Piston rings seal the combustion chamber. They are set with precision so as to apply the correct pressure on the cylinder wall or liner, which ensures there is a consistent film of oil across the cylinder's working surfaces. This provides sufficient lubrication and protects against wear.Piston rings are a vital engine component since they seal the gap between the piston and the cylinder walls. High quality and long lasting piston rings are a must for all types of engines.While piston rings cost around $50 to $200, replacement cost of piston rings is more than $2000.All types of ship machines and parts get worn out due to continuous usage and working. Proper maintenance and routine checks are necessary to ensure that the machines work for a longer time. In this article, we will have a look at various reasons that lead to cylinder liner wear and how it can be minimised.When the engine is running, the piston moves up and down in the cylinder. When the piston reaches the turning point, it slows down and then accelerates again suddenly. This produces inertia forces that act on the piston. When considered together with the forces generated by the gas pressure, this forms the piston force, which is transferred to the connecting rod and crankshaft. Connecting rods are only perfectly vertical at the upper and lower turning points. The angle of the connecting rod presses the piston against the side of the cylinder wall. The amount and direction of this force constantly change during the combustion cycle, as they depend on the piston force and the angle between the piston crown and connecting rod axis. Pistons are equipped with piston rings. They seal the combustion and working chamber in relation to the crankcase. They also remove the oil from the cylinder walls, thus controlling the oil consumption. Piston rings also discharge the heat absorbed by the piston during combustion to the cooled running surface of the cylinder liner.