Wet sump lubrication system:
Bottom of the crankcase contains oil pan or sump from which the lubricating oil is pumped to various engine components by a pump. After lubrication, oil flows back to the sump by gravity. Three types of wet sump lubrication system,
(i) Splash system
(ii) Splash and pressure system
(iii) Pressure feed system
(i) Splash system:
-In this system of lubrication the lubricating oil is stored in an oil sump. A scoop or dipper is made in the lower part of the connecting rod. When the engine runs, the dipper dips in the oil once in every revolution of the crank shaft, the oil is splashed on the cylinder wall. Due to this action engine walls, piston ring, crank shaft bearings are lubricated.
-It is used for light duty engine
Fig. 40. Splash lubricating system
(ii) Splash and pressure system:
Lubricating oil is supplied under pressure to main, camshaft bearings and pipes which direct a stream of oil against the dippers on the big end of connecting rod bearing cup and thus crankpin bearings are lubricated by the splash or spray of oil thrown up by the dipper.
Fig. 41. Splash and pressure lubricating system
(iii) Pressure feed system:
In this system of lubrication, the engine parts are lubricated under pressure feed. The lubricating oil is stored in a separate tank (in case of dry sump system) or in the sump (in case of wet sump system), from where an oil pump (gear pump) delivers the oil to the main oil gallery at a pressure of 2-4 kg/cm2 through an oil filter. The oil from the main gallery goes to main bearing, from where some of it falls back to the sump after lubricating the main bearing and some is splashed to lubricate the cylinder walls and remaining goes through a hole to the
crank pin. From the crank pin the lubricating oil goes to the piston pin through a hole in the connecting rod, where it lubricates the piston rings. For lubricating cam shaft and gears the oil is led through a separate oil line from the oil gallery. The oil pressure gauge used in the system indicates the oil pressure in the system. Oil filter & strainer in the system clear off the
oil from dust, metal particles and other harmful particles.
Fig. 42. Pressure lubricating system
Gear system:
-Used for a medium sized diesel engine
-It is a forced-feed system of lubrication and uses the oil contained in the bed plate as a reservoir. A gear type oil pump is driven from the crankshaft.
-The oil enters the pump and is carried around the pump casing by the gear teeth. It is then discharged. The oil is prevented from returning to the inlet by the meshing of the gear teeth. Oil is pumped from the bed plate through an oil filter and cooler into the lubricating oil manifold. A separate pipe supplies oil to the turbocharger. A supply of cooled oil is critical for the turbocharger to lubricate the high-speed bearings and to carry heat away from the rotor.
Fig. 43. Gear type lubrication system
(c) Dry sump lubrication system:
-Supply of oil is carried in external tank
-Oil pump draws oil from the supply tank and circulates it under pressure to various bearings of the engine
- Oil dripping from the cylinders and bearings into the sump is removed by a scavenging pump and again return to supply tank through the filter
-The capacity of scavenging pump is greater than the oil pump
-Separate oil cooler to remove heat from oil is used which is either cooled by air or water
Bottom of the crankcase contains oil pan or sump from which the lubricating oil is pumped to various engine components by a pump. After lubrication, oil flows back to the sump by gravity. Three types of wet sump lubrication system,
(i) Splash system
(ii) Splash and pressure system
(iii) Pressure feed system
(i) Splash system:
-In this system of lubrication the lubricating oil is stored in an oil sump. A scoop or dipper is made in the lower part of the connecting rod. When the engine runs, the dipper dips in the oil once in every revolution of the crank shaft, the oil is splashed on the cylinder wall. Due to this action engine walls, piston ring, crank shaft bearings are lubricated.
-It is used for light duty engine
Fig. 40. Splash lubricating system
(ii) Splash and pressure system:
Lubricating oil is supplied under pressure to main, camshaft bearings and pipes which direct a stream of oil against the dippers on the big end of connecting rod bearing cup and thus crankpin bearings are lubricated by the splash or spray of oil thrown up by the dipper.
Fig. 41. Splash and pressure lubricating system
(iii) Pressure feed system:
In this system of lubrication, the engine parts are lubricated under pressure feed. The lubricating oil is stored in a separate tank (in case of dry sump system) or in the sump (in case of wet sump system), from where an oil pump (gear pump) delivers the oil to the main oil gallery at a pressure of 2-4 kg/cm2 through an oil filter. The oil from the main gallery goes to main bearing, from where some of it falls back to the sump after lubricating the main bearing and some is splashed to lubricate the cylinder walls and remaining goes through a hole to the
crank pin. From the crank pin the lubricating oil goes to the piston pin through a hole in the connecting rod, where it lubricates the piston rings. For lubricating cam shaft and gears the oil is led through a separate oil line from the oil gallery. The oil pressure gauge used in the system indicates the oil pressure in the system. Oil filter & strainer in the system clear off the
oil from dust, metal particles and other harmful particles.
Fig. 42. Pressure lubricating system
Gear system:
-Used for a medium sized diesel engine
-It is a forced-feed system of lubrication and uses the oil contained in the bed plate as a reservoir. A gear type oil pump is driven from the crankshaft.
-The oil enters the pump and is carried around the pump casing by the gear teeth. It is then discharged. The oil is prevented from returning to the inlet by the meshing of the gear teeth. Oil is pumped from the bed plate through an oil filter and cooler into the lubricating oil manifold. A separate pipe supplies oil to the turbocharger. A supply of cooled oil is critical for the turbocharger to lubricate the high-speed bearings and to carry heat away from the rotor.
Fig. 43. Gear type lubrication system
(c) Dry sump lubrication system:
-Supply of oil is carried in external tank
-Oil pump draws oil from the supply tank and circulates it under pressure to various bearings of the engine
- Oil dripping from the cylinders and bearings into the sump is removed by a scavenging pump and again return to supply tank through the filter
-The capacity of scavenging pump is greater than the oil pump
-Separate oil cooler to remove heat from oil is used which is either cooled by air or water
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