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Automotive glossary: What is a Petrol Engine or Gasoline Engine?

Petrol Engine
Definition of Petrol Engine: All motorcycles and most cars are driven by gasoline engines. In these, a highly inflammable liquid (gasoline, but also natural gas, liquid gas or hydrogen) is gasified, mixed with air and afterwards driven to explosion. Then the explosion pressure drives a piston, which moves an axis (crankshaft) into rotation via a crank mechanism. Then the crankshaft is connected with the driving wheels and drives the vehicle. Gasoline engines (also called petrol engines) work after two possible procedures: As a four stroke engine (predominantly) or as a two stroke engine. Nowadays the latter are virtually not used in cars anymore, but only with motorcycles with low cylinder capacity (this is the piston displacement, the volume, which the piston gives free when driven by the explosion), lawn mowers, chain saws etc. Two stroke engines have a simpler design than four stroke engines, the gas mixture is soaked into the combustion chamber in the first operation (stroke), and in the second stroke the explosion occurs, then the working cycle restarts. A stroke corresponds, just as with the four stroke engine, half a rotation of the crankshaft. So with the two stroke engine there is one explosion per revolution, while with the four stroke engine there is only one explosion every second rotation. With the four stroke engine a cycle runs off as follows: In the first stroke, the air gas mixture is soaked in into the combustion chamber, as the piston is pulled down by the crankshaft. (With gasoline direct injection engines, however, only air is soaked in, the gasoline is injected directly into the combustion chamber). Then the crankshaft turns on half a rotation, thereby drives the piston upwards again, and so the mixture is compressed, which increases the energy efficiency of the engine. In the third stroke the actual actuation occurs, while the gas mixture is brought to explosion by a spark and drives the piston down again. When the piston comes upwards again in the fourth stroke, it pushes the burnt waste gas outside. Otto is the name of the inventor of this kind of engines. The diesel engine works much like the four stroke engine, apart from that the diesel is injected directly into the combustion chamber, and the diesel air mixture is lit not by a spark, but auto ignites at the right moment by being compressed.

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