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everything about types of piston rings: Ultimate Guide

In the realm of engine components, three primary types of piston rings are frequently employed – the compression ring, wiper ring, and oil ring.

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In the intricate world of engine components, piston rings play a pivotal role. These are small, yet essential parts designed to seal the combustion chamber, regulate oil consumption, and facilitate heat transfer. Their functionality is paramount in maintaining the overall health and efficiency of an engine.

Piston rings may be small in size, but their importance cannot be overstated. They are integral to engine performance, fuel efficiency, and durability. Without them, engines would consume more oil, lose power, and eventually fail. In essence, piston rings are the silent heroes, working tirelessly behind the scenes to keep your engine running smoothly and efficiently.

In this article, we will learn about the different types of piston rings.

everything about types of piston rings ultimate guide

role of piston rings

Piston rings are circular metal bands that fit into the grooves on the outer diameter of a piston. Their primary function is to create a seal between the piston and the cylinder wall. This seal is essential for the engine’s operation, as it serves three main functions:

  • reducing oil consumption: Piston rings prevent excess oil from entering the combustion chamber. By doing so, they help maintain optimal oil levels in the engine, ensuring smooth and efficient operation.

  • maintaining compression: The rings seal the combustion chamber from any leakage during the compression and combustion phases. This seal maintains the necessary pressure for ignition, contributing to the engine’s power output.

  • facilitating heat transfer: Piston rings also transfer heat away from the piston to the cylinder wall, helping to regulate the engine’s temperature.

types of piston rings

Types and functions of piston rings

In the realm of engine components, three primary types of piston rings are frequently employed – the compression ring, wiper ring, and oil ring. Positioned in the groove nearest to the piston head, the compression ring plays a critical role. It ensures the combustion chamber remains sealed, preventing any potential leaks during the combustion process.

what are the 3 types of pistons?

1) Compression ring or pressure ring

Compression rings provide a seal over the piston and avoid gas leakage from the combustion side. A compression ring sits in the first groove of the piston.The function of these rings is to seal the combustion gasses and transfer heat from the piston to the piston wall.

Oil volume is controlled by shearing the oil layer left by the oil ring to provide adequate lubrication for the top compression ring. In addition, it assists in the sealing and heat transfer of the top compression ring.

2) Wiper ring

Wiper rings, also known as napier or backup compression rings, are installed below the ring. Their primary function is to remove excess oil from the lining surface and act as a backup ring, stopping any gas escaping from the top compression ring from leaking further down. Most wiper rings have a tapered surface positioned towards the bottom to provide wiper action as the piston moves toward the crankshaft.

3) Scraper rings/oil control rings

The scraper rings control the amount of lubricating oil passing through the cylinder walls. Positioned below the compression and wiper rings, these rings control the oil film on the cylinder walls.

Oil splashes on the cylinder wall. These scrape oil off the cylinder walls and return it to the crankcase.These rings do not allow oil to pass through the space between the ring face and the cylinder.

In an oil ring, a hole or groove is cut in the radial center of the ring to allow excess oil to flow back to the tank.

Oil rings can be one-piece or two-piece. To increase the contact pressure between the ring and the liner surface, the ring may have chamfered edges outside the lands or facing the combustion chamber to reduce oil consumption by improving oil scraping from the bore.

Two-piece oil control rings consist of a cast iron or profiled steel ring and a coil spring made of a heat-resistant spring that acts on the entire ring circumference to maintain pressure and contact.

types of piston rings-2

Other Piston Rings

In addition to the main types of piston rings, several others serve specific functions within an engine. These include:

  • Scraper rings: These rings perform a similar function to the oil control rings, helping to regulate the oil film on the cylinder walls. They scrape off excess oil and return it to the oil sump.

  • Second compression rings: These rings assist the primary compression ring in sealing the combustion chamber and also ‘wipe’ down the cylinder walls to prevent excess oil from entering the combustion chamber.

  • Napier rings: Named after their inventor, these are a type of second compression or oil control ring. Their design includes a small lip that aids in scraping oil off the cylinder wall.

  • Dykes rings: These are a type of oil control ring with an L-shaped cross-section. Their unique design allows them to exert more pressure against the cylinder wall, improving oil control.

  • Wedge rings: As the name suggests, these rings have a wedge-shaped profile. This design helps improve sealing efficiency.

  • Slotted oil control rings: These rings have slots or holes that allow excess oil to flow back into the sump, enhancing oil control.

  • Keystone rings: Characterized by their trapezoidal shape, these rings provide excellent sealing properties while reducing friction.

  • Gas-nitrided rings: These rings undergo a special gas-nitriding process that hardens their surface, enhancing their wear resistance and longevity.

Piston Ring Materials

In the manufacturing of piston rings, choosing the right material is critical to ensure durability, efficiency, and longevity. The most common forms of alloyed cast iron are chromium, molybdenum, vanadium, titanium, nickel, and copper.Here are some of the most commonly used materials:

  • Cast iron: Known for its excellent wear resistance and compatibility with cylinder materials, cast iron is a popular choice in the production of piston rings. It’s also cost-effective, making it a preferred material for many manufacturers.

  • Steel: Steel piston rings offer superior strength and durability. They’re particularly suited to high-performance engines where the demand for high-speed operation and increased power output is paramount.

  • Ductile iron: This material combines the advantages of cast iron and steel. Ductile iron rings are robust and resistant to heat, making them ideal for heavy-duty applications.


Selecting the right piston ring involves careful consideration of these factors to ensure the longevity and efficiency of your engine. 

At BISON generator parts manufacturers, we are committed to providing you with reliable and efficient piston rings that meet your engine’s specific needs. Our team of experts is always ready to provide further advice or assistance regarding the selection and maintenance of our products.

Explore our range of high-quality generator piston products today. Invest in excellence and experience the difference in engine performance. For more information, don’t hesitate to contact us. Your journey towards optimal engine performance starts with BISON.

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