We usually divide the engine into a main engine(2 stroke engine / low speed engine) and an auxiliary engine (4 stroke engine / medium speed engine) in the shipbuilding. The main engine serves as a prime mover of ship with a propeller and an auxiliary engine serves as a generator on board.

The material of cylinder liner is grey cast iron such as Takalloy C, GG25K and GJL 250 which are made of steel and alloy of nonferrous metals. These castings require a abrasive resistance and wear resistance in order to meet high demands imposed by piston running characteristics, high operation pressure and corrosive elements.
The cylinder liner is 460mm to 980mm in bore size, 2000kg to 9000kg in weight and 1680mm to 3640mm in length. The casting of cylinder liner weighs 4000kg to 20,000kg.

Based on the cylinder quantity of the main engine, 5 to 14 cylinder liners are equipp-ed.
The cylinder liner has a major influence on the safety and performance of the ship as one of and important items. In addition, it should be replaced periodically due to a friction and abrasion between liner and piston ring during the running.