A Pennsylvania Railroad I1 Class #4525 (weighing in at over 386,000 pounds) being hoisted up at the railroad’s Altoona Works; date unknown.
The Pennsylvania Railroad’s I1 Class were the largest 2-10-0 “decapod” type locomotives ever built in the United States. With a tractive effort of between 90000 and 96000 pounds-force, the locomotive was designed specifically for the Pennsy’s heavy-duty trackage.
However, the I1s were considered a nightmare by their crews as they were rough-riding and their small driving wheels and lack of counterweights made them prone to slipping. Despite this, almost 600 would be built between 1916-1923 and would remain in service as one of the more dominant freight locomotives until the railroad ended all steam operations in 1957.
(This website has tons of pictures from the PRR’s Altoona Works throughout the era of steam and into today as the area is still being used by the Norfolk Southern Railroad.)