ALTHOUGH IT COULD BOAST a legendary fleet of en-
gines backed by the splendid Altoona Shops, as war loomed
the Pennsylvania was mostly out of step with steam locomo-
tive technology. Emblematic was a total lack of engines with a
four-wheel trailing truck, a fundamental component of mod-
ern power. Suddenly, PRR signaled big changes with its S1
6-4-4-6 duplex of 1939, an experimental high-speed passen-
ger engine, then continued duplex development with two T1
4-4-4-4s and a lone Q1 4-6-4-4 freighter in 1942.
PRR looks to
the future
Q2 6131 is at Chicago in 1948.
The 25 Q2s of 1945 had less
sheet metal trim above the
cylinders. Paul EilenbergerPennsylvania S2 6-8-6 turbine,
Q2 4-4-6-4 duplex
The S2 turbine strikes a grand pose near Harrisburg, Pa.,
in mid-1944, before addition of smoke deflectors.
PRR: A. F. SozioIn 1944, Pennsy solidified its commitment to the cutting
edge with two radical machines. The first — the Q2 4-4-6-4
duplex — was a relative success. One was built in 1944, with
25 more in ’45, all by Altoona. Basically a 4-10-4 with altered
steam distribution, the rigid-frame Q2 could provide more
than 100,000 pounds of tractive force, plus another 15,000
pounds with the booster cut in. The PRR trademarks were
there, but so were other hallmarks of modern steam: feed-
water heaters, front-end throttles, roller bearings. “[The]
long-boilered Q2s were as exotic as their class designation im-
plied,” wrote Trains Editor David P. Morgan.
But not as exotic as the S2 turbine. Built by a consortium of
PRR, Baldwin, and Westinghouse, No. 6200 was a gallant effort
to sustain the coal-fired locomotive and stave off the diesel.
Supported by a unique 6-8-6 wheel arrangement, the S2 bor-
rowed from marine practice, delivering its steam to a direct-
drive turbine geared to the two center axles, with power distrib-
uted to the other drivers via side rods. It was said to achieve
high boiler efficiency, but it also had difficulty delivering ef-
fective power through all speed ranges. The S2 had a brief
moment in the sun, speeding passenger trains over the Fort
Wayne Division, but maintenance costs soon caught up with
it. The S2 was retired in 1949 and scrapped soon thereafter.