Reciprocatingmoottorit

Reciprocatingmoottorit, or reciprocating engines, are machines that convert heat energy into mechanical work through pistons moving back and forth in cylinders. The linear motion of the pistons is transformed into rotational motion by a crankshaft connected via a connecting rod.

Most common today are internal combustion piston engines, which use either four-stroke or two-stroke cycles. In a four-stroke cycle, the intake, compression, power, and exhaust events occur over four piston movements; in a two-stroke cycle, these processes occur over two strokes, offering higher specific power but typically higher emissions and more wear. Spark-ignition engines run on gasoline, while compression-ignition engines run on diesel.

Historically, reciprocating engines evolved from steam engines and were adapted for internal combustion in the late 19th century, with key developments by engineers such as Otto and Diesel. Today they power most road vehicles, motorcycles, boats, small aircraft, and stationary generators, although electrification and turbine engines are increasingly used in some sectors.

Advantages include a favorable power-to-weight ratio, proven reliability, and broad availability of fuels and components. Disadvantages include emissions, fuel efficiency that varies with load, mechanical complexity of moving parts, noise, and vibration. Modern designs mitigate these through turbocharging, direct injection, variable valve timing, advanced lubricants, and exhaust aftertreatment.

Configurations vary widely: inline, V, or flat cylinder banks; aluminum or steel construction; and multi-cylinder arrangements. Maintenance emphasizes pistons and rings, valves, cranktrain, lubrication, cooling, and timing systems.