PRRís I1s decapod
design was so successful that by 1924, this 2-10-0 was considered the standard
heavy freight hauler of the railroad up until WWII. In 1930, the original I1s
underwent a revision of the cylinder steam vents to admit steam for 78% of the
stroke. This boosted tractive effort from 90,000 to 96,000 lbs and made the new
class I1sa. Through the years, many I1s engines were changed over to the
modified I1sa design. By July 1947, the 598-unit fleet was divided into 109 I1s
and 489 I1sa locomotives. They remained in service until the end of PRR steam in
Decapods outperformed Mikado L1ís by a whopping 41% more horsepower while
consuming 12% less steam. Nicknames for the type included Decs and Hippos, the
latter possibly from the fat boiler.
DID YOU KNOW? The I1sa short tender (90F82) has coal board sides that are bent
inward a few degrees. Even the most expensive of brass models have missed this
detail. BLIís I1sa will properly model this detailóan industry first. Thank
you, PRRT&HS Modeling Committee, especially Bob Johnson, for your keen eyes!