Understanding IC Engine Lubrication Systems

Internal Combustion (IC) engines in automobiles have many moving parts that rub against each other. Lubrication is essential to reduce friction, prevent wear, cool the parts, seal clearances, and clean away debris. Several lubrication systems exist, but modern automobile IC engines primarily use a specific type.

Common Lubrication Systems in Automobile Engines

Let's look at some lubrication methods:

• Splash Lubrication: This is an older method where parts like the connecting rod scoop oil from the sump and splash it onto the cylinder walls and other moving parts. It's simple but doesn't provide consistent lubrication to all critical areas, especially under varying speeds and loads.
• Gravity Lubrication: In this system, oil flows from an oil tank located at a higher level and is distributed to different points by gravity. This method is very basic and not suitable for the complex lubrication needs of a modern, high-speed automobile engine.
• Pressure Lubrication: This is the most advanced and commonly used system in modern automobile IC engines. It uses an oil pump, typically driven by the crankshaft, to force lubricating oil under pressure through passages (drilled holes) in the crankshaft, connecting rods, cylinder block, and cylinder head. This ensures that oil reaches all critical bearings and moving parts with a consistent supply, regardless of engine speed or orientation (within limits).
• Petrol Lubrication: This is not a type of lubrication system. Petrol is the fuel used in many IC engines. Lubrication is handled by a separate system, usually involving engine oil. Some two-stroke engines use a system where oil is mixed with the petrol (petrol-oil mixture), but this is different from the primary lubrication system of most automobile (typically four-stroke) engines which use a dedicated oil supply and pump.

Why Pressure Lubrication is Common

The pressure lubrication system is preferred in modern automobile IC engines because:

• It provides a continuous and controlled supply of oil to all critical components like main bearings, connecting rod bearings, camshaft bearings, piston pins, cylinder walls, etc.
• The oil pressure helps in creating a hydrodynamic film between moving surfaces, effectively reducing metal-to-metal contact and wear.
• It facilitates efficient cooling by circulating oil through the engine.
• It helps in cleaning by carrying away wear particles and contaminants to the oil filter.
• It is reliable across a wide range of engine operating conditions (speed, temperature, load).

Due to these advantages, the pressure lubrication system is the standard method used in the vast majority of automobile IC engines today.