Cylinder Liner and Piston of marine 2stroke diesel engine

The cylinder liner is fitted inside the bore of the cylinder frame and tightened against the top of the cylinder frame by cylinder cover.
The lower part is free to expand when the temperature increases during the running of the engine. The cylinder liner is cooled by means of a cooling jacket and cooling bores.
The scavenge air ports are located in the lower part of the cylinder liner. The bores for cylinder lubricating quills are located in the area between the cooling jacket and the cylinder frame.
The lubricating oil is supplied through the quills into the cylinder liner to the lubricating grooves. A piston cleaning ring is mounted at the top of the cylinder liner.
This prevents the building up of deposits on the piston top land and reduces the wear of liner and piston rings.

The piston consists of a piston crown and piston skirt. The piston crown is tightened to the upper end of the piston rod by studs and nuts.
The piston skirt is tightened to the piston crown by means of flanged screws. The piston crown is provided with four grooves for housing the piston rings.
The piston skirt is fitted with two rubbing rings. The piston rod has a bore for cooling oil pipe.
The pipe is secured to the piston rod top by means of flanged screws. The oil from the crosshead flows through the cooling oil pipe to the crown.
The oil after cooling the crown returns to the crosshead and flows out to slotted pipe, which returns back to the sump.
The piston rod is fastened to the crosshead pin by studs and nuts.

Piston rod stuffing box is fitted in the bore for piston rod on a flange which is bolted to the bottom plate of the scavenge air space.
The stuffing box is removed with the piston rod during piston inspection. It can be dismantled for inspection in the crankcase with the piston in place.
The stuffing box housing consists of two parts which are bolted together. The housing is provided with ring grooves.
The top scraper and sealing rings prevent the sludge and scavenge air leaking along the piston rod.
The lower scraper ring scraps the lubricating oil off the piston rod. The scraper and sealing rings are in parts and held in place round the piston rod by helical springs.

Also, check reference: Marine Diesel Engine

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