The distinctive, rhythmic "chuff-chuff-chuff" of the locomotive is a uniquely steam-powered sound, often called the "music of the Americas" (it appears in the rhythms of Antonin Dvorak's Symphony from the New World. This choo-choo sound comes when exhaust steam is released by each valve stroke into the blast pipe embedded in the bottom of the smoke box.
Quick facts
Smokebox practicum
Smokeboxes in England
No smoking here