was reissued as the 671rr (671 rerun). The 681 returned the next year. In 1954 and 1955, another turbine, numbered 682, was released. The 682 was basically a 681 but with valve gear on the wheels and a white stripe painted on both sides. References External links The Duplex and Experimental Steam Engines of the PRR Pennsylvania Railroad S2 steam turbine "Modern Power For Today's Trains" - A promotional booklet put out by the PRR in 1949 showcasing the railroads latest motive power. "The Keystone" Magazine - Autumn 2012 Volume 45 - Number 3 - The S2 Turbine 686 S2 6-8-6 Steam Turbine (2014, in Russian) Pennsylvania Railroad patent drawings (January 20, 2012 Classic Trains Magazine) "Presenting a Line of Modern Coal-Burning Steam Locomotives, December 1944" - A promotional booklet put out by the PRR in 1949 showcasing the railroads latest steam locomotives. Steam turbine locomotives Baldwin locomotives 6-8-6 locomotives Steam locomotives of the United States S2 Individual locomotives of the United States Experimental locomotives Scrapped locomotives Unique locomotives Passenger locomotives Standard gauge locomotives of the United States