Piston Rings: What Are They and How Do They Work?

The piston ring serves a crucial purpose within your equipment’s engine. Composed of various precise components, each part plays an important role in the engine's efficient operation. Thus, despite being a small element, the piston ring is vital.

What is a Piston Ring?  

A piston ring is a ring-shaped metallic component that attaches to the circumference of a piston, which is found in combustion engines. There are different types of piston rings, each serving slightly different purposes. The various types of piston rings include:

Compression Ring  

The compression piston ring is positioned closest to the piston head and is designed to prevent gas leakages during the combustion process by sealing the combustion chamber.

Wiper Ring  

This type of piston ring is situated between the oil and compression rings. It provides additional sealing support to the combustion chamber (assisting the compression ring) and wipes excess oil from the cylinder wall, further supporting the oil ring.

Oil Ring  

Located closest to the crankcase within the engine, the oil ring is designed to maintain the efficient function of the engine’s oil reservoir. It ensures a thin layer of oil remains on the cylinder throughout the piston’s movement. The oil ring also returns any excess oil to the engine’s oil reservoir by wiping off the oil and allowing it to flow through the ring opening into the sump.

How do Piston Rings Work?

Understanding that there are different types of piston rings, they all have different ways of working in accordance with their specific individual functions. The primary piston ring functions can be found below:

Oil Lubrication Control

One of the primary functions of piston rings is to control lubrication. Adequate lubrication between the piston and the cylinder is crucial, as increased lubrication significantly reduces the risk of wear and tear. The piston ring creates a thin layer of oil between these surfaces as it wipes the oil. Additionally, the piston rings discard any excess oil into the sump. This process helps maintain oil consumption at an acceptable level and reduces harmful emissions.

Gas Sealant

Another primary function of a piston ring is to create a strong seal that contains gases within the combustion chamber. This is essential because the pressure from the combustion gases in the crankcase drives the piston, generating crankshaft rotation. Therefore, it is crucial to control and contain these gases as tightly and efficiently as possible.

Heat Transfer

Piston rings are designed to transfer heat away from the hot piston into the engine's cylinder wall. Once the heat energy is carried into the cylinder wall by the piston ring, it is then transferred to the engine's coolant. This function is vital for maintaining the stability of the piston and appropriate temperatures within the engine.

Additionally, piston rings play a crucial role in the performance efficiency of engine crankcases. They serve as a primary defense barrier for various engine components, including providing a seal within the combustion chamber.