 inch wheels with simple Walscharts valve gear construction.  And! the length - all that length! - on a rigid frame!  The size of a of Union Pacific articulated Big Boy - which was the largest steam locomotive ever built - I can hardly imagine the courage it took to have the S2 built!  Just unbelievable! 

- and does the Keystone state still sire such thinkers and builders today!  For America's sake I certainly hope so.

Doc  

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Posted by Paul Milenkovic on Friday, January 6, 2017 10:04 PM

schlimm
 
CSSHEGEWISCH

 

 
Dr D

Both Pennsy engines and the awsome S2 Turbine 6-8-6 needed development time to achieve their full potential and were never given the chance - because of this they were in some respects partially eclipsed by more conservative and less radical locomotives of equivalent fame.  

- Doc

 

 

They were eclipsed by what was considered a radical design on PRR, diesel-electric locomotives.  The pair of E7A's that were assigned to the "Red Arrow" were getting substantially better monthly mileages than the T1's.  High-speed performance looks flashy, but it doesn't mean too much if the locomotive spends an inordinate amount of time between runs being serviced and maintained.

 

 

 

Exactly!!  In the NFL, a key concept is "availability" --  if you are oft injured or, in some experimental steamers' cases, laid up in the backshop, fancy stats don't matter so much.  

 

It appears that the NYC Niagara and the N&W J class weren't simply regarded as fancy locomotives but rather as part of a system, which included the maintenance procedures to keep them out on the road turning miles.  It seems that the T1 was put together for high performance, with everything else about them -- training crews as to their performance characteristics, setting up shops to handle them, and so on, were an afterthought.

One of the excuses is that the Pennsy had lost the touch with developing new steam locomotive types and everything that goes with them.  That had put a lot of money and effort into partial electrification in the 1930s giving a lot of surplus steam locomotives and little need to update their designs until the mid 1940s.

Another excuse is that the Pennsy way was to introduce a design and "work the bugs out" through extensive testing, a process that was rushed with the T1.

But to the extent that the Niagara was a "success" and the T1 a "failure", all of these locomotives had a short service life and were rapidly replaced by Diesels.  Not only was steam on the way out, passenger service was also on the way out, and you could say that the Pennsy was on the long slide to being the Penn Central.

The poppet valves didn't help.  The legend goes that the (largely unauthorized) 100 MPH+ running of the crews damaged the poppet valves or their drive cams, and servicing those valves practically required taking the whole locomotive apart.  Think of the 4-6-8 valved Cadillacs or some other fancy car offerings of the 1970s and 80s that didn't hold up well in service.

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by schlimm on Friday, January 6, 2017 6:30 PM

CSSHEGEWISCH

 

 
Dr D

Both Pennsy engines and the awsome S2 Turbine 6-8-6 needed development time to achieve their full potential and were never given the chance - because of this they were in some respects partially eclipsed by more conservative and less radical locomotives of equivalent fame.  

- Doc

 

 

They were eclipsed by what was considered a radical design on PRR, diesel-electric locomotives.  The pair of E7A's that were assigned to the "Red Arrow" were getting substantially better monthly mileages than the T1's.  High-speed performance looks flashy, but it doesn't mean too much if the locomotive spends an inordinate amount of time between runs being serviced and maintained.

 

Exactly!!  In the NFL, a key concept is "availability" --  if you are oft injured or, in some experimental steamers' cases, laid up in the backshop, fancy stats don't matter so much.  

C&NW, CA&E, MILW, CGW and IC fan

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Posted by Paul Milenkovic on Friday, January 6, 2017 3:40 PM

Dr D

 

The T1 duplex although set up with running gear and steam distribution as the ultimate high speed passenger engine produced in mass numbers, its actual firebox grate and size were smaller than the NYC famed "Niagara" and Santa Fe "Northern" and smaller than the Milwaukee F7 high speed "Hudson."

 

 

Smaller grate and firebox?  That is the whole idea, of this . . . machine, you know?

https://www.youtube.com/watch?v=2yfXgu37iyI

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by Miningman on Friday, January 6, 2017 8:26 AM

Nice work and summation Dr D. Handy little reference. 

At least we had that glimpse and PRR tried. However... the FIX was in. 

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Posted by CSSHEGEWISCH on Friday, January 6, 2017 8:14 AM

Dr D

Both Pennsy engines and the awsome S2 Turbine 6-8-6 needed development time to achieve their full potential and were never given the chance - because of this they were in some respects partially eclipsed by more conservative and less radical locomotives of equivalent fame.  

- Doc

They were eclipsed by what was considered a radical design on PRR, diesel-electric locomotives.  The pair of E7A's that were assigned to the "Red Arrow" were getting substantially better monthly mileages than the T1's.  High-speed performance looks flashy, but it doesn't mean too much if the locomotive spends an inordinate amount of time between runs being serviced and maintained.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by Dr D on Friday, January 6, 2017 3:54 AM

Just How Big?

The S1 Pennsylvania Duplex 6-4-4-6 and T1 4-4-4-4.  How did they compare to the steam power of the age - specifically?

-------------------

Firebox dimensions - Grate area - Combustion chamber length: this is where the power comes from.

S1 duplex 6-4-4-6:  firebox 198"x96" with combustion chamber of 113" and grate area of 132 sq feet.

T1 duplex 4-4-4-4:  firebox 138"x96" with combustion chamber of 84" and grate area of 92 sq feet.

------------------------

Lets examine a few other famous engines also:

New York Central, Hudson 4-6-4: firebox 130"x90" with combustion chamber of 43" and grate area of 81.5 sq feet.

New York Central, Niagara 4-8-4: firebox 151"x96" with combustion chamber of 81" and grate area of 101 sq feet.

Atchison, Topeka & Santa Fe, Northern 4-8-4: firebox 144"x108" with combustion chamber of 64" and grate area of 108 sq feet.

Milwaukee Road, F7 Hudson 4-6-4: firebox 144"x96" with combustion chamber of 45" and grate area of 96.5 sq feet.

-----------------------

To put the Pennsylvania Railroad S1 duplex 6-4-4-6 to something of a larger framework compare it to these engines.

Chesapeake & Ohio, Allegheney, 2-6-6-6 articulated freight engine: firebox area 180"x108" with a combustion chamber of 118" and grate area of 135.2 sq feet.

Union Pacific, Big Boy, 4-8-8-4 articulated freight engine: firebox 235"x96" with a combustion chamber of 112" and grate area of 150.3 sq feet.

Pennsylvania Railroad, Duplex Q2, 4-4-6-4 all time highest horsepower freight engine: firebox 162"x108" with combustion chamber of 124" and grate area of 121.7 sq feet.

Pennsylvania Railroad, S2 steam turbine  6-8-6 all time unique design passenger engine: firebox 180"x96" with combustion chamber of 120" and grate area of 120 sq feet.

-------------------

"Big" in context!  -

The S1 Duplex 6-4-4-6 was a high speed passenger engine on the equivilent size of the articulated Union Pacific "Big Boy" and Chesapeake and Ohio "Allegheney" something never duplicated by any railroad.

The T1 duplex although set up with running gear and steam distribution as the ultimate high speed passenger engine produced in mass numbers, its actual firebox grate and size were smaller than the NYC famed "Niagara" and Santa Fe "Northern" and smaller than the Milwaukee F7 high speed "Hudson."

Pennsy T1 Duplex 4-4-4-4 like its famed Q2 partner 4-4-6-4 freight engine were relying on steam distribution technology of the age to achieve their ultimate performance numbers.  The Q2 with its outstanding record of freight power and T1 with its outstanding if unrecorded speed record.

Both Pennsy engines and the awsome S2 Turbine 6-8-6 needed development time to achieve their full potential and were never given the chance - because of this they were in some respects partially eclipsed by more conservative and less radical locomotives of equivalent fame.  

When it comes to the stuff of dreams though - The Pennsylvania Railroad lives large and took us on a trip un equalled in railroad locomotive history - the mythological journey in steam - of what could have been? - truely written and painted forever large as "American Railroad Glory!"  Is it any wonder the T1 trust wants to reproduce a long lost T1 duplex!

-----------------

- Doc

 

 

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Posted by Firelock76 on Thursday, January 5, 2017 5:35 PM

RME, according to Chris Zarhrt's superb article on the Loco Valve Pilot in the Classic Trains special "Steam Glory 3"  the Pennsylvania RR wasn't one of the Valve Pilot users.

They were, as follows:  Atchison, Topeka & Santa Fe, Atlantic Coast Line, Bessemer & Lake Erie, Boston& Maine, Central Railroad of New Jersey, Central Vermont, Denver & Rio Grande Western, Maine Central, New Haven, New York Central, New York, Ontario & Western, St. Louis-San Francisco, Savanna & Atlanta, Southern Pacific, Union, Western Maryland, Wheeling and Lake Erie.

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