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| Exhaust System | |
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The exhaust system carries exhaust gases from the engine’s combustion chamber to the atmosphere and reduces, or muffles, engine noise. Exhaust gases leave the engine in a pipe, traveling through a catalytic converter and a muffler before exiting through the tailpipe. Chemical reactions inside the catalytic converter change most of the hazardous hydrocarbons and carbon monoxide produced by the engine into water vapor and carbon dioxide. The conventional muffler is an enclosed metal tube packed with sound-deadening material. Most conventional mufflers are round or oval-shaped with an inlet and outlet pipe at either end. Some contain partitions to help reduce engine noise. Car manufacturers are experimenting with an electronic muffler, which uses sensors to monitor the sound waves of the exhaust noise. The sound wave data are sent to a computer that controls speakers near the tailpipe. The system generates sound waves 180 degrees out of phase with the engine noise. The sound waves from the electronic muffler collide with the exhaust sound waves and they cancel each other out, leaving only low-level heat to emerge from the tailpipe. |
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PUBLIC TRANSPORTATION: • TYPES OF PUBLIC TRANSPORTATION • Buses • Paratransit • Streetcars • Light-Rail Transit • Heavy-Rail Transit • Commuter Rail Transit • Automated Guided Transit • Ferries • DEVELOPMENT OF PUBLIC TRANSPORTATION IN THE UNITED STATES • HISTORY TRUCK: • LIGHT TRUCKS • MEDIUM TRUCKS • HEAVY TRUCKS • TRAILERS • TRUCKING OPERATIONS AND REGULATIONS • HISTORY |
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