Jones1945
Pennsy could have built their own duplex and set the price of the new engine independently, that means Baldwin would have lost their largest client. If Pennsy really had such intention, once Pennsy obtained all the data of the S2 turbine, as well as the T1s, they would have ditched Baldwin afterward. How Baldwin would have had reacted to such a situation? the plot thickens...
To paraphrase the sense of the Easter service, 'thickens indeed'!
Baldwin was a principal player in the 'intellectual property' development of the duplex idea (perhaps overly so) -- this being one of the key post-Eksergian efforts to eliminate the evil effects of augment. How much the railroad world was pawing around in the half-dark is evidenced by the infamous R1 story; how clearly they got a good answer is not much later (in the 'refit kits' on, for example, the T&P 2-10-4s, the rebuilt 3751 class; the double rebuilding of the Hs into world-class glory matched (imho) only by the Niagaras). But in the world of the Q1, anything larger than -- say -- the M1a was going to be hopeless at dual-service speed, and so...
There's an old riddle about 'what's a camel?' The answer to which is 'a horse designed by a committee'. Here's PRR designing a 5/4 M1 but deciding to get more and more carried away with the fun, evidently forgetting Leonor Loree's lesson about practical technology on the way.
Part of the 'key' here is to note why the driver size was ramped up all the way to 77" instead of using disc centers and better balancing at 72". -- it's highly likely lower water rate a la Golsdorf was not part of that design decision, considering the priorities in the Q2 and V1 designs. Instead, as in the B&O locomotive (and I suspect the putative ATSF 6-4-4-4) you have conventional drive on normal wheels which now can have smaller balance weights and overbalance consequences.
PRR was, according to some of the notes at the Hagley, proud of the way it handled the steam'pipe and snifting valve arrangements at the rear of the Q1 to avoid the kinds of problems B&O had on their locomotive. If you look at it from pure engineering, they did a pretty good job. Just that nobody told the steam, and the dirt, and the things in casual collision with items located near the limits of the loading gage, about how to respect products of superior intellect ... as it were.
End result is interesting precisely because the design didn't try to do what the Q2 did, produce very high horsepower at elevated speed, so you wound up with a super locomotive hobbled by just the wrong constraints to realize the promise of the 'good bits'. Most of the issues of backpedaling drive were not particularly difficult to address (ahem, cough, cough, cab-forwards?) probably including the issue of crap rammed into the multiple-bearing crosshead surfaces, so you may be looking at T1-failure-duplicitous levels of railfan-led-by-the-nose mythology there. On the other hand, limiting the locomotive to M&E as its prospective 'dual service' (in a world where PRR freight never topped 50mph) can be seen without particular reference to accurate hindsight as a relative waste of time and money.
Nobody seems to have thought very carefully that a locomotive that required the same cylinder care and maintenance as two M1s had better be capable of doing more things better than two M1s as possible (particularly if it cost more than three M1s to build, but I digress). We see the same issue repeated for the Q2s as soon as no one needed 150-car trains pulled at meteoric speed over wartime-maintenance track: in a normal PRR world, the J1a (no slouch of a design itself, particularly with the upsized driver diameter) did about everything a Q2 could do on any particular practical train but with Ferrari-level maintenance for Ferrari performance the job no longer called for.
MEANWHILE ... back to the Baldwin story.
You will remember how the order for the T1s was split, half to Baldwin and half to Altoona, with the expensive valve-gear and technological bits outsourced (so Baldwin had no technological 'lock' on the market as they would have, via their controlling Westinghouse connection, on steam turbines). Behind the scenes, here comes the future! as Steins et al. duke it out with Loewy over the 'triplex' plan and then develop the magic solution that would replace reciprocating steam with a three-box configuration that didn't involve Baldwin Locomotive Works. (Although it did involve Westinghouse, about which more anon).
Baldwin, seeing its own future more than a little closely aligned with that of Steins et al., decides to implement its own 'hush-hush' design effort to end-run around the Steins patents ... the result of which comedy was (as no one I suspect will be surprised to learn) the C&O M-1 turbines. (In case you were wondering why there were three, and so little testing was done to debug the first one...) This essentially threw down the gauntlet to PRR Motive Power in a way that makes it potentially easier to see why no further direct-turbine work was undertaken at that critical time that turbine steam power was the wave of the future... and the compound-expansion answer to the whole double-maintenance problem of the duplexes at a stroke.
In my opinion, had there been no turbines we might have seen some attempt to de-sow's-ear the Q1, probably involving a switch to smaller drivers and perhaps some rebushing of the cylinders to adjust the cyclic water rate upward to suit (and perhaps some application of RC poppet gear in a reverse T1a change to three-valve Franklin type C as on ATSF 3752, but I doubt it). At this point I am tempted to speculate a bit and note 'what if we put a welded boiler and better firebox on the chassis, and geared in a couple of smaller V1-style turbines with the full-proportional version of the Q2 slip control' which still wouldn't have solved the lethal water-rate problem but would give us a highly interesting testbed... just don't expect Baldwin to build the pieces.
I suspect much of the correspondence over the design options here would make interesting reading