The main engine piston is cooled by one of the two cooling mediums- oil or water.
Water-cooled pistons were mainly used in old MAN engines and Sulzer RND, RLA ,RLB engines.
Nowadays, both MAN and Sulzer engines prefer oil cooling to conventional water cooling piston as the former reduces the risk of lube oil contamination in case of leakage.
Here, we will discuss about Difference in lubrication and cooling of piston via oil in sulzer and B & W for oil cooled Engines.
1.In Sulzer engines,Articulate lever is used for lubrication and cooling.
In B & W engines,Telescopic pipe is used for lubrication and cooling.
2.In sulzer engines,External booster pump is used for lubrication of crosshead.There is two pump used for lubrication and cooling 1.Main lube oil pump and 2. Cross head pump.
Crosshead pump is used for crosshead lubrication and bottom end bearings and main lube oil pump for main bearings and one branch go for piston cooling via articulate lever.
There is two articulate lever.One articulate lever supply lube oil for cooling of piston through annular space whose connection is from main lube oil pump.
The other articulate pump which supply lube oil to crosshead for lubrication of crosshead and bottom end bearings whose connection supply from booster pump.
In B & W , there is no requirements of external booster pump. Main lube oil pump supply lube oil to main bearings and after that one branch go to crosshead through telescopic pipe where it branches into 3 sections.
A. For crosshead bearings B. Bottom end bearings and C. For piston cooling through annular space in piston rod.