NYC 2-8-4

[Overmod]

You could start by noting how NYC designed their 5550 (the S2a) not to take advantage of the type A gear for high speed, as PRR seems to have done on the T1s, but for much more efficient use of fuel and expensively-treated water at ~85mph sustained.

(And found no particularly useful gains from that, even disregarding the relatively high cost of the patent gear, culminating in a lamely early scrapping over a half-decade earlier than the piston-valve Niagaras.)

This leaves open whether the C1a, which was essentially a piston-valve T1 chassis under a Niagara boiler, would have succeeded better or longer than the T1s did.  The C1a shared the same extreme short stroke (and added risk of stalling) but with the only substantial grade being West Albany hill with a regular pusher present...

The elephant-in-the-room problem, of course, being the emphasis on Dieseliners for any train fast enough to make actual use of a 110mph+ locomotive, a locomotive with limited low-speed and starting potential for fast freight.

The T1a was kept as a 300psi engine even as it got piston valves.  I don't remember if PRR had to pay through the nose to replace cracking alloy boilers, but it does not seem that they ever reduced operating pressure even when sleeving cylinders to address perceived slipping issues.  (Even though there were 'known' effective starting techniques involving sliding pressure and' probably, substantial pressure cycling at starting from intermediate station stops.)

Something Polaritz does not go into detail about, but NYCSHS might have documentation for, was whether the boiler was built 'light' to take advantage of 230# pressure... and the years in corrosive storage conditions caused boiler damage like that observed in stored Q2s (Trains reporting in the early '70s that their boiler plate could be nearly eaten through in just a couple of years) and that was a reason Bellefontaine shops had such trouble putting them back in commission.

[Backshop]

I agree.  If a locomotive is doing the job it was designed for, no reason to stess it by making it more powerful.

PS--Is there a correlation there in the Niagara vs the T1?

[Overmod]

There is a vast and significant difference between the Lima A1 type and the A2as, even given the same driver diameter.  About a quarter century of design expertise.

I still find it highly notable that no Berkshire anywhere was built to "modern" high pressure, even though engines for KCS with but one more driving axle were built for 310psi.  I think this is very good evidence for the thread we had a couple of months ago about lower practical boiler pressures and observed cost-effective service life.

Niagaras were built for 290, but were quickly reduced to 275.  Yet were still nobody's idea of incompetent fast passenger power...

[Backshop]

The ones owned by the Boston & Albany, the first ones built, were effectively NYC locomotives.

[03 1008]

The article "The unwanted Berkshires" by Jack Polaritz was in Classic Trains Spring 2004, p. 32 ff..

[Overmod]

We've had threads on the A2a (A-2-A on P&LE).  The definitive work on them is by Polaritz (I keep misspelling his name!) and is worth owning.

https://www.amazon.com/stores/Jack-Polaritz/author/B001K93L88?ref=ap_rdr&isDramIntegrated=true&shoppingPortalEnabled=true

These were an interesting late design by Paul Kiefer, and 'reading between the lines' they were sorta forced on P&LE (which was extensively dieselizing 'for cause' at the time) to get Kiefer's design built.  There was a Classic Trains article about 20 years ago that did not think much of their design (e.g. 63" spoked drivers) and there were some fearsome reverse moves because the engines were too long to turn effectively on part of the route...

However, some of the engines were sent to the Indianapolis region where they did reasonably well... there is a video of one running quite freely at good speed.  The problem was that they had been laid up in the Pittsburgh area without careful storage, and had corroded badly by the time they were wanted; I suspect they nay have had the same metallurgical woes as the original Niagara boilers did.  Of course by 1954 "the fix was in" with any NYC modern steam.

[Fr.Al]

I don't know if there has been any discussion about these locomotives. I didn't know of their existence until relatively recently. I know they weren't built for the NYC originally, but rather for it's subsidiary Pittsburgh and Lake Erie. I understand they were the last steam locomotives built by Alco in 1948. I know the L&N acquired new Berkshires in 1949. I would be interested in finding out where and when these engines worked on the NYC. Obviously their newest steam locomotives.