page_title: Pennsylvania Railroad class S1
section_title: Retirement
hierarchical_section_title: Pennsylvania Railroad class S1 / Retirement
caption_attribution_description: English: Photo of a Pennsylvania Railroad streamlined steam locomotive T1 class. Note the photo uploaded is of better quality than the one shown in the newspaper scan. A renewal search was done in periodicals for the years 1969 and 1970. There were no listings for the Wilkes-Barre Record. There is no evidence of renewal.
context_page_description: The PRR S1 class steam locomotive was a single experimental duplex locomotive of the Pennsylvania Railroad. It was designed to demonstrate the advantages of duplex drives espoused by Baldwin Chief Engineer Ralph P. Johnson. It was the longest and heaviest rigid frame reciprocating steam locomotive that was ever built. The streamlined Art Deco styled shell of the locomotive was designed by Raymond Loewy.
  The S1 had a unique 6-4-4-6 wheel arrangement, meaning that it had two pairs of cylinders, each driving two pairs of driving wheels. To achieve stability at fast passenger train speeds, articulation was not used. The S1 was completed on January 31, 1939, at Altoona shop, and was numbered 6100.
  At 140 ft 2 ¹⁄₂ in overall, engine and tender, the S1 was the longest reciprocating steam locomotive ever; it also had the heaviest tender, highest tractive effort of a passenger steam engine when built and the largest drivers ever used on a locomotive with more than three coupled axles. The problem of wheel slippage, along with a wheelbase that was too long for many of the rail line's curves, limited the S1's usefulness.
context_section_description: According to an official report from PRR dated December 1, 1945, which is now stored in The Hagley Museum and Library, S1 #6100 was awaiting engine truck repairs at Crestline. It was expected to be returned in service after a few days. This is one of a solid proof that S1 was still in service at least until December 1945. At the time, at least 13 T1 4-4-4-4 were already put into service. 
  The design flaws of the S1 led to only one example being produced. Before S1 was officially put in revenue service, The PRR already ordered a shorter design, the T1 4-4-4-4 T1 of 1942. Unlike her duplexes sisters, PRR S1 didn't install any Poppet Valve Gear, even though it was proposed to install  Franklin Type A rotary cam poppet valve gear when she was already under construction, but such proposal was rejected due to technical difficulties in 1938, this decision unexpectedly prevented a lot of troubles that would have been caused by the problematic Franklin poppet valve gears in S1's service life. The total service years or total service mileage of S1 (from Nov 1939 to March 1940, Dec 1940 to May 1946) was ironically slightly longer than some of her younger duplex sisters.
  
  A time-book belonging to Pennsy engineman Byron Breininger from the Ft. Wayne division records a trip to Chicago on S1 engine #6100 at 8:59 AM on May 5, 1946, this run was possibly one of its last in service. Less than two years later, PRR president Martin W. Clement announced that “By May of this year (1948) we expect all of our through passenger trains west of the electrified territory to be dieselized”. Preservation of S1 was discussed inside PRR's board, but due to the deteriorating financial situation since 1946, S1 #6100 was scrapped in 1949. The PRR continued developing the T1 class of 4-4-4-4 duplex locomotives but wheel slip and mechanical failures also plagued the T1.
caption: Base on the experience gained from S1, PRR improved the design of T1. A total of 52 of them were ordered from 1940 to 1945.
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