What is the Cylinder Liner? Types and Function.

 

cylinder liners

Cylinder Liners-

The problem of cylinder wear is considerable and this has been solved by the use of cylinder liners. The cylinder liners are in the form of barrels made of special alloy iron containing silicon, manganese, nickel, and chromium. They are cast centrifugally. It is now customary to fit cylinder liners on the engines of cars and commercial vehicles. These liners are of the oil hardening type and offer considerably longer life for the engine. The cylinder liners are of two types—dry liners and wet liners.

Types-

The cylinder liners are of two types- Dry liner and wet liner. Dry liners are used in engines before but wet liners are better than dry liners. Let's talk about the different liners-

Dry Liners-

Dry liners

A dry liner is made in the shape of a barrel having a flange at the top which keeps it in position in the cylinder block)The entire outer surface of the dry liner bears against the cylinder block casting and hence has to be machined very accurately from the outside also. Thus, it is not in direct contact with the cooling water and hence is known as a dry liner. Its thickness ranges from 1.5 mm to 3 mm. It is used mostly for reconditioning worn cylinders.

Wet liners-

wet liners

A wet liner forms a complete cylinder barrel. It is provided with a flange at the top which fits into the groove in the cylinder block) At the bottom, either the block or the liner is provided with grooves, generally, three in number, in which the packing rings made of rubber are inserted. The liner is in direct contact with the cooling water and hence is known as a wet liner. The outer surface of the liner does not require accurate machining. Wet liners are thicker than dry liners, ranging from 1.5 mm to 6 mm.

Comparison -

There is a huge difference between the dry liner and the wet liner. The comparisons are-
1. A wet liner can be replaced easily and for this purpose, there is no need for any special tool or equipment.

2 A wet liner is in direct contact with circulating water and hence reduces piston temperature.

3. A wet liner is free to expand without any restraint since it is held by a flange only at the top.

4. A wet liner has to be provided a leakproof joint between the cylinder casting and the liner. whereas there is no such requirement in a dry liner.

5. A wet liner requires simple construction of the cylinder block, without any accurate machining on the inside surface of the cylinder block.

6. A wet liner can be finished accurately before fitting, whereas a dry liner cannot be finished accurately before fitting because of the shrinkage stresses produced.

Functions-

A cylinder liner performs various tasks inside an IC engine. The functions are-

Sliding surface-

The formation of the sliding surface is more important than other things. The cylinder liner, in which the piston reciprocates, just needed to be slippery. The liner needed to be lubricated all the time to reduce friction and increase better-sliding performance. The alloy also plays a great role in sliding.

Wear and tear-

The cylinder liners have an anti-galling property which helps the cylinder liner to reduce wear. It also protects the piston rings which are always attached to the liners. If the cylinder is clogged then the liner must need to be replaced.

Heat transfer-

The cylinder liners play a role to transfer the heat(generated at combustion) to the atmosphere. In wet liners, the heat is transferred to the water jacket, attached to the cylinder block. If the heat does not transfer, then the clogging probability is increased.