Repair parts - 17/02/2021
Correct engine operation is one of the fundamental factors for ensuring the performance of earth moving machines like excavators, mini-excavators, bulldozers, front end loaders, and dumpers, which are typically subjected to intense operation.
Choosing and carefully maintaining engine components can extend the operating life of machines, keep down maintenance costs, and increase productivity by reducing breakdown times. This article illustrates how and why cylinder liners, also known as cylinder sleeves, can make a valuable contribution.
Liners are cylindrical surfacing elements capable of retaining a thin film of oil on the inside surface. When inserted into the cylinders of the engine block, they protect it from wear and from the sliding action of the pistons. The engine blocks of industrial machines, unlike less demanding applications, normally have cylinder liners rather than allowing the pistons to move in direct contact with the walls of the engine block.
There are two main types of liner. The first type has no direct contact with the wall of the engine block cylinder, and the liner is washed with a flow of cooling liquid. For this reason they are called “wet" liners. The second type are known as “dry” liners, or “sleeves“, and are thin bushings fitted inside the engine block with the outside wall in direct contact with the engine block cylinder.
Engine manufacturers use lined cylinders because of the advantages this system offers, the main reasons being:
Liners are subjected to many types of loading pressures:
For all these reasons the manufacturing process for these components is very important and their design must satisfy precise specifications in order to protect the engine and extend its operating life. These include:
A fundamental feature of liners for reducing friction and extending engine life is a criss-cross pattern of grooves on the inside wall. This grooved surface maintains an adequate quantity of oil on the inside wall of the liner, which ensures sufficient lubrication at the contact point between the piston rings and the liner. The correct angle of intersection for the groove of the walls is generally estimated at about 45°, since this promotes even lubrication and consequently extends the duration of the surfaces. However, there are cases in which different angles are created for specific materials and forms of use.
Finally, other factors that help to increase resistance, and limit wear on the liner surfaces are rolling of the flange and the anti-corrosive surfacing of the outside wall.
The main steps for correctly fitting liners inside cylinders are listed below, along with a few precautions and techniques to avoid faults and premature wear.
The choice and correct use of just one small component can make all the difference for the performance and operating life of earth moving machines. This is why it is vital to find a reliable expert partner.
ITR Usco offer a wide range of sleeves, with bores from 94 mm to 170 mm, for Caterpillar®, Komatsu®, Volvo®, Hitachi®, and JCB®. Contact our staff for more information on the most suitable type and materials for your applications.