This historic term describes the steam locomotives that originally replaced animal power on the rails. Crews and the general public used the name to capture the raw mechanical power and heavy metal construction of early steam traction. While no longer used as a serious technical designation, the phrase remains a common cultural reference for classic steam engines operating on heritage lines.
Heard on the job
We get a lot of foamers down at the crossing whenever that old iron horse comes through on an excursion run.
Insider tip
Railroaders almost never use this term in serious shop talk, reserving it mostly for dealing with the public or historical societies.