| A type of heat engine that changes chemical energy in fuel and air into mechanical energy. A mixture of fuel and air is drawn into a cylinder as a close-fitting piston moves downward. The valve through which the fuel-air mixture entered the cylinder closes, and the piston moves up, compressing the mixture. As the piston nears the top of its stroke, the compressed mixture is ignited, and it burns. The burning gases heat the air in the cylinder, and as it expands, it pushes the piston downward. The reciprocating piston is connected to a crankshaft throw by a connecting rod. As the piston moves up and down in the cylinder, the connecting rod rotates the crankshaft. |
