It is an important component which provides the sealing between the engine combustion room and sump while the vacuuming, compression, explosion and sweeping processes are forming in the cylinder during the running of the motor.

Motor piston rings prevent the increase of the high temperature of the engine which occurs by the combustion of fuel by transferring to the cylinder and thus to the cooling water. The ignition piston ring is the one contributing the sealing most as it is exposed to the highest gas pressure effect. The pressure decreases on the subsequent piston rings. The reason for using the oil rings is to provide the scraping of the extra lubrication oil applied to the surface of the cylinder block or liner by hitting effect or mechanical lubricators to the sump and provide a thin oil layer on the liner surface. 

Therefore, the danger of the extra lubrication oil to be taken into the combustion room and being combusted is prevented. At the meantime, the lubrication of the upper parts of cylinder liner and compression rings is also constituted by these rings which are at the upper course of the piston in order to provide a better lubrication.

The numbers of the rings which are placed on the pistons can vary as per the engine types, revolution and powers. The use of 3-4-5 ringed Pistons are very common. Some of the rings have scraping ratchets on them. The oil scraped by these ratchets is sometimes taken into the pistons and from there discarded to the sump.The rings are manufactured in different designs as the cross section profiled and spring shapes ensuring the compression power as per the preference of the engine manufacturers.