Lubrication reduces wear on surfaces in contact by reducing friction. Lubricants typically contain 90% base oil and less than 10% additives. Non-liquid lubricants like grease are used at higher temperatures up to 350°C. Lubrication systems include wet and dry sump, splash and forced feed methods. Wet sump splash systems are common and inexpensive, while dry sump and forced feed systems are used for larger engines. Lubricants must have properties like viscosity, stability, and thermal stability to properly lubricate engine parts like bearings and reduce wear.

1. BY SUJOY SAHA

2. Lubrication
Lubrication is the process, or technique employed
to reduce wear on surfaces in close proximity, and
moving relative to each another.
Lubricants

3. Composition of lubricants
Typically contains 90% base oil (petroleum-mineral oils)
and less than 10% additives
Non liquid lubricants contains Grease, powder(dry
graphite, Molibdenum disulphite), Teflon tape used in
plumbing etc.
Those non liquid lubricants provide lubrication at higher
temp.(up to 350 °C)
Additives
The properties of a lubricant can be improved by adding

4. Objectives of Lubrication
To reduce frictional resistance.
To reduce wear on the bearing surfaces.
To protect the bearing surfaces from
corrosion.
To carry away heat from the bearing.
To reduce noise from the moving
components of the machine.

5. Lubricating Methods
A.Petroil/ mist lubrications system
B.Dry sump lubrication system
C.Wet sump lubrication system -
a)Splash lubrications system
b)Forced/ pressurized feed

6. Petroil/ mist lubrications system
In this type of system, a certain amount of oil is
mixed with petrol itself. Therefore 3 to 6% of oil
mixed with fuel. This proportion should be proper. If
this proportion is less, the danger of oil starvation
causes damage to the engine.
If this proportion is more, the engine gives dark
smoke and excessive carbon deposits on the
cylinder head.

7. Dry Sump lubrication method
This system consists of two
pumps.One scavenging pump placed
below the sump, other pressure pump
placed at the tank.
Scavenging pumps supply lubricating
oil to the main tank through the filter
and, pressure pump supplies oil to the
different parts of an engine through
the oil cooler.
In this system, the pressure of oil is
about 4 to 5 kg/cm2.
Here sump is kept dry. Hence called a
Dry sump lubrication system.
This type of system is used in the
sports car, and certain military
vehicles extra.

8. Splash lubrication system
This is the most popular type
of
lubrication system duly used
in cars
extra.This is one of the
cheapest methods of the
lubrication system.
It consists of a scoop, which
is fitted at the lower end of
the connecting rod as shown

9. Pressure/Force Feed method
This system is used because the splash
system is not sufficient for larger engines
like Ambassdor, jeep and others.
Oil from the sump will be supplied to the
engine parts through main reservoir via
strainer, filter and pump.
the pressure of oil is about 2 to 4 kg/cm2.
for camshaft and timing gears., oil is
supplied by a seperate line through the
pressure reducing valves.
This type of system , oil pressurized by
using gear pump.

10. Types of Lubricant
Animal oils - From animal fats
Vegetable oils - From plant seeds
Mineral oils - Hydrocarbons obtained from minerals
Synthetic oils -From various chemicals
Grease - Semi-fluid lubricant
Synthetic lubricants - Polyglycols,Silicones
Dry - Molybdenum disulphide, Graphite
Solid lubricants - Wax , Talc, Mica, Molibdenum disulphide
Semi solid lubricants - Grease and Vaseline
Liquid Lubricants - Mineral oils , Vegetable oils, Animal oils

11. Properties of Lubricant
 Viscosity - Resistance of a liquid to flow.
 Oiliness - Ability of the lubricant to stay in place between the bearing
surfaces.
 Stability - Retention of properties as long as possible. (Oxidization)
 Volatility - It shows the evaporation behavior of lubricant at high
temperature.A good lubricant should have low volatility.
 Emulsification - It is the property of a lubricant due to which the
lubricating oil mixed with water to form an emulsion.A good lubricant
should have low emulsion number.
 Corrosion Stability - It is properties of lubricant which represents its
resistance toward the metals.A good lubricant should not take part in
corrosion.
 Thermal Stability - A good lubricant must be stable towards heat.It

12. Functions of Lubricants
Keep moving parts apart
Reduce friction
Transfer heat
Carry away contaminants & debris
Transmit power
Protect against wear
Prevent corrosion

13. Parts of Lubricating system
•Oil sump
•Oil pump
•Oil cooler
•Oil filter and strainer
•Oil pressure gauge
•Oil pressure indicating light
•Oil level indicator

14. Lubricating Parts of Engine
•Main crankshaft bearings
•Big end bearings
•Small end bearings
•Camshaft bearings
•Piston rings and cylinder walls
•Timing gears
•Valve mechanisms