Of course, the chain saw uses gasoline as an important source of power, of course, the main function is still used for logging. The power part of the chain saw is a gasoline engine. The body of the chain saw engine is the main part that generates power. It directly determines the function and service life of the chain saw. The body of the chain saw engine is mainly composed of cylinders, pistons, connecting rods, crankshafts, and crankshafts. It is composed of box and flywheel.

First,cylinder
Chain saw engine
The cylinder is a cylinder for the piston to move in it, and the combustion explosion of the mixture is in this place. In order to increase the wear resistance of the inner wall of the cylinder and increase the heat dissipation of the cylinder, the cylinder is generally made of aluminum alloy castings, and the inner wall is chrome-plated. The upper part of the cylinder is the main work place of the chain saw engine, so the upper part of the cylinder wears quickly. At the same time, the connecting rod swings left and right when moving in the cylinder, and the left and right sides have a large degree of wear. If worn to a certain degree, the cylinder is scrapped.

Second, the piston
Chain saw engine
The piston bears the pressure of the working gas of the chain saw engine, performs reciprocating motion, and transmits the pressure to the crankshaft mechanism through the connecting rod. At the same time, it is driven by the connecting rod and crankshaft (by inertia force) to complete the work of air intake, compression and exhaust. The piston of a piston engine is at most arc-shaped to facilitate the flow of the mixed gas. The upper part of the piston is subjected to a higher temperature, so the diameter of the upper part is smaller than the diameter of the lower part during manufacture, which is used as a reserve for expansion. In order to ensure the close combination between the piston and the cylinder wall and ensure good compression, there are 2-4 piston rings in the ring groove on the piston, and the opening gap is 0.10-0.15mm as the allowance for expansion.

Three, connecting rod
Chain saw engine
The connecting rod is used to connect the piston and the crankshaft of the engine, transfer the gas pressure received by the piston to the crankshaft, and change the reciprocating linear motion of the piston into the rotational motion of the crankshaft. The small end of the connecting rod is connected with the piston, and the big end is connected with the crankshaft. 

Fourth, the crankshaft
Chain saw engine
The crankshaft uses cylinders, pistons and connecting rods to change the linear motion of the pistons into rotary motions. At the same time, it can push the piston to make a reciprocating linear motion. In order to simplify the manufacture of the crankshaft, the crankshaft of the chain saw engine is composed of two half shafts, two crank arms and a crank pin. The end of the half shaft and the crank pin are pressed into the crank arm, and finally connected to form a crankshaft. The crankshaft is generally installed in the crankcase by means of ball bearings.

Five, flywheel
The basic function of the flywheel is to maintain the balance of engine operation. In addition, the flywheel makes the engine easy to start. When the explosion stroke begins, the rotational energy of the crankshaft is stored, and before the piston reaches the maximum through ignition, top dead center, and mixed gas compression, the flywheel releases the energy to make the crankshaft continue to rotate.

Six, crankcase and flywheel housing
Chain saw engine
The crankcase is the base of the engine, on which the components and parts of the engine, such as cylinders, ignition devices, etc., are respectively installed. The crankcase of the two-stroke chain saw engine not only allows the rotating parts of the engine to rotate in it, but also functions as a scavenging pump. In order to maintain a certain pressure in the engine body and prevent the mixed fuel or steam from running out of the engine body, an oil seal is set between the crankshaft and the axle box. There is a flywheel housing on the outside of the flywheel for protection. There is a spiral duct on the outside of the flywheel housing, which is part of the engine cooling system of the chain saw. Therefore, the flywheel housing is also the housing of the blower.