What are the first, second, and third piston rings called?
2 Answers
An engine piston generally has three piston rings. The bottom one is the oil ring, the middle one is the carbon ring, and the top one is the alloy ring. Below is an introduction to the functions of piston rings: 1. Functions of the first and second piston rings: They maintain the seal between the piston and the cylinder wall, effectively preventing seizure caused by gas leakage between the cylinder and the piston or between the cylinder and the rings. They also prevent faults caused by the deterioration of lubricating oil. 2. Function of the oil ring: It scrapes off excess oil from the cylinder and forms a uniform oil film on the cylinder wall, reducing wear on the piston, piston rings, and cylinder. Additional information: Below are methods to identify the quality of piston rings: 1. The working surface of the piston ring should not have scratches, abrasions, or peeling. The outer cylindrical surface and the upper and lower end faces should have a certain level of smoothness. 2. The light leakage of the piston ring should be checked. The total length of light leakage gaps in several places should not exceed 1/3 of the cylinder diameter. Otherwise, the piston ring should be replaced.
The piston rings in an engine are divided into three types, each with its own unique name and function. The first one is called the compression ring, positioned at the very top. Its main job is to seal the pressure in the combustion chamber, preventing any leakage, which ensures the car runs with sufficient power. Back when I worked on cars, I often saw blue smoke or a sudden increase in fuel consumption when the first ring was worn out. Replacing it requires caution to avoid scratching the cylinder walls. The second ring is called the scraper ring, and as the name suggests, it assists in sealing while also scraping off excess lubricating oil to prevent it from entering the combustion chamber and burning, which would otherwise cause the exhaust emissions to fail inspection. The third ring is the oil ring, usually a composite component, responsible for thoroughly scraping oil off the cylinder walls and recycling the engine oil. When these three rings work well together, the engine runs quietly and efficiently. Regular inspection and replacement of the rings are necessary, especially for older cars, as excessive wear can significantly impact performance.
