Cylinder liners, also known as sleeve, it compose the inner part of the cylinders. In cast iron crankcases, cylinders liners are integral or obtained directly cast. When the crankcase is in aluminum alloy, almost always “dry” or “wet” cast iron cylinder liners are used. They are lapped directly by the coolant liquid and can be set at the bottom (in the “open deck” crankcases), or be provided with an upper support edge (in the “closed deck” crankcases). The dry-in cylinder liners are firmly inserted in the crankcase with a slight interference or they can be incorporated at the time of the melting. The inner walls of the cylinder liners must have adequate surface, finish which is usually imparted to them by “crossed smoothing” with rotating abrasive grinding stones. The cast-iron pipes are generally obtained by centrifugal casting.