Power needs to be transmitted from where it is generated to where it is used. Bearings are components that support rotating or moving parts and reduce friction. They come in plain and rolling element types, with the most common being journal bearings that support a rotating shaft using lubrication between surfaces. Gear trains use successively engaging teeth to transmit rotational motion between parts of a mechanical system. Belt, rope, and chain drives are also used to transfer power between rotating shafts.

1. Power and Need of Power Transmission
•Power is the rate at which work is done, i.e.
the rate at which energy is transferred by a
force.
•Units are: HP, kW, J/s
•Need: Power may be transmitted from
where it is generated to the point where it is
used.

2. Bearings
• A bearing is a housing or support for a rotating part or
one that moves linearly.
• Bearings are of two basic types: plain and rolling-
element.
• Plain bearings are based on sliding motion between a
stationary and a moving member, and are almost
universally used in engines.
• Rolling-element bearings have either balls or rollers
that accommodate motion between the stationary and
moving parts.
• A film of lubricant separating moving surfaces is
essential for long service life.

3. Journal Bearings
A journal or sleeve
bearing consists of a
cylindrical housing
supporting a rotating
shaft. The term
"journal" refers to the
portion of a shaft
contained within a
bearing; "sleeve" refers
to the bearing
configuration.

4. Thrust bearing
Thrust bearings accommodate the axial movement of a rotating
shaft. They are usually used in conjunction with journal bearings
and are lubricated by grease, which leaks from the ends of the
journal housings

5. Roller Bearings

6. Ball bearings
• The purpose of a ball bearing
is to reduce rotational friction
and support radial and axial
loads.
• This is point contact bearing.

7. Cylindrical Roller Bearing
• This is line contact
bearing.
• Used for heavy radial
loads.

8. Concept of Gear and Gear trains
• Gears are machine elements that transmit motion by
means of successively engaging teeth.

9. Gears Meshing

10. Gear Trains

11. Gear Trains
• A gear train is a set or
system of gears
arranged to transfer
rotational torque from
one part of a
mechanical system to
another.

12. Belt drives
A belt is a loop of flexible material used to mechanically
link two or more rotating shafts. Belts may be used as a
source of motion, to transmit power efficiently, or to
track relative movement

13. Application of Rope Drive

14. Chain Drive
Chain drive is a way of transmitting mechanical power from one
place to another. It is often used to convey power to the wheels
of a vehicle, particularly bicycles and motorcycles.