Piston and connectiong rod (Wartsilla 18V46 C4)

The connecting rod is a three piece-piece design to allow removal of piston and connecting rod. Extensive research and development has been carried out to develop a connecting rod in which the combustion forces are distributed over a maximum bearing area and where the relative movements between mating surfaces are minimized.

The connecting rod is forged and machined with round sections of alloy steel. All connecting rod bolts are hydraulically tightened. The big end bearing and gudgeon (piston pin) pin bearing are of tri-metal design.

Between the upper part of connecting rod (4) and big end (6) there is a compression shim (5). Oil is led to the gudgeon pin bearing and piston through a bore in the connecting rod.

Piston and connecting rod

2. Piston, upper part

3. Piston lower part

4. Connecting rod, upper part

5. Compression shim

6. Big end bearing housing, upper part

7. Big end bearing housing, lower part

8. Gudgeon pin

9. Securing ring

10. Connecting rod stud

11. Connecting rod nut

12. Big end bearing housing stud

13. Big end bearing housing nut

The piston is of a composite type with a nodular cast iron skirt and a forged steel crown screwed together. The space between the crown and the skirt is supplied with lubricating oil for cooling the crown by means of a cocktail shaker effect.

LO Passage

Lubricating oil is led from the main bearing through the drillings in the crankshaft to the big end bearing, and further through the drillings in the connecting rod, gudgeon pin and piston skirt up to the cooling space and from there back to the oil sump. Part of the lubricating oil is led out from the piston skirt through special nozzles to lubricate the liner.

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