PRR S1
The
Pennsylvania Railroad's class
S1 comprised a single
steam locomotive of
6-4-4-6 wheel arrangement in the
Whyte notation, the only locomotive of such arrangement ever constructed. The S1 was a
duplex locomotive: it had two pairs of
cylinders, each driving two pairs of
driving wheels, but its driven wheelbase was rigid, unlike similar-looking
articulated locomotive designs. The locomotive was displayed at the
New York World's Fair of
1939, lettered
American Railroads rather than
Pennsylvania Railroad. The
streamlined shell was designed by
Raymond Loewy.
The S1 was the largest express passenger locomotive ever constructed, and its cast steel
locomotive bed by General Steel Castings was the largest ever made. The six-wheel
leading and
trailing trucks were added as the locomotive's design became too heavy for four-wheel units, but the locomotive was still overweight by a significant margin. The vast boiler was the largest the PRR ever built. The locomotive was so large, in fact, that it could not fit on most of the PRR system. In its brief service life it was restricted to the main line between
Chicago, Illinois and
Crestline, Ohio; it was based at the Crestline enginehouse. For display at the New York World's Fair, it took a circuitous route over the
Long Island Rail Road; many obstacles had to be temporarily removed, and others passed at a slow crawl.
Crews liked the S1, partly because of its very smooth ride. The great mass and inertia of the locomotive soaked up the bumps and the surging often experienced with duplex locomotives.
It was hoped that the locomotive could haul 1,000 tons at 100 miles per hour, but this goal was not reached. Furthermore, the locomotive's extreme length limited its usefulness as it was incapable of negotiating curves on most lines of PRR track. No further S1s were built. PRR instead turned its attention to the
T1 class of
4-4-4-4 duplex locomotives, but they also met with limited success.
This engine is suspected to be the fastest steam engine ever built.
The S1 appears in the
Sandman comic series, book IX.
Image:PRR S1.jpg|The S1 at the New York World's Fair of 1939Image:PRR-S1-Loewy.jpg|Industrial designer Raymond Loewy stands on the front of the S1.Image:PRR S1 detail.jpg|Detail view of the driving wheels and cylinders; note the rollers upon which the wheels rested while on display.*
PRR locomotive classification
