Union Pacific 4-10-2

Originally an experiment in three-cylindered power, the Union Pacific Railroad commissioned Alco to develop a higher speed, stronger pulling, over-the-road locomotive. With many maintenance problems emanating from the original design, the Union Pacific Railroad rebuilt the locomotives, eliminating the third cylinder and Gressley gear. The rebuilding included immediately noticeable visual features such as a much larger sand dome and a significantly enlarged, completely round smoke box. In their two-cylinder configuration, the locomotives appeared in many system locales, the end of their service occurring in the Kansas Division. Challenger is offering multiple versions of this often overlooked, but important class.

Photo from the collection of Robert Darwin

2520.1 Union Pacific 4-10-2, Locomotive #5090. Modeled as it appeared in the 1950's. The first UP 4-10-2 built by Alco in 1925 and rebuilt by the UP in June 1942, with a total of four air tanks mounted two on each side and with the dual air compressors mounted side-by-side over the fourth driver, with bar type pilot, Boxpok center driver installed, blow down deflector under right side of firebox, 12,000 gallon cylindrical tender with standard capacity, flush-mounted fuel bunker in tender.

2521.1 Union Pacific 4-10-2, Locomotive #5091. "Switcher" version with footboards on pilot and on rear beam of tender, spoke center driver, blow down deflector moved to under right side of firebox, three air tanks mounted high under running boards, dual compressors mounted over center driver, 12,000 gallon cylindrical oil tender with standard-capacity, flush-mounted fuel bunker

2522.1 Union Pacific 4-10-2, Locomotive #5092. This engine depicts the final "Late" 1950's version with bar type pilot, Boxpok center driver installed, blow down deflector moved to under right side of firebox, three air tanks with right rear tank relocated to new position low under running board, dual compressors mounted over center driver, 12,000 gallon cylindrical oil tender with new high-capacity, extended fuel bunker installed.

2523.1 Union Pacific 4-10-2, Locomotive #5094. "Post-War" Standard version, 1946-1950. Wartime hoods removed from all lights, bar type pilot, Boxpok center driver installed, blow down deflector moved to under right side of firebox, three air tanks mounted high under running boards, dual compressors mounted over center driver, 12,000 gallon cylindrical oil tender with standard-capacity, flush-mounted fuel bunker.

2524.1 Union Pacific 4-10-2, Locomotive #5095. "The War Baby." The first engine rebuilt in 1942, modeled as rebuilt with sheet metal hood over headlight and marker lights, bar type pilot, spoke center driver, blow down deflector mounted under left side of firebox, three air tanks mounted high under running boards, dual air compressors mounted over center driver, 12,000 gallon cylindrical oil tender with standard-capacity, flush-mounted fuel bunker.

2525.1 Union Pacific 4-10-2, Locomotive #5096. This engine depicts the final "Late" 1950's version with bar type pilot, Boxpok center driver installed, blow down deflector moved to under right side of firebox, three air tanks with right rear tank relocated to new position low under running board, dual compressors mounted over center driver, 12,000 gallon cylindrical oil tender with new high-capacity, extended fuel bunker installed.

2526.1 Union Pacific 4-10-2, Locomotive #5099. "Late" 1950's version with bar type pilot, Boxpok center driver installed, blow down deflector moved to under right side of firebox, three air tanks with right rear tank relocated to new position low under running board, dual compressors mounted over center driver, 12,000 gallon cylindrical oil tender with standard capacity, flush-mounted fuel bunker installed in tender.