The (4000-class) is the largest and heaviest reciprocating steam locomotive ever built, designed specifically to haul massive freight trains over the steep Wasatch Mountains in Utah and Wyoming. Key Features and Specifications

: The 14-wheel tender carries roughly 25,000 gallons of water and 28–32 tons of coal. Where to See a Big Boy Today Union Pacific Big Boy: History & Facts - Ftp

: Generates over 7,000 HP, measures over 132 feet long, and weighs more than 1.2 million pounds.