PRR S1 - Construction History

Construction History

In 1937 Pennsylvania Railroad officials decided to build a new passenger locomotive to replace its aging K4s locomotive. The PRR officials also hoped that the new S1 steam locomotive would have performance equal to their GG1 electric locomotive.

In a collaborative effort, the Pennsylvania Railroad, Baldwin Locomotive Works, the Lima Locomotive Works and the American Locomotive Company contributed to the experimental S1 design.

The S1 was the largest passenger locomotive ever constructed, with an overall length was 140 feet 2+1⁄₂ inches (42.74 m). At 77 feet (23 m) long and a weight of 97,600 pounds (44.3 t), the cast steel locomotive bed plate made by General Steel Castings was the largest single-piece casting ever made for a locomotive.

The boiler unit for the S1 was the largest built by the Pennsylvania Railroad. 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. The streamlined Art Deco styled shell of the locomotive was designed by Raymond Loewy, for which he received U.S. Patent No. 2,128,490 The final cost for the S1 was $669,780.00.