Engine Technical Tip

About the cam wear of the crankshaft

Deterioration and wear-out of the engine parts will be occurred for a long term engine use. As for this, the main parts of the engine are also similar.

The wear-out of the crankshaft occurs in the contact surface with the metal. As for this wear-out revel is depend on the controlling of the lubricant. The combustion sludge is cleaned from the engine with the lubricant. Afterwards, the sludge is removed with the lubricating oil purifier and the lubricant filter. This sludge is not removed enough if the management of the lubricant is insufficient. The generation of this sludge is greatly different according to the using fuel oil class. As for the sludge generation of a large-scale diesel engine, using heavy oil tends to increase.

The wear-out form of the crankshaft has the special form that is called cam wear besides general wear-out and oval wear-out. This is generated mainly in the crankpin journal.

The reason of the cam wear is an influence by the lubricant supply groove of the metal. This oil supply groove is designed to the opposite side from pressure receiving side, as not to receive the influence by the combustion pressure of the engine. However, contact is caused by the inertia force when the piston is moving from the bottom dead center to the top dead centre, and it is worn out excluding the metal oil groove part for a long term. It is shape on convex that is called this part “cam wear”.

Height of the convex part in JFE regulated of the cam wear is 10μ or more.

There is a following criterion of the presence of the cam wear.

• Visual confirmation of metal condition
  A strong touching occurs in the center of the metal when the cam wear exists. If the cam wear at a dangerous level exists, the copper alloy can be seen in the center metal of all surroundings.
• Visual confirmation with the stretch gauge with specialist.
  Com wear convex can be checked with specialist with color checking paste on the stretch gauge.
• Special easement device “Inch worm” that JFE designed
  The condition can be is judged from the measured value by using a special measuring device that designed by JFE

If the cam wear is confirmed, it is necessary to remove the cam wear.
Most probably case, oval wear-out and general wear-out　of the crankshaft is remained if the cam wear is remarkable. The case, it is necessary to grind the crankshaft to under a size again to make the crankshaft normal. For this repaired work, it is necessary to have engine maker’s supervision to control of the crankshaft condition.

Proper management of the lubricant is the most important to prevent the cam wear and the crankshaft being worn out and it is effective.

If the filter and Purifaiyar that the engine maker specified are maintained according to operation manual, it is enough usually. However, there is some of the case capacity is insufficient, and the performance decreases because of the passing age and etc.. If it is possible, using of large capacity of the filter and Purifaiyar is recommended.

Consumption of lubricant of engine

Heavy fuel of the most inferior class is used as a fuel as for a large-scale diesel engine for the ship. There is a one of the purpose of the lubricant to defend the engine parts from this inferior oil. Therefore, various additives are mixed as for the lubricant, so lubricant for large scale diesel engine is excessive expensive.
The lubricant consumption has a large influence in the operation cost of the ship.

Lubricant consumption and lubricant supply are planned to do the balance with a newly built engine. However the rate of lubricant consumption often increases with the passing age, however there are various opinions about the lubricant consumption.

The wear-out of the cylinder liner is caused to contact with the piston ring. Moreover there is wear-out with the carbon that does the stuck to the piston top ring land called boa polish. Especially, the boa polish happens easily to the engine of the trunk piston type because there are no posture support parts of the piston like the cross head type engine. Also the boa polish is influenced from the thermal deformation of the piston.
Therefore, contact with the cylinder liner is not the same at circumference. In addition, the valve recess structure of the piston also has the influence in thermal deformation.

This boa polish makes the cylinder liner in oval wear-out. Therefore, the piston ring cannot follow to the shape of the cylinder liner that does oval wear-out. Therefore, the lubricant consumption is increased because of the ring not to follow to the oval shape of the cylinder liner.
Finally the piston ring cannot control to the lubricant supply to combustion chamber.

Honing of cylinder liner

The surface of the cylinder liner is processed by a variety of processing methods for keeping the lubricant on the surface of cylinder liner easily.

The honing processing is logically excellent in these processing methods. In addition, there is an advantage that can be processed in the local site.
The managed honing processing can keep long honing effects, and the lubricant consumption can be decreased too.

Moreover, excellent honing processing contributes to shortening the time of the running in of the engine. This managed excellent honing is called plateau honing.
Plateau honing is also mentioning in DIN standard in Germany.

Surface of honing liner that before plateau honing is the one like file, easily expressed.
It is means that it is easy to attack the other party (piston ring) on such a surface.
On the other hand, plateau honing can be expressed as file of wearing out.
That is, it can be said the state without a sharp part on the surface where the other party cannot be attacked.

It can be said that plateau honing is like after running in surface if thinking only the liner in the engine.
To practice, and to evaluate this plateau honing, it is not appreciable in work by the sense. The surface roughness measuring instrument is evaluated by the use Abbott curve.

Plateau honing demanded in our large-scale diesel is different according to the use of the piston ring package. However, the evaluation method is similar.
For our Pielstick engine, we provided controlling value of plateau honing by  technical information.

Just for short form understanding of plateau honing, it is necessary to control to the value of Rpk, Mr1, and Mr2 especially in the evaluation numerical value of the Abbott curve.
It is important to understand the method of evaluating the surface rough to understand honing.

Comming soon

Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon

Comming soon

Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon Coming soon