Jones1945I have a question about PRR S1's FA (Factor of adhesion). According to Wiki: "Starting tractive effort calculated in the usual way (85% mean effective pressure) comes out 76,400 lbf (340 kN), but the engine used 70% limited cutoff (presumably to increase port openings at short cutoff) so the railroad claimed a correspondingly lower tractive effort.", Does that mean S1's TE never reached 76,400 lbf during normal operation? Was there any mechanical device to allow the crews increasing the cutoff to 85% for maximum TE?
These are two vastly different things. The '85%' is a convention in the formula that corrects for pressure drop from nominal (safety-valve pop) boiler pressure to the actual pressure present at the cylinders to make power. The limited cutoff is a characteristic of the valve gear that closes the inlet ports to steam "early" even when the valve-gear mechanism is set to full gear, thereby forcing expansive working all the time.
Yes, there were approaches to get around the issues of limited cutoff when starting, the most familiar being slot ports or 'Weiss' ports as Porta liked to call them. Remember that even with limited cutoff and long-lead long-travel valves, the valve heads and rings still run the full stroke of the piston valve. Providing some very thin slots communicating to throttled steam relatively early in the stroke gives some amount of admission corresponding to a steam edge earlier in the valve stroke -- but restricted by the relatively poor flow, wire-drawing effects, etc. of steam through the small aperture as rotational speed came up.
Compare to S1, N&W Class J had a much higher TE and lower FA but they were doing just fine, I don’t understand why PRR didn’t max out S1’s potential during the War.
Part of this involves N&W actually driving the locomotives correctly, something it would appear that too many PRR engineers had little interest in doing too much of the time. There's always a problem with railroads wanting to get full rated power out of any locomotive as much of the time as possible, with one usual result (with steam locomotives) being to assign train consists that under many conditions will be difficult to start without care. The low FA of the Glaze-balanced J would require very careful handling at low speed, although several factors of the design would make the almost-inevitable slips easier to recover from than, say, in the S1 or T1 as built.
The problem with the S1 towing very large consists is that this would exacerbate an already serious issue with one of the engines breaking loose and slipping either at low speed or high (two different sets of physical conditions). This would be a formula for disaster without some 'hardware' method of trimming throttle admission to the two engines separately, with starting from many stations being a protracted agony in anything less than perfect conditions, and high-speed running being a constant and ultimately neurotic attention to incipient high-speed slips that might start over little more than a bad joint or harmonic.
Note that this is very different from getting the locomotive to pull that number of cars, or (in my opinion, reasonably) using a terminal switcher to assist in starting ridiculously long heavy consists, perhaps after having to break long consists just to get them into intermediate stations within platform length. instead of putting a booster with all its weight and efficiency issues on the S1 itself. There is little doubt that the S1 could operate a train of tremendous length at some 'balancing speed', albeit not very happily. But outside the performance envelope of 84" Atlantics with short stroke and high pressure under a common boiler...
Imagine if S1 could tow a named train (eg.14 cars) plus its section (eg.9-10 cars) at the same time, that would saved at least 2 K4s and 4 crews! [/quote]
Miningman Except the S1 was limited as to where it could run so when you get to Crestline you have this monster train, so now what do you do?... and need the crews and K4's there anyways. Pay me now or pay me later.
Miningman Between the Centipedes, the Bp20 passenger Sharks, the regular Sharks, the FM opposed piston offerings, the PA1's and other assorted disasters a whole ton of money went down the drain with a lot of headaches along the way. People keep stating " war weary worn out steam locomotives", but heck, Altoona rebuilt them good as new anytime, quickly, efficiently and skillfully. I think perhaps keep the steam and use it up, buy Diesel swithchers ok, let things sort themselves out and then go all in same as N&W did. Armchair stuff but that was rather easy to see.
Jones 3D Modeling Club https://www.youtube.com/Jones3DModelingClub
Except the S1 was limited as to where it could run so when you get to Crestline you have this monster train, so now what do you do?... and need the crews and K4's there anyways. Pay me now or pay me later.
As for the Centipedes, well they had 2 moments of glory...10 minutes after they rolled off the line and outside for the official photo and when they were glamourized in the painting.
The depiction is reminiscent of a Roman Centurian or Patton slicing forward to Berlin.
Between the Centipedes, the Bp20 passenger Sharks, the regular Sharks, the FM opposed piston offerings, the PA1's and other assorted disasters a whole ton of money went down the drain with a lot of headaches along the way. People keep stating " war weary worn out steam locomotives", but heck, Altoona rebuilt them good as new anytime, quickly, efficiently and skillfully. I think perhaps keep the steam and use it up, buy Diesel swithchers ok, let things sort themselves out and then go all in same as N&W did. Armchair stuff but that was rather easy to see.
Hi All,
I have a question about PRR S1's FA (Factor of adhesion). According to Wiki: "Starting tractive effort calculated in the usual way (85% mean effective pressure) comes out 76,400 lbf (340 kN), but the engine used 70% limited cutoff (presumably to increase port openings at short cutoff) so the railroad claimed a correspondingly lower tractive effort.", Does that mean S1's TE never reached 76,400 lbf during normal operation? Was there any mechanical device to allow the crews to increase the cutoff to 85% for maximum TE?
Compare to S1, N&W Class J had a much higher TE and lower FA but they were doing just fine, I don’t understand why PRR didn’t max out S1’s potential during the War. Imagine if S1 could tow a named train (eg.14 cars) plus its section (eg.9-10 cars) at the same time, that would be saved at least 2 K4s and 4 crews!
Best regards, Jones
It was a publicity pic of Martin Clemens’s ambitious dieselization plan for PRR’s Blue-ribbon fleet in 1948, the pic was heavily touched up. There is a E7 version too.
It even illuminates the track it is on.
Overmod....Now, if you look at PRR slang carefully enough, you'll see that 'snapper' was not just a regional term for helper service -- PRR had both 'helpers' and 'snappers' and they were not just distinguished by their location in a consist (although that is functionally important).
The largest, heaviest and most expensive "helper" the PRR ever purchased. It was supposed to perform as good as GG1, the preferred engine of the Blue-Ribbon Fleet. Its size fitted PRR’s taste, big enough to wow its rivals, but turn out they were one of the biggest flops in America Railroad History. (source: Railroad Museum of Pennsylvania, note the passenger cars were still carrying the FOM scheme)
daveklepperYes,routinely K4s were double-headed, especially Harrisburg-Pittsburg(h). (Often through to Crestline.) Never saw triple-heading though.
The double-heading was to create the effect of a single large road engine for very heavy Pullman consists (on the order of the 1000-ton train in the S1 spec), the rationale being the very large number of available locomotives (even more with the progression of the electrification). In fact it would be possible to doublehead a couple of E6 locomotives and save some costs ... as mirrored in the early planning and use of the O-class electrics or a bit later in the T1 design ... but the great 'standardization' was made in the Twenties, sized to perceived requirements then, and however much a mistake it was to do that, there were far more K4s available for 'fungible' use building passenger consists essentially greater than anything possible with Algerian-Garratt style articulateds. (And as noted, the crews would like All Those Extra Hours Every Hundred Miles On Every Train, too). Then the size of your available train becomes constrained by things like platform length or walk to the diner, not horsepower, except in one critical respect.
That respect being getting over the fixed maximum restriction on PRR, the grade over Gallitzin including Horse Shoe. This is where even the 'vanity cushion' of a twelve-coupled locomotive doesn't provide quite enough power to maintain road speed for the few miles of steep grade, and the third K4 would come into play.
Now, if you look at PRR slang carefully enough, you'll see that 'snapper' was not just a regional term for helper service -- PRR had both 'helpers' and 'snappers' and they were not just distinguished by their location in a consist (although that is functionally important). You need to distinguish what the extra TE and horsepower is meant to do. If you add locomotive power to enable a heavy train to make it 'over the hill', you have a helper. If you add locomotive power to enable a heavy train to make time 'over the hill' comparable to, or at least faster than, the train can make on either side, you have a snapper. And the selected class of snapper locomotive can't be, say, like the 2-10-2s used to drag diesel streamliners up the likes of Cajon; they have to be smooth-riding at the speeds expected.
So if snapping were desired, as on one of the 'first-class' trains, you might expect triple-heading, but only over certain divisions. Otherwise expect the fact of the double-heading to be able to maintain reasonable (albeit lower) speed, or the ability to traverse Horse Shoe without external helper, for less extreme or less demanding trains.
daveklepper They should have been envious of the Central's "Water-Level" route, It was that, more than superior motive power, that avoided double-heading on the Central. Yes,routinely K4s were double-headed, especially Harrsburg-Pittslbugh. (Often through to Crestline.) Never saw triple-heading though. Have any evidence?
They should have been envious of the Central's "Water-Level" route, It was that, more than superior motive power, that avoided double-heading on the Central.
Yes,routinely K4s were double-headed, especially Harrsburg-Pittslbugh. (Often through to Crestline.) Never saw triple-heading though. Have any evidence?
I read some articles mentioned about Triple-heading K4s, probably happened during World War II at the Horseshoe curves, but I never have seen any photographic or video evidence so far. Triple-heading after the war must be as rare as a double-headed T1 (jk).Btw, many think that PRR T1 was not welcomed by the crews because it replaced double-headed K4s; an operating arrangement which ensured their living hood.
In case you missed some "K4s action":
3rd rail The Pennsy guys were a bit envious of the NYC Hudsons just to their north... It took two, sometimes three, K-4's to get a passenger train across the Alleghenies, while the "Central" whisked along with a single J-3.. At 90 mph.. Now, John talked about running a T-1 from Crestline OH, To FT. Wayne IN hitting over 100 mph, but I can only imagine... Look at that line today. Weeds and rotten ties. Ah, what a shame....... Todd
WELL, While they were pretty to look at, I heard it from the "Horses Mouth" (John Crosby) who was an engineer on the Ft.Wayne line at the time, The S-1 was a total disaster. Slippery, and a real B!tch on curves. The T-1's were not any better.The T-1 would slip like hell starting a train. It was standard operating procedure to assign a pusher to get a T-1 led train out of Columbus Station. Best thing before the E-7's were the K-4's. Sure, dirty to work on, but sure-footed and could make the time. The Pennsy guys were a bit envious of the NYC Hudsons just to their north... It took two, sometimes three, K-4's to get a passenger train across the Alleghenies, while the "Central" whisked along with a single J-3.. At 90 mph..
Now, John talked about running a T-1 from Crestline OH, To FT. Wayne IN hitting over 100 mph, but I can only imagine... Look at that line today. Weeds and rotten ties. Ah, what a shame.......
Todd
WELL, While they were pretty to look at, I heard it fron the "Horses Mouth" (John Crosby) who was an engineer on the Ft.Wayne line at the time, The S-1 was a total disaster. Slippery, and a real female dog on curves. The T-1's were not any better.The T-1 would slip like hell starting a train. Best thing before the E-7's were the K-4's. Sure, dirty to work on, but sure-footed and could make the time. The Pennsy guys were a bit envious of the NYC Hudsons just to their north... It took two, sometimes three, K-4's to get a passenger train across the Alleghenies, while the "Central" whisked along with a single J-3.. At 90 mph..
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IIRC both unique 3-axle trailing and the leading truck had independent suspension, consists of coil and leaf springs. The same type of trucks was used on S2 which make both engines had an impressive and unique look, they ensured good ride quality too.
M636C ......Allen's own description is similar but less colourful. He did mention that two cast iron rail chairs in the curves had fractured... LMS Vice President Sir Ernest Lemon said, at the press lunch: "Of course, gentlemen, you will realise that we shan't need to do this kind of thing on every trip of the "Coronation Scot"; we were coming in a little faster than we shall have to do in the ordinary course..."
......Allen's own description is similar but less colourful. He did mention that two cast iron rail chairs in the curves had fractured...
LMS Vice President Sir Ernest Lemon said, at the press lunch:
"Of course, gentlemen, you will realise that we shan't need to do this kind of thing on every trip of the "Coronation Scot"; we were coming in a little faster than we shall have to do in the ordinary course..."
It always amazes me that the weight of PRR S1 without the tender was 304 short tons, PRR T1 was 251 short tons while LMS The Coronation Class was only 121 short tons!
M636C To revert to the original request, here are a couple of references: Loco Profile 24 "Pennsylvania Duplexii" by Brian Reed Profile Publications Windsor UK, 1972. Brian Reed was a locomotive design engineer with the North British Llocomotive Company. "Rekord Lokomotiven" by Wilhelm Reuter, Motorbuch Verlag Stuttgart 1978 pp 303 to 315, chapter title "The Big Engine". Peter
To revert to the original request, here are a couple of references:
Loco Profile 24 "Pennsylvania Duplexii" by Brian Reed Profile Publications Windsor UK, 1972. Brian Reed was a locomotive design engineer with the North British Llocomotive Company.
"Rekord Lokomotiven" by Wilhelm Reuter, Motorbuch Verlag Stuttgart 1978 pp 303 to 315, chapter title "The Big Engine".
Peter
Thank you very much, Peter. Those are some publishment form 70s, I wonder if it is still possible for me to find them. I really want to read them, If our forum members own these publishment and willing to share with me, please kindly pm me! Thank you very much!!
(Edit: I found a copy on the web of Loco Profile 24, but I am not sure if full name of "Rekord Lokomotiven" by Wilhelm Reuter = "Rekord Lokomotiven - Die schnellesten der Schiene 1848-1950", I can found plenty of them on amazon but I can't read German......
OvermodMeanwhile, the original Baldwin design provided for the T1 'thought' that all the drivers in both engines should be equalized together, which required some cleverness to get past the cylinder block for the rear engine. Their solution was the long pivoted beam on the prototypes.
OvermodOne big advantage that came into postwar truck design was the use of 'silentbloc' rubber bushings at contact points and joints. The French in particular made heavy use of this (and I think it was instrumental in achieving some of the contemporary high speeds reported for the equipment as early as the Fifties).
OvermodWhat's the source for the streamlined-duplex 'cut' you provided? That looks like something a British enthusiast would provide for a C1a using an auxiliary and perhaps corridor tender instead of track pans; we made very little use of that kind of deep angle cab even with vestibule, and the NYC cabs that had vestibules (the Niagara and A2a Berk important examples) had them up near deck height. Is there a story associated with the picture, or more explanation of its origins?
I have more information regarding the 1937 test run of the Coronation Scot and its description mentioned by Overmod.
There are three separate descriptions of the entry to Crewe in Cecil J Allen's "British Pacific Locomotives" from Ian Allen in 1962. My first edition has the price "65 shillings" pencilled in the back. The 1937 run is covered on pages 137 to 139.
R.A.Riddles, later credited with the design of the BR Standard locomotives, was riding the locomotive.
Part of his description reads:
"Spectators from Crewe coming into view along the lineside; and the train still hurtling at 114 miles an hour. On went the brakes, off the regulator but on we sailed, flames streaming from the tortured brake blocks.... We were still doing 60 to 70 miles an hour when we spotted the platform signal. The crockery in the dining car crashed. Down we came to 52 mph through the curve, with the engine riding like the great lady she is. There wasn't a thing we could do but hold on and let her take it. And take it she did; past a sea of pallid faces on the platform we ground to a dead stand, safe and sound and still on the rails."
Allen's own description is similar but less colourful. He did mention that two cast iron rail chairs in the curves had fractured...
Miningman Well thank you for that erikem. Wow that's some kind of twisted up thinking on the government's part.
Well thank you for that erikem. Wow that's some kind of twisted up thinking on the government's part.
... could you specific the detail of the ghastly unloading problem created by the long equalizing beam between the engines? I tired to search “steam engine unloading problem” on the web but it seems I found the wrong thing. I know the equalizing beam between the 2nd set of and the 3rd set of driver was removed from the production batch, but I don’t know about how a booster plus the equalizing beam affected the performance of 6111.
The two are really separate issues; I only mentioned them together in the context of problems affecting slipping in the evolution of the T1 design.
Remember that the T1 started with a somewhat ridiculously high FA, and was subsequently dialed even higher by the equalization changes; all this while the N&W J stayed ridiculously low. In other words PRR and Baldwin recognized there would be a price for short-wheelbase duplexing, and expected that the increase in nominal wheel load on driver groups would address it -- the physics did not match their expectations, and one of the things the T1 Trust modeling will find out is the extent of that.
The purpose of a booster on a locomotive of this kind can be thought of as providing an 'additional coupled axle' that at low speed can use the boiler-generated steam efficiently where the main engine(s) can't. They convert a Hudson briefly into a Mountain where starting a relatively long, heavy train is concerned, but when disengaged have no real effect on high-speed running (there is additional mass in the trailing truck, and some addition of unsprung mass on the rear trailing axle, but no unbalanced force in any plane from rotation, as there is with 'auxiliary engines' with rods).
Unsurprisingly, the NYC espoused the things, and perhaps also unsurprisingly PRR found reasons not to support anything the 'green team' was connected with. But as Staufer noted, by the time the Niagara design came to fruition there was no booster, and he noted famously that it was needed 'about as much as a Christmas tree sticking out of the stack' as far as 'starting any load it could pull' was concerned.
The issue at hand is different: whether the additional smooth and gear-enhanced traction provided back at a trailing truck would solve or at least ameliorate the low-speed slipping issues with four-coupled duplexes starting a train over typical yard trackage, or accelerating with short stroke to the 35mph or so where the T1's began to produce real acceleration. This would seem an ideal use even for something as simple as a Franklin E-2, but there's also a degree of 'where's my big savings?' both in first cost and maintenance if the booster only provides "equivalent" slip performance to a comparable 4-8-4. (And if there were problems getting PRR to use front-end throttles and poppet gear effectively, imagine the fun with warming up, engaging, and disengaging boosters with no cutoff adjustment...)
Meanwhile, the original Baldwin design provided for the T1 'thought' that all the drivers in both engines should be equalized together, which required some cleverness to get past the cylinder block for the rear engine. Their solution was the long pivoted beam on the prototypes. One effect of this was pronounced unloading of the forward engine under any particular load. Analysis of the suspension revealed that (no particular surprise) it was better to divide the suspension in the middle of the 'driver wheelbase' and tie off the equalization with helical springs and snubbing (which is choosing the spring rates so the various resonance frequencies are highly out of phase and the system as a whole tends to self-damp - this was a design principle on the GG1s but was later removed). By 1947 all this had been repeatedly refined (there are many noted drawing revisions on the equalization by then!) and things had been perfected about as far as they could be without actual damping via shock absorption.
One big advantage that came into postwar truck design was the use of 'silentbloc' rubber bushings at contact points and joints. The French in particular made heavy use of this (and I think it was instrumental in achieving some of the contemporary high speeds reported for the equipment as early as the Fifties). If you look at the two truck designs you provide, note the radius rods and shock absorbers required especially for outside-swing-hanger designs; I believe John White has a section on proper postwar design in The American Passenger Car (vol.2). More modern designs have much more emphasis on low unsprung mass and controlled degrees of freedom, but still require controlled damping of shocks and other running forces.
What's the source for the streamlined-duplex 'cut' you provided? That looks like something a British enthusiast would provide for a C1a using an auxiliary and perhaps corridor tender instead of track pans; we made very little use of that kind of deep angle cab even with vestibule, and the NYC cabs that had vestibules (the Niagara and A2a Berk important examples) had them up near deck height. Is there a story associated with the picture, or more explanation of its origins? By the way, if one of the unofficial goal to develop T1 was to outperform Diesel like the NYC Niagara 4-8-4 which successfully achieved, using a booster would at least increase the average annual maintained cost and average annual fuel cost as well.[/quote]
M636C but post war trains had coil secondary springs with some form of damping added.
but post war trains had coil secondary springs with some form of damping added.
Post war train truck in US and UK, Top: Commonwealth bogie (UK), Bottom: GSC 41-N-11 Passenger Truck (US)
M636C It is generally agreed that the PRR S1 and UPRR "Big Boy" are generally the same sizes overall, despite the UP locomotive having twice as many coupled axles.
It is generally agreed that the PRR S1 and UPRR "Big Boy" are generally the same sizes overall, despite the UP locomotive having twice as many coupled axles.
If that was the best a government can do to a company which contributed so much to win the war, that was really messed up.By the way, I wish people won't forget that she helped to win the war too:
Overmod The spec for the T1 was dialed back to 880 tons at 100mph, a far more reasonable number for a locomotive with four-coupled engines especially in light of the lack of boosters for starting (you will remember that one of the prototype T1s was built with a booster, but had it removed in spite of the ghastly unloading problem created by the long equalizing beam between the engines, which was thankfully purged from the production suspension).
I didn’t know that the booster was removed from 6111, could you specify the detail of the ghastly unloading problem created by the long equalizing beam between the engines? I tried to search “steam engine unloading problem” on the web but it seems I found the wrong thing. I know the equalizing beam between the 2nd set of and the 3rd set of the driver was removed from the production batch, but I don’t know about how a booster plus the equalizing beam affected the performance of 6111. By the way, if one of the unofficial goals to develop T1 was to outperform Diesel like the NYC Niagara 4-8-4 which successfully achieved, using a booster would at least increase the average annual maintained cost and average annual fuel cost as well.
Miningman Interesting thread with many branch lines! If you recieved a whopping 17.6% hourly pay increase on top of a banner year of hours worked that even beat your last extremely profitable banner year and revenues exceeded expense, but you lost all the money and dipped into last years, then I can only conclude you went to the Casino ... a lot! It has been my understanding that Pennsy had a sort of military structure, no one at each lower level would dream of questioning those at the next level. I think this makes it easier for secrets and info withheld level to level.
Interesting thread with many branch lines!
If you recieved a whopping 17.6% hourly pay increase on top of a banner year of hours worked that even beat your last extremely profitable banner year and revenues exceeded expense, but you lost all the money and dipped into last years, then I can only conclude you went to the Casino ... a lot!
It has been my understanding that Pennsy had a sort of military structure, no one at each lower level would dream of questioning those at the next level. I think this makes it easier for secrets and info withheld level to level.
I bet 70 years ago when the concept of transparency and Media's supervision were not a daily thing, it was a completely different world compared to nowadays. (recommended thread: Jim Crow laws & railroads ). The military structure thing you mentioned in Pennsy makes it more difficult to find the truth today. If the Head of PRR (or other Class I railroads) did cheating or other shady things, I believe it is a mission impossible to reveal the truth without professional investigation, but many people involved had already passed away, not many railway enthusiasts have that amount of resource and time to find the truth. But I think it is a good start to at least raising the question.
Something to add about PRR's financial status in 1946...
IIRC, Paul North posted some PRR ad's from the late WW2 time frame about having to defer maintenance on their track to to prioritizing wartime traffic over maintenance. At the same time the federal government forced the PRR to declare the "savings" from not maintaining their track and then taxing that as income, which was then subject to the high wartime tax rates.
It is generally agreed that the PRR S1 and UPRR "Big Boy" are generally the same size overall, despite the UP locomotive having twice as many coupled axles.
Looking at the boiler barrel as something to base a comparison upon, the dimensions were:
S1 100" diameter by 21' 11" long
4000 106" diameter by 22' long
So unsurprisingly, the 4000 has a bigger boiler, but not significantly longer.
I'll have to think about the fireboxes since the arrangements are so different...
Interesting! I guess Gresley Bogie and PRR 2D P5 truck both doesn’t have shock absorber, am I right?
As I said earlier, both these designs had full elliptical leaf springs for the secondary suspension. These are the sort of leaf springs seen on the British LMS three axle bogie above the axleboxes, but combined as an inverted set pivoted to an upright set at each end of the leaves.
A feature of these springs is that the leaves move relative to eachother as the spring compresses or expands and this provides a built in damping that avoids oscillation.
At the time these trucks were designed, automotive style shock absorbers were not generally available, and automotive shock absorbers of suitable capacity only arrived in the 1950s.
If you look at USA streamliners, most prewar trains had full elliptical secondary springing, but post war trains had coil secondary springs with some form of damping added.
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