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Something You Want to Know about Piston

The piston is the reciprocating portion of an automotive engine’s cylinder block. The piston’s basic structure is divided into three parts: top, head, and skirt. The main part of the combustion chamber is the top of the piston, and its shape is determined by the type of combustion chamber used. Flat-top pistons are commonly used in gasoline engines because they have a tiny heat-absorbing area. The shape, location, and size of the pits on the top of a diesel engine piston must be adjusted to the requirements of the diesel engine’s mixture production and combustion.

The Construction

The piston top, piston head, and piston skirt are the three primary elements of the piston.

The piston’s primary role is to withstand the cylinder’s combustion pressure and convey it to the crankshaft via the piston pin and connecting rod. In addition, the piston, along with the cylinder head and the cylinder wall, forms the combustion chamber. Landtopmall provides pistons for Kubota v3800t.


Because the piston top is a vital part of the combustion chamber, it is frequently shaped in various ways. Because the combustion chamber is compact, the heat dissipation area is limited, and the manufacturing process is easy, most gasoline engine piston tops are flat or concave. In two-stroke gasoline engines, raised top pistons are prevalent. Diesel engine piston caps are frequently formed of various materials.

The section above the piston pin seat is known as the piston head. The piston head has a piston ring to prevent high-temperature, high-pressure gas from entering the crankcase and oil from entering the combustion chamber; the piston head absorbs the majority of the heat received by the piston top. The part is delivered to the cylinder, which is then delivered to the cooling medium.

Several ring slots are carved into the piston head for installing piston rings. The number of piston rings is determined by the seal’s requirements, which are linked to engine speed and cylinder pressure. A high-speed engine has fewer rings than a low-speed engine, while a gasoline engine has fewer rings than a diesel engine. Gasoline engines typically have two air rings and one oil ring; diesel engines have three air rings and one oil ring, and low-speed diesel engines have three to four air rings. The height of the ring belt should be reduced as much as possible to reduce friction loss, and the number of rings should be reduced under the condition of assuring sealing.


The piston skirts are all the pieces below the piston ring groove. Its purpose is to guide the piston as it reciprocates in the cylinder while also absorbing side pressure. The action of the gas pressure in the cylinder bends and deforms the piston when the engine is running. Due to the significant amount of metal at the piston pin, the amount of expansion of the piston pin is greater than that of other areas after the piston is heated. Under the influence of side pressure, the piston will also create extrusion deformation. As a result of the foregoing deformations, the piston skirt section becomes an ellipse with its major axis pointing in the direction of the piston pin. Furthermore, the thermal expansion of each part is great at the top and modest at the bottom due to the unequal distribution of temperature and mass along the axis of the piston.

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