0646404 PISTON For HITACHI ZX490-5A

The piston ring includes a gas ring and an oil ring, which are used to seal the combustion chamber, prevent gas leakage, and control the consumption of lubricating oil. Piston rings work in high temperature and high pressure environment, easy to wear, once failure will lead to engine starting difficulties, power shortage and other problems.

The piston assembly is mainly composed of piston, piston ring and piston pin. ‌ The piston assembly is the key part of the engine. It is responsible for converting the pressure generated by combustion into mechanical energy and driving the engine. The piston is the core component of the piston assembly, which bears the gas pressure in the cylinder and transfers the force to the connecting rod through the piston pin, and ultimately drives the crankshaft to rotate and output power. The top of the piston, the cylinder head and the cylinder wall together form the combustion chamber ‌.

The piston pin connects the piston to the small end of the connecting rod and transfers the gas pressure of the piston to the connecting rod to make the crankshaft rotate. Piston pins are usually made of mild steel or alloy steel to ensure their strength and durability. In addition, the structure of the piston includes a top, a head and a skirt. The top is designed to form the combustion chamber, the head is fitted with a piston ring to seal the combustion chamber and conduct heat, and the skirt guides the linear movement of the piston in the cylinder and withstands the side force.