The first 4884's were built in 1941 by American Locomotive Co for Union Pacific. They made 20 of the first class, then 5 more in 1944. I think the last one was retired late in 1962. They were know as the "Big Boys" with a 4884 axle arrangement.
Builder: Alco
Fuel: 28 tons
Cyclinders: (4) 23.75 x 32"
Water: 25,000 Gal
Weight: 1,208,000 lbs
Dia. Drivers: 68"
Steam Pressure: 300 lbs
Tractive Effort: 135,375 lbs
