轧轧声发出轧轧声,轧轧响著前进
chug n : the dull explosive noise made by an engine v : make a dull, explosive sound; "the engine chugged down the street" [also: {chugging}, {chugged}]
chugTo run slowly; to {grind} or {grovel}. "The disk is chugging like crazy." [{Jargon File}] (1995-03-25)