Diesel marine engines - Cylinder liner construction of MAN KZ series ship engine

Diesel marine engines - Cylinder liner construction of MAN KZ series ship engine
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We studied about cylinder liners in our previous article, which are an important part of the marine diesel engines. We learnt about their materials and construction and now we will learn about a specific type of liner namely the MAN KZ cylinder liner and see how it is construction with the aid of diagrams.

The MAN KZ Cylinder Liner

As we had learnt, each cylinder liner is constructed and manufactured in a unique manner based on the requirements, size and the manufacturer. It is not possible to study the construction of all types and makes of cylinder liners in this series yet we will take a look at the construction of MAN KZ engines and see their cylinder liners.

The description can be best understood if you learn it in conjunction with the sketch of the liner given above. As you can make out from the diagram the KZ cylinder liners are not made in a single piece but have a two piece construction. The upper part is lowered in the outer jacket from the top side and is held in place due to the upper flange which in turn is kept pressed by cover studs. The smaller diagram on the top right hand corner of the sketch shows an enlarged view of this upper flange arrangement and how it supports the liner.

As you know the liner has to dissipate a lot of heat which is generated inside the combustion chamber located towards the top of the liner. You also know that heat dissipation increases with the increase in surface area (that is why you spread your cloths to the maximum possible extent while drying) hence the upper section of the liner tube has a provision for increased surface area which is achieved in actual practice by providing ribs at its outer surface.

The space between the outer jacket and the cylinder liner tube is used for circulating jacket cooling water which helps to transfer heat to the jacket water, which in turn is cooled using jacket water coolers in a closed system. But this cooling space requires sealing so that water and gases do not escape and this is achieved through the use of packings, sealing ring and copper ring and this arrangement is shown in an enlarged form in the bottom right hand diagram.

Similarly the lower part of the liner is inserted from below in the jacket and is bolted to the underside of the cylinder jacket. There are eight feed points for supply of lubricating oil which forms a part of the cylinder lubrication system of the main engine. There are lubricating points below the scavenge ports as well and independent pumps are used to supply oil to all these valves.

Sulzer RD

I will not go into the details of the Sulzer RD liner construction but basically it is made out of a single piece unlike the above mentioned MAN KZ which is 2-piece construction. Rest most of the arrangement is quite similar to it. In our next article we will study about the wear in cylinder liner and ways for inspection to find out any possible defects.


Image of MAN KZ Cylinder Liner: Sanyal, D.K. (1998) Principles & Practice of Marine Diesel Engines. Mumbai: Bhandarkar Publications