| Portland Terminal S3 1101 at South Portland Maine, May 7, 1984, photo by Chuck Zeiler. Larry Hawkes provided the following information from the book, "Maine Central Diesel Locomotives" by Edwin B. Robertson. It says "CLASS" - S-1, PT NUMBER - #1101, DATE BUILT 10/50, SERIAL NUMBER 78393, purchased from the Greater Portland Public Development Corporation (GPPDC Number 661). Larry believes this to be an Alco S1. I believe it to be an Alco S3. According to Wikipedia, the S1 production ran from April 1940 to June 1950 (550 units), and the S3 production ran from March 1950 to November 1953 (292 units). I base my assumption of the following information from the book, "A Centennial Remembrance", by Richard Steinbrenner (page 310): By 1950, Alco's (Model) 539-engined switcher line had seen 10 years of production. Over this period, only minor changes had been made during production. Among those previously noted were the changes to the radiator shutter assemblies and the addition of exhaust stacks to better prevent exhaust emissions from entering operating cabs. As a final note to Alco's 1950 production line, the switcher line received a modest set of upgrades. The most important was the replacement pf the Blunt truck with the GSC rigid bolster truck, used by all the other builders in their switcher products. In 1949 the AAR adopted this truck as Recommended Practice. In response, Alco followed suit; the 660 hp switcher was designated E1530A, S-3, and the 1000 hp was designed the E1540A, S-4. In addition to the truck change, the S-3 and S-4 body construction was modified to maximize welded assembly and to avoid the use of rivets where possible. Also, rubber moldings were applied to all windows. The end result was a tighter body with less tendency to rattle. |