Bearing & Piston Lubrication [Video Lesson]

The main or crankcase lubrication system is supplied by one of two pumps, one of which will be operating and the other is on standby, set for automatic cut-in should there be a lubricating oil pressure reduction or primary pump failure.

The main LO pumps take their suction from the main engine sump tank and discharge oil via the main LO cooler, which takes away the heat. An automatic backflushing filter unit with a magnetic core helps to remove any metal debris. The plate-type LO cooler is cooled from the low-temperature central cooling freshwater system.

The supply pressure in the main lubrication system depends on the design and requirement and is generally around 4.5 kg/cm2. LO supply to the cooler is via a three-way valve which enables some oil to bypass the cooler.

The three-way valve maintains a temperature of 45°C at the lubricating oil inlet to the engine. The main LO system supplies oil to the main bearings, camshaft, and camshaft drive. 

A branch of lube oil goes to an articulated arm or a telescopic pipe to the crosshead from where it does three functions

1) some oil travels up the piston rod to cool the piston and then comes down,

2) some oil lubricates the crosshead bearing and the shoe guides

3) the remaining oil passes through a hole drilled in the rod connecting to the bottom end bearing.

A branch of lube oil is led to the hydraulic power supply unit for the actuation of exhaust valves, to the thrust bearings, to the moment compensator, and to the torsional vibration damper. The cooling effect of the oil at the vibration dampers is important.

Watch this video lesson on how lubrication works on these parts –