Why No Pennsylvania 4-8-2s In Passenger Service

Classic Trains General Discussion
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Why did Pennsylvania Railroad 4-8-2s pulled only freight trains and not dual service, passenger and freight. Why no PR 4-8-2s on passenger trains.

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I suppose, since steam was custom built for specific applications, the PRR built their 4-8-2’s for freight service. My casual observation of Eastern carriers was that most passenger engines were built with 80 inch diameter drivers. The larger the drivers the easier it was for the engine to sustain high speeds.

Engines with smaller driver found it easier to move increasing amounts of tonnage.

Observably the PRR passenger engine philosophy morphed from the K4 to the T1

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Hello,
the Pennsy mountains were originally built to be dual service engines. According to “Pennsy Power”, by Alvin Staufer, after the electrification east of Harrisburg was completed in the 1930’s, many K-4 engines were displaced. these K-4’s took over the passenger assignments handled by the M-1’s.So, they got bumped to freight service exclusively.
The M-1’s handled some passenger work in the 1930’s. There are shots of M-1’s in passenger service on Sunday River’s “Steam on Horseshoe Curve, part 1”. Black and white footage from the 1930’s.
Paul

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The surviving documentation in the Hagley indicates that passenger locomotive design, all the way through the T1 design and the analysis of the 610 J high-speed testing, had a fixation on ‘high wheel’ engines rather than lower augment and reduction of reciprocating mass, etc. You see this perhaps most vividly in the design of the Q1, which was explicitly designed as the 5/4 larger ‘replacement’ for the M1 and M1a as a dual=service locomotive – not only did this have divided drive, but 77" drivers – sorta like the pre-Eksergian formula for diameter speed.

The New York Central certainly got adequate passenger speed out of locomotives with 72" drivers, but interestingly thought their “5/4s replacement for Mountains” ought to have only slightly higher drivers, at 75". It was soon understood and agreed that a full 79" was worthwhile for high speed, and no production Niagaras were built with 75" or downsized after the Dieseliner era as they could easily have been.

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Looking at the PRR employee timetables at

http://prr.railfan.net/documents/EmployeeTimetables.html

we see some allow the 4-8-2s 75 mph and some just 60. I haven’t checked to see if all the later timetables have the lower limit.

(They don’t – NY Div tmetables 1951-52 say 80 mph for class M.)

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wow that makes alot of sense

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The interesting thing about 60mph is that it would have been a ‘passenger’ limit; PRR had the 50mph speed limit for freight firmly established in this period.

Could you be misreading 80mph as 60mph? The New York Division forward limit for M1/Mia in 1946 was 40mph light engine, 75 with train, but by 1952 the ‘with train’ rating had been raised to 80mph. Strangely, on the Middle Division in 1952, the light speed was 50mph, but the ‘with train’ speed was only 70mph.

Perhaps listing the exact ETTs and pages in which the slower ratings appear might be helpful, since there are so many of them to go through… not that I’m complaining!

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I suspect the reason light engines had lower allowed speeds than when the engines were operating with trains was in the braking. The tires on the drivers of steam engine were ‘shrink fit’ to the driving wheels. When braking, brake shoes apply to the wheel rims of the drivers and other wheels - brakes applying against the drivers put heat into the tires - if the tires would get ‘too hot’ they would expand and be able to come off the wheel.

BIG PROBLEMS.

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The issue I was wondering about was that the light-engine ‘allowed speed’ was 10mph faster on the Middle Division, with its tight curves, than on the high-speed electrified New York Division.

The concern about braking is correct. When ATSF 3751 was restored, it had to be tested with what I recall was a set of FuelFoiler skeleton-underframe flats, to increase the number of safely-brakable axles. There is also the problem of flatting the expensive driver tires if the brakes are misproportioned or the independent is not properly bailed off…

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“Could you be misreading 80mph as 60mph?”

As it happens, I looked at the 1949 St Louis Div, which does show 60 max for class M. But I see now M was allowed 80 in the 1951-52 NY Div. (Earlier, when the limit for M’s was 75, that was the limit for all passenger.)

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