Page 152 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

Mobil oil or engine oil (Mobil oil or engine oil) Mobil oil is a light thin oil, which is used in engine, dynamo, air
cleaner, brush etc. parts of motor vehicles.
SAE (Society of Automotive Engineers) uses SAE 30 in cold weather and SAE 140 in hot weather. The SAE
system assigns numbers to identify these experiments based on viscosity.
Like ─ SAE 30, SAE 40, SAE 50 etc.
ii Organic Oils: These oils are obtained from animals, plants and fish etc. These oils are easily broken down
into their constituents by heat and tend to oxidize to a paste at low temperatures, as all organic oils contain
alcohols and fatty acids.
Therefore, it is likely that free amount of acid is present in it. The molecules of castor oil are quite large. So,
it can be used as a lubricant. For use for heavy loads, some amount of mineral oil is added to the organic
oil and this mixture is called compound oil.

iii Synthetic Oils: Because synthetic oils are expensive, they are rarely used. These are of two types:
polakaline glycols and silicon’s. Silicon carbide is converted into silicon and oxygen by suitable chemical
means. Synthetic oils combine with some other ingredients to form silicone lubricants. These oils maintain
their properties for a very long time, so they are used for lubrication of precision tools.
iv Blended Oils: To make mineral lubricants heavier and increase their viscosity, 5 to 20% fatty oils are
added to them. These oils are also called compound oils.
2 Semi-solid Lubricants: - This oil, which does not flow due to its high viscosity, is called a semi-solid lubricant.
thickeners in mineral oil or organic oils to make it; Compounds like calcium, sodium, aluminum, barium, lithium,
strontium, grease etc. are added. Semi-solid lubricants are mainly grease and Vaseline. Grease is mostly
soft and hard type. Soft grease is usually used to lubricate those parts. Parts on which it is impossible for
lubrication oil to stop; Like wheel axle assembly, rear axle, front axle etc. It is also used to lubricate bush
bearings that transmit more power. Conversely, use hard grease with sharp cutting tools; For example, milling
cutters etc. are done to protect them from corrosion for a long time.
3 Solid Lubricants: - Lubrication by grease and oil cannot be successful at very high temperatures and
pressures; Like Power Hammer or Power Jais working in forging shop. Solid lubricants are used at such
places. These solid lubricants are effective in lubrication even at high temperatures. As a solid lubricant, most
of the graphite powder is mixed with grease or oil and is broken down into components. Solid lubricants are
used to control the heat and pressure generated by friction between machine parts. Sometimes soap stone,
talk, wax, mica etc. are used as solid lubricants.
Application
Application of liquid lubricant oil: Liquid lubricants are commonly used in various applications to reduce friction
and wear between moving parts, such as in engines, machinery, and industrial equipment. They’re applied by
pouring, spraying, or using specialized lubrication systems to ensure smooth operation and prolong the lifespan
of mechanical components.
Application of semi-solid lubricant oil: Semi-solid lubricants, like grease, are used in various applications
where traditional liquid lubricants might not be suitable. Common applications include automotive wheel bearings,
chassis components, industrial machinery, and gears. They provide long-lasting lubrication, resist water washout,
and can withstand heavy loads and extreme temperatures.

Application of solid lubricant oil: Solid lubricants are solids applied to friction surfaces to reduce friction and
wear and prevent surface damage. They may be in the form of powders, films or composite materials. They
include substances with layered structures such as molybdenum disulphide and graphite. These solid lubricants
are highly anisotropic, with weak bonding between particular crystal planes or molecules. Their self-lubrication
properties provide low-friction coefficients.
PROPERTIES OF LUBRICANTS
The main properties of lubricants are as follows
i Oiliness: It is the property of the lubricant that a thin surface of the lubricant is maintained between the two
moving parts, due to which the two parts move easily by sliding against each other.

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CITS : Automotive - Mechanic Diesel - Lesson 39 - 46