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Ancient PRR R1 Model

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  • Member since
    January 2002
  • 4,612 posts
Posted by M636C on Saturday, August 12, 2023 7:19 PM

One interesting feature of the PRR using the same classification for steam and electric locomotives was the allocation of numbers for the electric locomotives.

Whoever allocated R1 and GG1 for the electric locomotives didn't expect any steam 4-8-4 or 4-6-6-4 types to enter service any time soon.

It seems possible that the PRR might have ended up with Challengers (GG5 ?) during WWII had the C&O 2-10-4 design not have been available...

However, the class P5 suggests somebody thought that a P1 Hudson was at least a possibility...

Peter

  • Member since
    September 2003
  • 21,320 posts
Posted by Overmod on Sunday, August 13, 2023 10:34 AM

M636C
Whoever allocated R1 and GG1 for the electric locomotives didn't expect any steam 4-8-4 or 4-6-6-4 types to enter service any time soon.

Material at the Hagley indicated that the 'revised' direct-drive steam turbine derived from the S2 6-8-6, which would have had the Westinghouse planetary transmission and been light enough for 4-wheel leading and trailing trucks (although this was amusingly fudged in the Westinghouse catalog in 1948!) would be assigned class R2.  Part of the discussion (by Cover IIRC) about the results of the N&W J testing was that any use of the design would involve 'higher wheels' for PRR passenger service -- it appears many people think this would have been 80", and that would be supported in a way by New York Central going directly from 75" to 79" on the Niagaras (and avoiding any further development on the C1a), but it could easily have been the 77" used on the Q1 as the "improved version of a M1a".  He doesn't describe a prospective class, and by that point PRR was firmly in the grip of divided-drive mania...
It seems possible that the PRR might have ended up with Challengers (GG5 ?) during WWII had the C&O 2-10-4 design not have been available...
No.  If PRR had decided on an articulated engine, it would have been the superior N&W 2-6-6-4 that would have been the starting point, or else the "equally-available-through-the-WPB" 2-6-6-6 Allegheny.  (Not only did PRR control N&W at the time, but its 50mph freight speed limit could be easily accommodated by the N&W engine's evolved two-wheel pilot truck.)  Challengers were just awful in the arrangement of their combustion spaces relative to an engine with a proper deep firebox (like an Allegheny or a Q2) -- where you needed the ability of a pin-guided lead truck to make a sort of "4-8-4-and-a-half' in minimum length they had a sort of appeal, but they were anaemic in almost any other respect compared to the equivalent engines fed by a deep-firebox boiler with all the main rods equal length.

However, the class P5 suggests somebody thought that a P1 Hudson was at least a possibility...

Someone go back and look at the records, but I suspect there were already classes P1-P4 already assigned historically.  This would be the same for L-class engines, with L1-L4 probably assigned to steam Mikados, L5 even with 'divided drive' the next slot, and L6 having individual drive on the four driver axles.

Note that the PRR was funny right to the end about high-speed six-coupled power.  They liked their Atlantics better for true high-speed running, and there is more than a little of that in the development of the divided-drive passenger engines (which were supposed to need no more than four driver axles to do the work of doubleheaded K4s).  The likely reason the P-motors were 2-C-2 was to make them bidirectional, and that consideration almost certainly wouldn't have applied to steam power.  (PRR was well aware of the bidirectional 'tank engines' on the DR in the Thirties, and while certainly planning for a "Hiawatha-equivalent" 4-4-2 in the stillborn E8 class, there appears to be no effort toward either a bidirectional high-speed engine or a six-drivered F7-style engine -- they went quickly to the double-Atlantic...)

  • Member since
    May 2019
  • 1,314 posts
Posted by BEAUSABRE on Sunday, August 13, 2023 6:22 PM

According to "Black Gold, Black Diamonds" Page 112-114, the PRR considered the WM Class M-2 4-6-6-4's, the SP's AC-9 2-8-8-4's, the DM&IR's 2-8-8-4 and the UP's Big Boys. But decided "No", probably because they were articulteds. The PRR also considered the 2-6-6-6, but eliminated it from the competition early and decided not to test it. As for the Class A "It had two strikes against it 1) It was an articulated, a breed the railroasd had little interest in, and 2) It was a high speed runner illl suited to lugging on the hilly mainline east of Pittsburgh." and after testing "The A could move freight fast, but seemed to have excessive apetite for coal and water. Also, it's ability to haul freight at speed was negated by the railroad's fifty mile per hour speed limit for freights". So, the PRR was not impressed by the Class A and would probably have chosen another articulated if they went that route. The C&O's T-1 was "A locomotive in the Pennsy mould, huge and powerful...and it haul a train almost as fast as an A. A T-1 was economical to operate and ideal fot its needs"

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