シュッシュッポッポ

adverb taking the 'to' particle

chuff-chuff; choo-choo; chug-chug; puff-puff

Onomatopoeia for the sound of a steam engine, often used in children's contexts or to evoke old trains.

See also: ぽっぽ

• 古ふるい蒸じょう気き機き関かん車しゃがシュッシュッポッポと走はしり出だした。

  The old steam locomotive started off with a chuff-chuff-puff-puff.