High Quality Content by WIKIPEDIA articles! Under the Whyte notation for the classification of steam locomotives, 4-8-0 represents the wheel arrangement of four leading wheels on two axles (usually in a leading truck), eight powered and coupled driving wheels on four axles, and no trailing wheels. The type was nicknamed the Mastodon or Twelve-wheeler in North America. Mastodon (No. 229) was the unofficial name of Central Pacific Railroad`s first 4-8-0, which was built in 1882 at the Sacramento Locomotive Works.