understanding of the whole engine

An understanding of the operation or purpose of the various parts is necessary for a complete understanding of the whole engine.
Each part or unit has its special function to perform and in conjunction with other parts makes up a gasoline engine.
A person who wants to operate, repair, or otherwise service diesel engines must be able to recognize the different parts by sight and know what their particular functions are.
1）、Cylinder.
The heart of the engine is the cylinder, where the fuel is burned and the power developed.
The inside of the cylinder is formed by the liner, or sleeve.
The inside diameter of the cylinder is called the bore.
The cylinder head closes one end of the cylinder and often contains the valves through which air and fuel are admitted and the exhaust gases discharged.
2）、Piston.
The other end of the working space of the cylinder is closed by the piston that transmits to the crankshaft the power developed by the burning of the fuel.
Piston rings lubricated with engine oil produce a gastight seal between the piston and the cylinder liner.
The distance that the piston travels from one end of the cylinder to the other is called the stroke.
3）、Connecting Rod.
One end, called the small end of the connecting rod, is attached to the wrist pin or piston pin located in the piston.
The other or big end has a bearing for the crankpin.
The connecting rod changes and transmits the reciprocating motion of the piston to the continuously rotating crankpin during the working stroke and vice versa during the other strokes.
4）、Crankshaft.
The crankshaft turns under the action of the piston through the connecting rod and crankpin located between crank webs, or cheeks, and transmits the work from the piston to the driven shaft.
The parts of the crankshafts supported by and rotating in the main bearings are called the journals.
5）、Flywheel
A flywheel of sufficient weight is fastened to the crankshaft and stores kinetic energy during the power stroke and returns it during the other strokes.
The flywheel helps to start the engine and also serves to make the rotation of the crankshaft more or less uniform.
6）、Camshaft
A camshaft driven from the crankshaft by a chain drive or by timing gears operates the intake and exhaust valves through cams, cam followers, push rods, and rocker arms.
Valve springs serve to close the valves.
7）、Crankcase
A crankcase serves to hold together the cylinder, piston, and crankshaft, to protect all moving parts and their bearings, and to provide a reservoir for lubricating oil.
The lower part of the crankcase is called a bedplate.‍