WÄRTSILÄ PAAE051728, Instruction Manual

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11.3 Connecting rod and piston
11.3.1 Description of connecting rod and piston
The connecting rod is of a three-piece design, so called “Marine
type connecting rod”. The combustion forces are distributed over
a maximum bearing area. The relative movements between mat-
ing surfaces are minimized.
The connecting rod is forged and machined of alloyed steel and splitted
horizontally in three parts to allow removal of piston and connecting rod
parts. All connecting rod bolts are hydraulically tightened.
The piston is of the composite type with an nodular cast iron skirt
and a forged steel crown screwed together. The space, formed between
the crown and the skirt, is supplied with lubricating oil for cooling of
the crown by means of the cocktail shaker effect. The lubricating oil is
led from the main bearing, through the drilling’s in the crankshaft, to
the big end bearing, and further through the drilling’s in the connecting
rod, gudgeon pin and piston skirt, up to the cooling space, and from
there back to the oil sump.
Note! Always handle the pistons with care.
The piston ring set consists of two chrome-plated compression
rings and one spring-loaded oil scraper ring.
Connecting rod parts
11.3.2 Removing of piston and upper part of con-
necting rod for overhaul
1 Remove both crankcase covers adjacent to the con-
necting rod concerned on both side of engine.
1
2
3
4
5
1. Connecting rod, upper part
2. Shim
3. Big end, upper half
4. Big end, lower half
5. Big end
Fig 11-2
4011019601
11 Crank Mechanism: Crankshaft, Connecting Rod, Piston 32-200020
11 - 4 WÄRTSILÄ 32