Big Boy was designed to meet the specification of a locomotive that could pull 3600 tons over the Wasatch Range unassisted. The locomotive name came about when an unknown ALCO employee chalked the name    Big Boy    on the smokebox of the first locomotive in the series. Known as the 4000 class by those who operated them, the Big Boys performed spectacularly at the job for which they were designed. A marvel of mechanical design, Big Boys could run up to 80 MPH. When they were retired, 8 out of the original 25 Big Boys were preserved. Union Pacific Railroad is restoring Big Boy #4014 to operating condition.