kgbw49Leaving Chicago Union Station... Leaving Chicago... Passing Van Wert, OH on the advertised... Waiting for the highball... Pittsburgh engine terminal... A little wear and tear but ready to chew up the miles... Rockville Bridge... Clean stack through Harrisburg, PA... Making time through Pittsburgh, PA... Fresh off the showroom floor...
Leaving Chicago...
Passing Van Wert, OH on the advertised...
Waiting for the highball...
Pittsburgh engine terminal...
A little wear and tear but ready to chew up the miles...
Rockville Bridge...
Clean stack through Harrisburg, PA...
Making time through Pittsburgh, PA...
Fresh off the showroom floor...
Some engines have the Keystone mounted on the housing just above the coupler. Others have some kind of light mounted there. What is the signifigance of the light?
Never too old to have a happy childhood!
I would guess that the locomotives with the low-mounted Keystone would be 6110 and 6111, which could be described as pre-production models.
CSSHEGEWISCHI would guess that the locomotives with the low-mounted Keystone would be 6110 and 6111, which could be described as pre-production models.
Out of the 10 pictures that were quoted in my prior post, 6 had keystones and 4 had lights. Can't read engine numbers in the 10 pictures.
BaltACD, my take on the T1 Keystone number plate location is that it changed when the front end was modified.
It looks like even the production units had the low number plate when they had the "fancy" front end with the three small portholes on the sides and an overall more bulbous look, as exemplified by 5528 in the last photo (which appears to be taken right after it was released from the shop). In that configuration, access to the running boards looks to be via grab irons and some recessed steps.
But it looks like the front ends were modified at some point to give access to the running boards by the more traditional slanted ladders, at which point the Keystone was moved up to the prow just under the headlight. It seems like the ladders give better access to the running boards for maintenance crews and it looks like the redesign also removed skirting from the sides in front of the first set of pistons, which I am surmising might also make maintenance easier. The second last photo shows 5500 with the modified front end.
That is just my best guess. Perhaps there are some Pennsy steam experts out there who could shed more light?
There are two distinct front-end styles for the 'production' T1s. The first style is the one with the portholes, and the center low-mounted keystone. These were rebuilt very quickly to the 'later' version with the Timken Stoker-like housing with the 'auxiliary light' in the middle, and keystone up on the prow where it belongs.
By the way: I had thought the light oscillated, a bit like a poor man's Mars light. It does not - it's just an extra 'fog' light. (Found the detail drawings!)
A few more interesting T-1 photos...
PRR T-1 pulling what must be express box cars...
PRR T-1 5537 fresh out of the shop...
PRR T-1 6110 Builder's Photo...
PRR T-1 5501 view of the front end set up...
PRR T-1 6110 being tested at Altoona...
PRR T-1 Prototype testing clearances (Pittsbugh, perhaps?)...
PRR T-1 ready to depart unknown location next to station switcher...
PRR S-1 6-4-4-6 Duplex with 84 inch drivers and total engine and tender length of 140 feet, five feet longer than the Big Boy at 135 feet, racing a NYC J3a Hudson out of Chicago...
PRR T-1 5519 traditional wedge shot from the back end...
PRR T-1 5517 roster shot in Fort Wayne IN...
PRR T-1 6111 publicity shot with rods down on the front drivers...
PRR T-1 55?? getting coaled up...
kgbw49 -
Just love that photo of the S1 Duplex and streamline NYC Hudson 5519 heading east out of Chicago - MAGNIFICENT ANACRONISM! so perfectly illustrated!
The Hudson - Superlative machine near the end of its magnificent career with literally thousands and thousands of successful miles pulling revenue passenger trains at high speed and - THE MARQUE of successful passenger engines replete with roller bearing drive - combustion chamber - and gladiator warrior styling!
The Duplex - the largest high speed passenger engine of its type ever built - experimental - non standard - unusable for most purposes for which it was designed - a vision of the future! And - so very very very fast!
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The engineer of the Hudson must have felt totally outclassed in his already famous race horse - the engineer of the Duplex must have felt it was time to overthow the reigning speed queen - finally something faster than a Pacific!
The photo shows the real true size - not the height of the Hudson - and the never ending mystery of the duplex!
Both engines are moot - the end of a glorious age of what was and what could have been!
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Thanks for the great photo!
Doc
Great shot of the S1 racing the Hudson! I wonder who won the race that day?
One thing's for certain, the loser would have said "We weren't racing!"
A couple of informational items on the PRR S1...
S1 Builders Photo...
S1 at Fort Wayne IN...
S1 in service - the size of the people give scale to the enormous size of this locomotive...
S1 coaled up and ready for service...
I have often wondered how the Lionel people could ever have confused this
with this pudgy thing
when writing a children's story about the Torpedo, the fastest and most modern locomotive in the world. Seems pretty obvious to me that someone got mixed up looking at their historical pictures...
Of course, if the object is to sell Thomas/Skaneateles compatible toys, then you need a short tubby 'streamlined' thing. But honestly now, which one is the better torpedo?
RME,
Had a chance to visit NYC 3001 4-8-2 Mohawk in Elkhart, Indiana this holliday season. Specifically to examine the Valve Pilot Indicator speedometer that survives on this locomotive. This highly accurate speedometer was standard equipment on most of the Central steam locomotives of the World War II vintage. The speedometer of NYC 3001 reads out to 120 mph.
This would seem to challenge your post indicating that Pennsylvania Railroad would not have equipped the T1 Duplex 4-4-4-4 with a speedometer greater than 100 mph and the S1 Turbine 6-8-6 locomotive with a speedometer greater than 110 mph.
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Examination of PENNSY POWER by Alvin Staufer - page 220 indicates the styling of the T1 Duplex came in three forms - with a fourth modified type designated the T1a.
Type 1 Experimental 1942 T1 - These were locomotives 6110 and 6111 built experimentally by Baldwin Locomotive works in April 1942. 6111 being the only duplex which was equipped with a low speed booster engine. Styling was by Raymond Loewy. These engines were the brain child of famous Baldwin engineer Ralph P. Johnson who also published in 1942 his famous work on steam locomotive engineering THE STEAM LOCOMOTIVE.
Loewy's styling of these two engines was different than the engines that were to follow - they featured a chisel shaped front boiler cowling which came almost to a point - and then tapered far back to the frame location of the first cylinder crossheads. This early design further included a a large front deck appliance cowling with "port hole trim" and no running board ladders. A low mount keystone number board was featured on the lower cowl.
Type 2 Baldwin Production 1946 T1 - This design included a newer boiler front cowl design with a now "blunt prow" that tapered back the chisel shape only to the frame location of the first axle of the front truck. I believe this would have allowed the standard smoke box front course shape to be completly round at the location of the hidden inside boiler front.
This "type 2 production 1946 T1" design retained the same large front deck appliance cowling with its "port hole trim" of the "type 1 experimental 1942" engines.
Type 3 Altoona Production 1946 T1 - This featured the same "blunt prow" boiler front modifcations of the "Type 2 production 1946 T1" design, but now also included changes to a new "narrow lower appliance cowling" which then allowed running board ladders to equip the locomotive front ends - now sans the stylish "port hole trim" design.
The "low mount" keystone engine number board was then moved up to just below the headlight on the blunt boiler front cowling of the locomotive. Further changes included a reduction of the streamline side skirting attached to the locomotive side running boards.
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Type 4 Altoona T1a - These changes required a re-designation of the type T1 to T1a classification for only one locomotive T1 5547. The "type 4 changes" came about when certain locomotive maintaince problems lead to a rethinking some of the T1's initial features. Opportunity for these needed changes were first considered with the rebuilding of T1 engine 5500 which recieved "continuous contour rotary valve equipment" but remained a T1.
Changes also occured with the rebuilding of T1 engine 5547 which resulted in entirely removing all 4 of the high speed poppet valve gear systems - change significant enough to reclassify engine 5547 as T1a type. This extensive 5547 rebuild included the manufacture of completely new cylinder steamchests for all four cylinders and refitting with retro style - Walschaert valve gear setups - no small task.
The T1/T1a rebuild/re-thinking included other changes to all the following rebuilt engines - a new box style classification lights on each side of the boiler front - and the inclusion of a second alternate headlight systenm - also called a "fog light" - to be mounted on the lower appliance cowl - in place of the former "low mounted" keystone number boards. All engines eventually recieved this treatment.
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Staufer notes the following engine power numbers for the T1 Duplex 4-4-4-4 engines which is quite remarkable:
"To fulfill the contract with Baldwin Locomotive Works in the construction of the T1 expermental engines 6110-6111 only 2,980 horsepower was required. 6110 topped this by 38% producing 4100 indicated horsepower at 100 mph.
Compared to Pennsy M1a 4-8-2 design the T1 Duplex produced 46% more drawbar horsepower with but 11% more steam usage per hour.
Test plant data for the T1 Duplex are as follows,
Maximum drawbar horsepower - 6,110 hp
Maximum indicated horsepower - 6,552 hp
Test run at speed of 85.5
Cut off - 25%
Boiler Pressure - 295 psi
Steam chest pressure - 287 psi
Indicated horsepower was 4838 at 38 miles per hour, and was usually above 6000 horsepower at all speeds over 55 miles per hour.
The T1 Duplex out performed 4 unit 5,400 horsepower diesel engines on the property at all speeds above 26 miles per hour.
Engine 6110 made the first run from Harrisburg to Chicago with 14 coaches weighing 1000 tons. From Crestline, Ohio to Fort Wayne, Indiana ran 20 minutes ahead of schedule the run completed to Chicago an additional 13 minutes ahead of schedule - for a total of 33 minutes ahead of schedule. Speed was consistantly in neighborhood of 100 miles per hour.
With a heavier train of 16 cars T1 Duplex 6110 performed even better running the Fort Wayne, Indiana division speedway at an average speed of 102 mph for 69 continuous miles!"
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I think you might want to reconsider you opinion about the speed capacity of the Pennsy T1 Duplex 4-4-4-4 locomotive.
LIONEL - Also was the worlds best maker of TOY trains - good for running across the rug - under the dining room table - past the "chase lounge" - or alternately round round the X mas tree - a considerable engineering challenge in its own right - when done correctly! You must forgive a few historic in-accuracies to accomplish this!
Indeed the S1 Duplex 6-4-4-6 beauty was truely heroic and considering todays standards of overall size increases in equipment maybe a better choice for reproduction that another less stylish T1 Duplex 4-4-4-4.
Best of the New Year!
Well yes, it HAS been suggested that a replica of the S1 would be a lot more, well let's say "cool," tan a replica of the T1, but remember an S1 replica would have the same problem the original had. Not that it didn't perform well, it performed beautifully. The problem was it was too damn big!
Too big for any of Pennsy's turntables, it had to be turned on wyes, and even then it had to be handled with kid gloves or it would derail. And sometimes it derailed even with kid glove treatment. In a way, it was a locomotive equivalent of a boat built in the backyard that can't get out past the house and to the street.
Too bad, it was a good performer otherwise. Anyway, the size of it was the reason it was the only one built. Too bad it wasn't saved just the same.
I've always greatly preferred the styling of the S1 to the T1 and feel that cleaned up a bit it would have made for a sleek locomotive if applied to a more conventional 4-8-4 (which was probably more what the PRR needed anyway). Just peel back the side skirt to show more of those huge drivers, eliminate the strange fin just under the nose and clean up the pilot and you've got a very pretty locomotive.
Dr DEngine 6110 made the first run from Harrisburg to Chicago with 14 coaches weighing 1000 tons. From Crestline, Ohio to Fort Wayne, Indiana ran 20 minutes ahead of schedule the run completed to Chicago an additional 13 minutes ahead of schedule - for a total of 33 minutes ahead of schedule. Speed was consistantly in neighborhood of 100 miles per hour.
.
BigJim Dr D I am going to question this validity of that statement. Were there any scheduled timetable stops anywhere along the way between Crestline and Chicago? If so, the train could not leave a station, or pass any timetabled point, before the scheduled departure time. Therefore, the train could make up time being late into a station, but the only way that it could run early into Chicago was between Chicago and the last stop where it would have left that station on time.
Dr D
I am going to question this validity of that statement. Were there any scheduled timetable stops anywhere along the way between Crestline and Chicago? If so, the train could not leave a station, or pass any timetabled point, before the scheduled departure time. Therefore, the train could make up time being late into a station, but the only way that it could run early into Chicago was between Chicago and the last stop where it would have left that station on time.
Speculation - 14 coaches might equal the Trailblazer, the PRR's 'through' coach streamliner. Such streamliners discouraged 'local' pick up stops for passengers, relegating them to other local trains that specialized in picking up passengers at every tank town and milk stop. As such, it may have been authorized to operate in advance of it's scheduled times - especially since it was not operating over single track, timetable and train order territory from Harrisburg to Chicago.
Rode the Trailblazer westbound late June 1952. Diesel power after Harrisburg. No pickup stops west of Fort Wayne, only discharge, Arrived in Chicago 15 minutes ahead of schedule. Similarlly only pickup stops east of Harrisburg, no discharge. Comfortable, smooth ride. Only El Cap highlevel coaches better.
The point is, if the train was timetabled, it cannot leave a station before the time stated.
Dr DHad a chance to visit NYC 3001 4-8-2 Mohawk in Elkhart, Indiana this holiday season. Specifically to examine the Valve Pilot Indicator speedometer that survives on this locomotive. This highly accurate speedometer was standard equipment on most of the Central steam locomotives of the World War II vintage. The speedometer of NYC 3001 reads out to 120 mph. This would seem to challenge your post indicating that Pennsylvania Railroad would not have equipped the T1 Duplex 4-4-4-4 with a speedometer greater than 100 mph and the S1 Turbine 6-8-6 locomotive with a speedometer greater than 110 mph.
Except that we have no evidence of a speedometer design for the T1 that reads higher. (And it's highly unlikely that the S1 received a new, faster speedometer than it was given as a high-speed experimental locomotive...) [As a note - the S1 was the 6-4-4-6 duplex; the S2 was the turbine]
It would be interesting to see whether the T1a was fitted with Valve Pilot using a speed reference independent of the Jones-Motrola it was built with (the speed reference for the Valve Pilot's "computer" being taken from a different axle than the 'native' T1 system used), If the device as used on PRR actually had a dial display, it would be interesting to see if it read up to 120mph as 3001's does, or indeed if 120mph is a "standard" for some locomotives that integrate speed recording with Valve Pilot.
Frisco 1351 has a postwar installation of Valve Pilot but I don't recall it having a speedometer, just the 'needle matching' that would have been used at any part of operation. I will have to sneak up and check.
BigJimThe point is, if the train was timetabled, it cannot leave a station before the time stated.
If authorized by special instructions it can. There is more to a timetable than schedule times.
BigJimif the train was timetabled, it cannot leave a station before the time stated.
(That exception is in the 1947 PRR rulebook-- it's not in the 1925.)
In any case, if it doesn't pick up passengers they could run it extra if they wanted to run ahead of its schedule.
Great thread. Not much brings out the photos, superb comments and total fascination as the T1's do.
So mysterious, so imaginative, so fast and powerful and lost to us entirely before we could really understand it, grasp it, know it ..vanished like a dream...and the stories and lore keep coming. A future lost to us, never revealed.
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.
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?
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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.
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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!
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- Doc
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.
Nice work and summation Dr D. Handy little reference.
At least we had that glimpse and PRR tried. However... the FIX was in.
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?
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
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.
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.
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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.
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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.
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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
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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.
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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.
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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!
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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.
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