I really enjoyed the Classic Trains special on 4-8-4's. So much info I never knew about. Wonderful photos, including rarities of the small TP&W & T&NO classes - machines I'd never seen before.
However, I was most intrigued by the statement in the magazine that the Pennsy's M1 4-8-2's were of equivalent capability to the 4-8-4's of other railroads. I assume the author had in mind the up-rated M1b variant with increased boiler pressure of 275psi. How could this be possible? There must be more to it than just a bigger combustion chamber and higher calorific coal (not to mention the Kiesel exhaust nozzle)?
I ask not because I doubt the statement, but because I'm fascinated by its implication that the Pennsy's policy of researching, testing and improving their designs meant they could get 20-30% more power per sq.ft of grate than off-the-shelf designs of other railroads. Other than the factors mentioned above, what else did the Pennsy do to get such improvements?
PRR's original M1/M1a's had relative large boilers, even if the grate area was only 70 SF. If you compare the M1a to smaller 4-8-4's such as TP&W, NC&StL, NdM, and GTW, to mention a few, it's entirely possible the M1 could offer similar or greater performance capabilities because of its larger cylinders, similar BP, and larger boiler as reflected by direct and indirect heating surfaces and superheater size. The M1 was no slouch..
Would they have had boosters for hard starts, whereas few 4-8-4's had them if I recall. The drivers were smaller in some cases, with the same crank circumference...ergo, more rotational effort for the weight of the locomotived.
Crandell
PRR did not in general use boosters. The Chessie 2-10-4's had them but not the PRR
The answer is the weight of a Belpair firebox of equivalent capacity to a regular firebox and the distribution of the locomotive's weight. The J's were the only non-duplex PRR steam power to require four-wheel trailing trucks, and they did not have Belpair fireboxes, being a copy of the Chessie's. If the K5 had been built in quantity, it probably could have matched the Central's J1 4-6-4. But electrification and the Depression ended the need for new PRR passenger steam power, up to the wartime need for the T1.
Several years ago, while sifting through several boxes of drawings delivered to Steamtown by the widow of a PRR draftsman, I came upon what I assume was a "conceptual" sketch of an "R-2" 4-8-4 for the PRR. It featured a Belpaire firebox, the J-1 style cab and boiler, and pilot-mounted air pumps. Was it the draftsman's idle doodling, or had some Motive power Department official asked him to do this? I wish I'd had access to a copy machine!
It may have been a conceptual drawing for the original ideal of the S2 turnbine, it originally was to be a 4-8-4 but was changed when war time materials could not accomodate the weight, so it was then changed to the 6-8-6 configuration. The PRR did have an R class locomotive with a 4-8-4 arraingment, the R-1 electric the one and only such 4-8-4 locomotive on the PRR.
Usually assigned to haul the Lehigh Valley trains between Hunter Tower and Newark and Penn Station, New York, and Synnyside Yard. It had a body design similar to Rivits, the original GG1.
Dave is correct that PRR in general did not use boosters. However, all of the J1/J1a 2-10-4's, all Q2's, the Q1 and one of the T1's (6111) had them. PRR didn't think they were worthwhile for passenger engines, but incorporated them on their last freight locos.
The R1 was actually an alternate design to the GG1. The R1 was originally numbered 4800 and the first GG1 was 4899. Most enthusiasts are aware of the trials conducted at the Claymont test section which quantified the various superior qualities of the GG1.
It's entirely possible that Pennsy's M Class Mountains could outperform a 4-8-4 in some respects, especially in the ability to start a heavy train. The Mountain type had one less truck axle and that put correspondingly more weight on the drivers which improved tractive effort and they had a smaller driver than most Northerns which also improved pulling power at lower speeds. The Southern Pacific had a large class of MT class Mountains which they could compare with their G class Northerns and that's what they discovered, namely that the Mountain could start a train more easily than the Northern and perform just about as well out on the road.
Fron what I was told, the Pennsy J's lost t heir boosters. They were not maintained and were removed at the first overhaul. Possibly this applied just to a few, and my informant generalized?
I went through a lot of my PRR books and photos this AM, but I didn't find a picture of a PRR J1/J1a without a booster. Whether they were used or maintained, can't say, but the piping is there. Some may have had their boosters removed, I just haven't seen any evidence of it.
feltonhill I went through a lot of my PRR books and photos this AM, but I didn't find a picture of a PRR J1/J1a without a booster. Whether they were used or maintained, can't say, but the piping is there. Some may have had their boosters removed, I just haven't seen any evidence of it.
I looked at all of my PRR books and I tend to agree with your assessement. Even in 1956 on the coal trains out of Columbus to Sandusky, the piping for the booster is still on the J1's. They were maintained on the J1's I watched up until 1954 when they were replaced by diesels on the St. Louis main line. There might have been an exception in the very last days of 56 or 57, but in general, they were used and maintained.
CZ
Being from the UK, info about US railroads is a bit hard to come by. I see I've stumbled upon a group of people with a good knowledge of their PRR locomotives and related material etc. Should I have been surprised? After all, PRR is to you guys what the Great Western Railway is to us over here - i.e. having masses of fans and limitless available literature!!
So, as the M1's are one of my favourite steam loco designs, do any of you know of any books that exclusively cover this engine? I don't care if they be albums or more technically based. I would just like to learn and see more about them.
The only complete book I know of is: Pennsy M1, Classic Power #8, by Bert Pennypacker, ca 1990. It's been out of print for years, but you may have some luck at one of the internet used book sites. This should get you past some of the "international" problems.
There are several good articles that have been written:
1. The Standard Railroad's Standard (M1) by Richard Adams in Mainline Modeler magazine, Jan 1987
2. The Mighty M1's by Fred Westing in The Keystone, Vol 12 #2
3. The Mighty M1's Continued by Richard Adams in The Keystone, Vol 12 #3.
The Keystone is published by the PRR Technical and Historical Society and they sell back issues. See their website for availability and prices.
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