Everything you need to know about car pistons

Car pistons (also known as piston rings) are an important part of a car engine, it provides many functions that no other device can replace. Without this detail, the car engine is almost unable to function.

To know how important the piston is? What is the function and cause of piston ring damage? Let’s find out with CarOn in the article below.

What is an automobile piston?


Piston is a part of a car engine. Piston together with other parts such as cylinder and cylinder cover form a combustion chamber, and at the same time transmit the force of the gas to the connecting rod, as well as the piston receives force from the connecting rod. to compress air. In addition, in some 2-stroke engines, the piston is also responsible for opening and closing the intake and exhaust ports of the combustion mechanism.

Working conditions of automobile pistons

As a part of an automobile engine, the piston’s working conditions are also extremely harsh, specifically as follows:

The load of dynamic force is large and cyclical:

– High pressure, up to 420 kg/cm2 or more

– Large inertial force, especially in high-speed engines

High thermal load

Due to direct contact with combustion gases with temperatures of 2200 – 2800 K, the piston top temperature can reach 500 – 800 K. Due to high temperature, the piston loses its strength or gets stuck or cracked, reducing the coefficient of friction. killing, causing explosion…

Great friction and chemical corrosion

Due to the horizontal force N, there is large friction between the piston and cylinder. Lubrication conditions here are very difficult, usually only by swinging, so it is difficult to ensure perfect lubrication. On the other hand, due to frequent direct contact with corrosive substances such as hydrochloric acids, the piston is also subject to chemical corrosion.

Automotive piston structure


The main parts of the piston include: Piston ring, piston pin, piston skirt, piston head, bearings and connecting rod.

  • Piston ring: The piston rings seal the gas in the cylinder, so that the combustion gases generated at the time of ignition do not enter the gap between the cylinder and piston. This helps maintain air compression between the cylinder wall and the piston.
  • Piston pin: The piston pin, also known as the gudgeon pin or wrist pin, is used to connect the piston to the small end of the connecting rod. This part has a hollow cylindrical structure (the outer surface is cylindrical, and the inner surface is grooved) to reduce latch weight.
  • Piston skirt: Piston skirts are often made of cast iron to increase wear resistance and self-lubricating properties. The piston skirt is designed with grooves to install piston oil rings and compression rings.
  • Piston head: The piston head is also called the top or dome of the piston. This part is in direct contact with gas and must withstand high temperatures. Therefore, to avoid melting, piston head parts are often made from special alloys, including steel alloys. In addition, the piston head is made with grooves and chambers that help create a swirl, improving combustion.
  • Piston bearings: This is the piston part located at the points where the rotation of the shaft occurs. Therefore, piston bearings are often designed in a semicircular shape to fit easily into the holes on these points. In addition, piston bearings are made from lead, copper, silicon aluminum, etc. with coating to improve hardness and support loads from the movements of the connecting rod and piston.
  • Connecting bar: The connecting rod, also known as the connecting rod, is a part of the internal combustion engine that connects the piston to the crankshaft. The connecting rod moves forward, combining with the piston crank to create rotation of the crankshaft.

Operating principle of automobile piston


Although many types and shapes are used, the piston’s principle of operation is the same. It tends to come out and hug the cylinder, thus always experiencing friction during operation.

Accordingly, during the suction stroke, the piston will move upward, close to the wall on the grooves. On the contrary, if the piston moves down, close to the bottom wall of the groove during the exhaust and compression strokes. In the middle of the groove, the system does not lie close to the upper and lower walls but will be rocked back and forth, moving freely as the piston moves up and down continuously.

During the explosion period, compression pressure will push the piston down, close to the bottom edge of the groove to help compressed air move into the gap more easily. At this time, the compressed air will push the pistons close to the cylinder wall, causing them to expand with maximum force, helping to seal the engine combustion chamber.

What types of car pistons are there?

Gas piston

The air piston is responsible for preventing air from leaking down the slots, while also helping to release heat.

This type of piston is designed with many different cross-sections, including beveled top pistons, tapered pistons and bottom tapered pistons. Due to frequent contact with combustion gas, high temperature and chemical corrosion, the beveled top piston is made of a thicker and more durable material than the tapered piston.

The beveled head piston has the effect of holding soot to help prevent it from getting stuck in the groove. Meanwhile, the tapered piston has high contact pressure and the ability to fit quickly with the cylinder but is quite complicated to manufacture.


Oil piston

Oil pistons include two types: spring pistons and 3-ring pistons, which prevent lubricating oil from flowing into the combustion chamber, evenly distributing the amount of oil on the cylinder surface to reduce friction between parts. Unlike air pistons, oil pistons are thicker and have additional holes and oil drainage grooves.

Function of automobile piston

Piston has good hardness, durability and high elasticity to withstand wear under limited friction conditions, ensuring good performance of functions such as:

Maintains air compression between the cylinder wall and piston

Leaking gas not only causes waste but also causes other parts to become fouled or worn. To overcome this, piston rings are created to enclose the cylinder and combustion chamber, separating the space in the cylinder into two parts to prevent combustion gas from leaking into the gap between the cylinder and piston.

Adjust the amount of lubricating oil to prevent scratches

The ignition process causes the piston to move up and down continuously at a frequency of up to thousands of times per minute. During such operation with high temperatures, the amount of lubricating oil will tend to gradually decrease. When this happens, the piston will play a role in adjusting the amount of lubricating oil in the piston to limit friction and operate more smoothly.

Heat dissipation for the engine, supporting Piston operation


Temperatures can reach 300 degrees Celsius when fuel combustion takes place, long periods of time can damage the engine. However, this problem will be limited because the piston ring will transfer heat from the piston to the cylinder, while adjusting coolant to dissipate heat.

In addition, piston rings can also help the piston operate smoothly without tilting, avoiding impact on the cylinder wall, causing engine damage.

Some common applications of pistons


Pistons are widely used in activities such as:

  • Pistons are commonly used in the combustion chamber of IC engines.
  • Used in hydraulic pumps and hydraulic cylinders as ram transmitters or double acting units.
  • Used to push the latch of a self-loading gun.
  • Pistons are used in air conditioners to help circulate fluid.
  • Pistons are used in steam engines to convert steam into energy.
  • Commonly used in automotive parts and equipment.
  • Widely used in air compressors and heat pumps.

Where is a reputable place to have car pistons serviced?

Is a part of the car engine that is not only responsible for coordinating with the cylinder and engine cover to create the combustion chamber but also helps open and close the intake and exhaust ports in two-stroke piston engines.

Due to frequent operation at high temperatures for long periods of time and friction with the cylinder walls, the piston is easily worn and damaged. If an error is detected in this part, users should take the vehicle to a reputable maintenance center to have a technician check and handle it promptly to ensure stable engine operation.

CarOn Pro is one of the most popular car maintenance addresses today. Ensuring product quality as well as service quality, CarOn is confident in giving customers the best experience.

For further information, please contact hotline 0961.247.360 or website https://caronpro.vn/ for the fastest consulting support.

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