As delivered to the Rock Island in 1909, this Pacific type (4-6-2) locomotive was one of thirty-three unsuperheated P-31 class (#862-#894) built at Alco’s Schenectady, NY, works. It was originally #887 but was renumbered #886 when it was donated to the City of Peoria, IL, in 1955.
All the P-31s were superheated by the Rock Island in 1917 and the drivers increased by 1” to 74” in diameter. This increased the engine wheelbase from 32’ to 34’ 8” and the driver wheelbase from 12’ 4” to 13’. The engine weight dropped slightly from 227,000 lbs to 226,950 lbs, from 148,000 lbs to 147,750 lbs on the drivers. Cylinders remained at 23” x 28” but the grate increased from 44.8 sq ft to 45 sq ft and the firebox from 179.41 sq ft to 238 sq ft. With 676 sq ft superheating, total heating surface decreased from 3,671 sq ft to 3,555 sq ft. Boiler pressure stayed at 185 psi but tractive effort dropped from 31,907 lbs to 31, 476 lbs.
The superheated engines also had a slightly larger tender, up from 150,000 lbs to 150,640 lbs with water capacity rising from 7,500 gallons to 7,900 gallons. The coal carrying capacity of 13 tons was unchanged.