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IN

INTERNAL COMBUSTION ENGINES

LUBRICATION SYSTEM

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Need for Lubrication

In an I.C. engine, moving parts rub against eachother causing frictional force. Due to the frictional

force, heat is generated and the engine parts

wear easily. Power is also lost due to friction,

since more power is required to drive an enginehaving more friction between rubbing surfaces.

To reduce the power lost and also wear and tear

of the moving part substance called lubricant is

introduced between, the rubbing surfaces.

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Functions of a Lubricant

Lubricant reduces friction between moving part.

It reduces wear and tear of the moving parts.

It minimizes power loss due to friction.

It provides cooling effect. While lubricating it alsocarries some heat from the moving parts and

delivers it to the surroundings through the bottom

of the engine (crank case).

It helps reduce noise created by the movingparts.

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Engine parts to be lubricated

Crank shaft

Crank pin

Big and small end of the connecting rode

Piston pin Internal surfaces of cylinder walls

Piston rings

Valve mechanisms

Cam shaft etc.

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Types of lubrication system

Petrol lubrication system or Mist lubricationsystem.

Wet sump lubrication system.

Dry sump lubrication system.

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PetrolLubricationSystem This system of lubrication is used in scooters and

motor cycles.

About 3% to 6% of lubricating oil is added with

petrol in the petrol tank.

The petrol evaporates when the engine is

working. The lubricating oil is left behind in the

form of mist.

The parts of the engine such as piston cylinderwalls, connecting rod are lubricated by being

wetted with the oil mist.

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TwoStroke I.C Engine

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Disadvantages

If the added oil is less, there will not be sufficientlubrication and even result in seizure of the

engine.

If the added oil is more, it will lead to excess

exhaust smoke and carbon deposits in the

cylinder, exhaust parts and spark plugs.

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Wet sump Lubrication System

Engine Lubrication

Two types of wet sump engine lubrication

systems are used in internal-combustion engines.

They are: Splash system

The pressure-feed system.

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The pressure-feed system, with smallmodifications, is the more popular for more

popular for modern automobile engines.

The splash system is used on most lawnmower and outboard engines.

A wet-sump system is simple, low cost, and light

weight. That's why virtually every production

engine in the world uses wet-sump lubrication.

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Pressurefeed system

In the pressure-feed system, oil is forced by theoil pump through oil lines and drilled

passageways.

The oil, passing through the drilled passageways

under pressure, supplies the necessary

lubrication for the crankshaft main bearings, the

connecting-rod bearings piston-pin bushings,

camshaft bearings, valve lifters, valve push rods,

and rocker studs.

Oil passing through the oil lines is directed to the

timing gears and the valve rocker shafts in order

to lubricate these parts.

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Pressure feed system

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Pressure feed system

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The cylinder walls are lubricated by oil thrown off the

connecting-rod and piston-pin bearings.

Some engines have oil spit holes in the connectingrods that line up with drilled holes in the crankshaft

journal during each revolution, and through or spit a

steam of oil onto the cylinder walls.

Since the oil in the passageways is under pressure,each time the drilled holes in the crankshaft and

connecting rod line up with the holes in the

bearings, the pressure forces the oil through these

drilled passages into the crankshaft and connectingrod, lubricating their respective bearings.

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After the oil has been forced to the area requiring

lubrication, it falls back down into the oil pan readyto be picked up again and returned through the

system.

As the oil falls, it is frequently splashed by the

moving parts onto some other part requiring

lubrication.

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The plash system The splash system is used only on small four-

stroke-cycle engines such as lawn mower

engines.

As the engine is operating, dippers on the ends

of the connecting rods enter the oil supply, pick

up sufficient oil to lubricate the connecting-rod

bearing, and splash oil to the upper parts of the

engine.

The oil is thrown up as droplets, or fine spray,

which lubricates the cylinder walls, piston pins

and valve mechanism.

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Splash system

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Dry Sump Lubrication System

In a wet sump, the oil pump sucks oil from thebottom of the oil pan through a tube, and then

pumps it to the rest of the engine.

In a dry sump, extra oil is stored in a tank

outside the engine rather than in the oil pan.There are at least two oil pumps in a dry sump --

one pulls oil from the sump and sends it to the

tank, and the other takes oil from the tank and

sends it to lubricate the engine. The minimumamount of oil possible remains in the engine.

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Dry sump Lubrication

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A dry-sump system has several advantages overwet, but the main one is additional power.

Because there is only a minimum of oil in the pan,

windageoilclinging to or splashing against the

rotating assemblies of the engine is greatly

reduced.

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In addition to evacuating oil from the pan, the

external oil pump creates a vacuum inside the pan

and block that further increases horsepower byimproving ring seal.

Other advantages of a dry-sump system are

increased oil capacity because of the external tank,

the ability to easily add remote oil coolers, andbecause the pan doesnstoreoil, it can be quite

shallow to allow for lower engine placement.

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Disadvantages

A dry-sump system is More complicated,

More expensive, and

Heavier,

but it offers continuous lubrication under all

conditions and the promise of increased power

through reduced windage.

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QUERIES

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tHANK

YOU!!

-MIHIR