CROSSHEAD BEARING HAS AN OSCILLATING MOTION AND LOWER PART IS ALWAYS LOADED. HENCE IT IS NOT EASY TO LUBRICATE THIS BEARING. M.A.N B&W ENGINES INJECTS L.O TO CRANKCASE AT ABOUT 2.5 BAR PRESSURE WHILE SULZER USES AN ADDITIONAL PUMP TO INCREASE THE PRESSURE TO CROSSHEAD TO ABOUT 14 BAR. BUT THE QUESTION COMES IS WHY DID SULZER ENGINE HAVE SUCH A HIGH PRESSURE.
THE ANSWER LIES IN THE DESIGN OF THE BEARING IN THE TWO ENGINES.
NOW IF WE LOOK CLOSELY, THE CROSSHEAD BEARING OF M.A.N B&W CONSIST OF OIL GROOVES IN THE LOWER BEARING. THIS SPECIAL GROOVES PREVENT OIL SCRAPING EFFECT AND ENHANCE THE HYDRODYNAMIC BUILD UP OF LOAD CARRYING OIL FILM TOWARDS THE LOADED AREA OF THE BEARING WHILE THAT OF THE SULZER DO NOT HAVE THOSE OIL GROOVES TO RETAIN THE OIL FILM AND HENCE REQUIRE A GREATER PRESSURE TO INJECT THE OIL BETWEEN THE PIN AND THE BEARING.
4 responses to “WHY CROSSHEAD BEARING PRESSURE OF M.A.N B&W IS MUCH LOWER THAN THAT OF SULZER”
So why does not Sulzer do the same thing?
I didn’t get u. What do sulzer do?
In M.A.N. B&W the crosshead lubricantion is hydraudynamic lubrication.
And in SULZER the crosshead lubricantion is hydraustatic lubrication .
That’s why the SULZER require an additional pump to create the required pressure for lubrication.
The mai reason is that in case of MAN B&W crosshead lower shell bearings have different modification than sulzer crosshead bearing in the b&w lower shell have grooves and passage for lube oil to get more thik oil film generates for load carrying capacity improve ,