Q. What Are The Functions Of Main Engine Lubricating Oil System?
Ans: Lubricating Oil Is Used For Lubrication Of The Running Gear Consisting Of Crank Shaft Bearings, Bottom End Bearings, Top End Bearings, Thrust Bearing, Cross Head Guides, Chains, Cams, And Gears Within The Crankcase. In Modern Engines, Oil Supply To Crosshead Bearing Is Arranged With Pressure Boosing Device To Achieve Higher Pressure To Force The Oil Between The Bearing And The Cross Head Pin At Peak Loads.
Basic Functions Of Lubricating Oil Are: Reducing Friction Between Moving Parts In Contact, Cooling, Cleaning, And Protecting Components Against Corrosion.
Q. Explain The Diesel Engine Lub. Oil System?
Ans: Line Diagram For Diesel Engine Lub Oil System 
Here In The Diagram Above, We Can See
i) Sump Tank: Sump Tank Is A Lub Oil Collection Tank At The Bottom Of The Diesel Engine, Where The System Oil Returns And Get Collected After Lubricating The Parts. Again, This System Oil Is Transferred Back Into The System By Pumps.
ii) Centrifugal Separator: Its Also Known As Auto Backwash Filter, It Takes Up The Lub Oil From Sump And Passes It Through A Revolving Filter Mesh.Thus, Cleaning The Oil For Reuse.
iii) Strainer: It’s A Filter Which Separates Bigger And Heavier Objects And Does Not Allow Them To Move Into The Pump, Thereby Helping Them Not To Clog The Sytem. These Objects Like Cloth Or Spanner Might Be Lying Into The Sump, Which May Have Fallen During Inspection.
iv) Pumps: These Are Two In Number, One In Use And Other Standby. If They Are Submerged In The Sump, They Will Be Centrifugal Pumps Otherwise They Will Be Screw Pumps. Centrifugals Are Submerged Into The Sump Because It Helps To Maintain Constant Suction And Theier Is No Fear Of Loosing Suction. Generally, The Pressure Is Maintained At 4-4.5 Bar In MAN B&W Engines.
v) Fine Filter: It Separates The Small Particles Such As Metal Particles To Enter Into The System.
vi) Cooler: Generally Plate Type Heat Exchangers Are Used For The Purpose. They Have Better Cooling Efficiency Than Tube Type Coolers. Lub Oil Is Cooled Upto 40-45 Deg C. Reason For Cooling Is That Oil Gets Heated Up Due To Contact With With Heating Parts, While Cooling Them.
Q. What Are The Functions Of M/E Cylinder Lubrication System?
Ans: Cylinder Oil Reduces Frictional Resistance Between Piston Rings And Liners, Neutralises Acidic Conditions Created By The Products Of Combustions, And Act As An Insulting Film Between Cylinder Wall And Hot Gases. Here Is A Line Diagram For Cylinder Lub Oil System. From The Diagram Its Clear How The System Is Functioning.
Q. What Is The Function Of A Cam Shaft?
Ans: Function Of The Camshaft Is To Operate Fuel Pumps, Exhaust Valves, And It May Operate Pilot Air Valves For Starting The Engine. On Some Engines, In Some Engines To Prevent Contamination Of Crankcase Oil With Fuel Leaking Past Fuel Pumps, Camshaft Lubrication System Is Independent Of Crankcase Lubrication.
Q. How Does Gear & Turbocharger Lubrication Take Place?
Ans: Gear Lubrication : On Ships With Gears For Propeller Drive, Shaft Generators, Turbo-generators, Etc., A Separate Lubricating Oil System Is Provided.Gear Drive Within The Crankcase Of An Engine Is Lubricated Through The System For Lubrication Of Bearings And Cross-head Guides.
Turbo-charger Bearing Lubrication
Lubrication Of Turbocharger Bearings Is By Means Of Self Driven Pumps And Oil Sumps At Each End Of The Rotor Shaft. On Some Ships, Turbo-charger Bearings Get Supply From The Crankcase Lubricating Oil System Through An Overhead Tank.