What is an engine composed of?

[VanAniyah]

An engine consists of two major mechanisms and five major systems. The two major mechanisms are the engine block with the crankshaft and connecting rod mechanism, and the valve train mechanism. The five major systems are the fuel supply system, ignition system (which diesel engines typically lack), cooling system, lubrication system, and starting system. An engine is a machine capable of converting other forms of energy into mechanical energy, including internal combustion engines (reciprocating piston engines), external combustion engines (such as Stirling engines, steam engines, etc.), jet engines, and electric motors. The term 'engine' can refer to either the power-generating device or the entire machine including the power unit, with its original meaning being 'a mechanical device that generates power'.