I just saw a question in another online location that made me wonder. To my knowledge the Pennsy did not field a conventional 4-8-4 type steam locomotive. Can anyone tell me what the reason was for that?
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My guess would be they already had enough other engines! 😀
Mark in Oregon
They must have felt their J1 2-10-4's had plenty of power for what they needed. They had what they called an 'expanded' 4-8-4 with their 4-4-4-4 T1 locomotives. The M series 4-8-2 had plenty of freight power, and sometimes used there in passenger service also.
Pennsylvania's duplex drive 4-4-4-4's were essentially mid-1940's "state of the art" 4-8-4's. Why so late to the 4-8-4 type? Pennsylvania's motive power energies were invested in electrification projects in the 1930's, at the height of the 4-8-4's popularity. They got to the party late.
(Pennsy), heavy, I1 decapod would also figure into the conversation. ?? More decapods than any other configuration?? IMO. Middle shelf, Sunset Thirdrail decapod. Bottom shelf is a Weaver M1a mountain.
@Mike CT posted:(Pennsy), heavy, I1 decapod would also figure into the conversation. ?? More decapods than any other configuration?? IMO. Middle shelf, Sunset Thirdrail decapod. Bottom shelf is a Weaver M1a mountain.
That CP 4-6-4 reminds me that PRR was generally light in the Hudson department* as well. One wonders how they would have referred to 'em; certainly not Hudsons... ;-)
https://en.wikipedia.org/wiki/...ssification#P:_4-6-4
Mitch
*At least in the steam section of the roster. The P5 electrics are, of course, legendary.
Since the 4-8-4 was so successful on other roads, it makes me think that the PRR must have had a specific reason no to employ the design. It may not have even been technical. But when you have 4-8-2, 2-10-0 and even 4-4-4-4 styles in play, it seems odd not to have this style (edited).
No Hudson either. I recall reading something to the effect that Pennsy didn't go for the extra axle on the trailing truck because they didn't think it was needed. The Mountain and the Pacific did their jobs just fine so why go to the extravagance of an extra axle.
@Chuck Sartor posted:They must have felt their J1 2-10-4's had plenty of power for what they needed.
Remember, the J1's were a C&O design...
Rusty
@jhz563 posted:Since the 4-8-4 was so successful on other roads, it makes me think that the PRR must have had a specific reason no to employ the design. It may not have even been technical. But when you have 4-8-2, 2-10-0 and even 4-4-4-4 styles in play, it seems odd not to see a Hudson type.
It all boils down to what is needed for the railroad.
ACL, FEC, UP, NP, WP, SP, MP, C&NW and CRI&P didn't have Hudsons either. Nor did the CB&Q's subsidiaries C&S and FW&D even though the "Q" had them.
Rusty
The progression of PRR Steam essentially came to a halt after the M1 because of electrification.
Two reasons behind this:
1. When the PRR started the electrification of the NYC to Phila. main in the late 20s, they displaced their passenger steam locomotives (mostly K4s) from these lines. This surplus of mainline locomotives on the rest of the system diminished the need for new steam locomotives. More and more steam was displaced as the PRR spread electrification from Phila. to D.C. and later extended from Paoli to Harrisburg. There were so many surplus steam engines that they could doublehead on heavy trains (and the PRR was a big fan of doubleheading to their own detriment). There was essentially no need for new locomotives.
2. Electrification became the big focus for the PRR. In between a period of about 10 years from ~1924-1934, they designed and tested 7 classes of mainline electric locomotives (DD2, O1, P5, GG1, R1, L5, L6)***. Research money was essentially being redirected away from steam, and the PRR liked to design in house so it would be unlikely that they would buy a standard design from Baldwin or Lima.
***As a side note, the O1 (4-4-4) was designed to be the electric equivalent of the E6 while the P5 (4-6-4) was designed to be the equivalent of the K4... performance of the locomotives was not as good as the PRR desired on longer trains therefore the O1 was mostly used on shorter (non priority) trains. The subpar performance of the P5 sent the PRR back to the drawing board (leading to the GG1). The P5 was re-geared for freight service once the GG1s were designed.
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By the late 30s when the PRR realized that the aging fleet of K4s needed replacement, steam design had progressed past 4 sets of drive wheels being connected by a single side rod. The reciprocating mass of the side-rod would pound the track. The PRR instead chose to go with an articulated locomotives due to this reason (less centralized reciprocating mass), along with the fact that duplexes could use smaller cylinders, and required lower piston axial force than a conventional locomotive.
Therefore, instead of going with a 4-8-4, they went with a 4-4-4-4 (two sets of 4 drive wheels instead of one set of 8).
During the war, the government did not allow for experimental locomotive design, therefore the J1s were built from the C&O 2-10-4 design as they were needed heavier locomotives for long slow hauls (therefore no 4-8-4 freight engines for the PRR)
The S2 turbine (1944) was supposed to be a 4-8-4 design, however wartime restrictions forced the PRR to use heavier steel alloys in the locomotive (lighter alloys of steel were needed for the war effort). Therefore 6 wheel leading and trailing trucks were used.
By the late 40s, dieselization crept in and there was no need for more new steam locomotives.
@Rusty Traque posted:It all boils down to what is needed for the railroad.
ACL, FEC, UP, NP, WP, SP, MP, C&NW and CRI&P didn't have Hudsons either. Nor did the CB&Q's subsidiaries C&S and FW&D even though the "Q" had them.
Rusty
You might have missed the CNW E4 Hudson. They pulled the Challenger passenger train.
@third rail posted:You might have missed the CNW E4 Hudson. They pulled the Challenger passenger train.
You're correct. Missed that one.
Rusty
Remember that the PRR Mechanical Department was seriously afflicted with that dreaded "Not Invented Here" syndrome. Even after testing an N&W J Class 4-8-4, they simply could not, and would not, believe the J's spectacular performance.
To follow up on Hot Water's comment, the PRR Mechanical Department suffered from more than a touch of ego when it came to locomotive design. They were so heavily invested in trying to make the duplexes successful they initially ignored data showing the superiority of diesel power until 1947 and then ordered as many as they could find from every manufacturer as EMD couldn't provide the volume of locomotives they needed to replace what was by then a largely archaic fleet of steam locomotives.
Many suspect that if they had developed an R class steam locomotive, it would have had a long and successful career in the exact same way the duplexes didn't.
@jhz563 posted:Since the 4-8-4 was so successful on other roads, it makes me think that the PRR must have had a specific reason no to employ the design. It may not have even been technical. But when you have 4-8-2, 2-10-0 and even 4-4-4-4 styles in play, it seems odd not to have this style (edited).
That seems a bit backwards. When you have a variety of alternative designs already fulfilling the role a 4-8-4 would service, I don't see what the need for a 4-8-4 would have been.
Given Pennsy's commitment to electrification and the surplus of locomotives that generated, the decision not to go with Hudsons and Northerns makes some sense. The question though is why go with the experimental Duplexes in the 1940s rather than the proven super powered Northerns.
@SGP posted:That seems a bit backwards. When you have a variety of alternative designs already fulfilling the role a 4-8-4 would service, I don't see what the need for a 4-8-4 would have been.
Maybe a "modern" Super Power 4-8-4 would have been better/cheaper than double heading K4s Pacifics all the way to Chicago and back in the late 1930s thru the late 1940s.
I think it has been covered, but I think there are a few reasons why PRR did not get any steam 4-8-4s (they did have at least one electric 4-8-4, class R1)
First the Pennsy from early in the 20th century had a conservative design policy that indicated that simpler was more efficient and lower maintenance. This translated into fewer axles per loco - fewer bearings and less friction, less things to maintain. The prime example is the E6 4-4-2 that was the equivalent to many roads 4-6-2s. PRR had a very heavy duty mainline roadbed and track, and therefore could afford heavy axle loadings. This design policy carried over to 2 rail trailing trucks on PRR designed stuff. Remember the last K4s were built in 1928 which I think made them contempraries of NYC Hudsons The M1As were built with cast steel frames and variouis other "modern" improvements at the time.
Second the electrification used a lot of available capital and made a lot of steamers excess. An example is the many of the L1 mikados were put into storage because they were not needed and I think quite a few consolidations were sold off. The L1s were pulled out of storage and put back in service during WWII but many did not have stokers because they had not received them prior to storage. The M1/M1A classes could hold down the freight assignments on the Middle division and out west while the I1 decapods could handle the Pittsburgh division freight over the mountains in both directions. PRR also looked to electrify the mainline from Harrisburg to Pittsburgh over the mountains and did at least two and I think 3 justifcation and feasibility studies.
Third by the time they were considering more modern steam in the early 40s, they realized that the bigger locos were pounding the track and causing more maintenance and making high speed harder to obtain because of the needed counter balancing. Therefore they looked to the duplex idea (not articulated, rigid frame) to provide lighter mechanisms. Hence the T1 and others. The T1 could probably have been very successfull if it had been built a decade earlier. By the time it was built, diesel electric locos had become reliable and available and there was just no need to work the bugs out of the latest steamers.
I recall in the "Thoroughbreds" book about NYC Hudsons that one of the former employees they quoted said that NYC Hudsons and Penny K4 Pacifics were both perfect engines for what they were designed to do, to run on the track each railroad had between New York and Chicago - and that they wouldn't have worked as well if you'd swapped them. Each design was unique to what the railroad that built them needed.
As far as Northerns - which were primarily heavy passenger power for top-line trains - it seems like Pennsy had no qualms about double-heading K4s on long trains, where other roads bought larger engines so they only needed one. As noted, during the Great Depression, PRR put it's money into expanding electrification. By the time they started experimenting with 4-4-4-4 engines, the top passenger engines were diesels, like E-units...which Pennsy did buy.
