Passing vehicles with diesel engines. Distinct valve knock and low-frequency engine rumble. Consistent mechanical rhythm with occasional gear shifts. Medium to slow speed, dry exterior recording with slight Doppler effect. Captures industrial vehicle motion with emphasis on engine detail. Usage: film, games, foley, documentary, transport. Valve Knock Drive 01-0:14 Valve Knock Drive 02-0:17 Valve Knock Drive 03-0:23 Valve Knock Drive 04-0:17