This is the basic information about bearing, this includes bearing type, selection of bearing depending on exerting loads by the machine on bearings and lubrication method of bearing.

1. Back to basic:Rolling Bearings
Bearing is a rolling machine element. It keeps our machine parts in motion all the time. Our machines
can not move without the use of bearings. Bearing is an essential element for our machine. Toys to
spacecraft are installed with bearings. Function of bearing is to reduce the friction between moving
parts of a machine. Reduction in the friction between machine parts smooth ens the movement and
increases the efficiency of the machine.
Machine exerts various kind of loads on machine parts while in motion. These loads may be in the
radial direction or in axial direction. Bearings absorb the radial and axial loads of the machine and
makes the machine movement easy. Depending on the kind of load exerting in the machine, type of
bearing is selected and installed.
There are many bearings that can withstand both radial and axial loads.
TYPE OF BEARINGS:
Depending on the type of rolling element bearings are classified in two main categories:
(1) Ball bearings
(2) Roller bearings
BALL BEARINGS
Ball bearing is consists of parts:
(1) Outer ring
(2) Inner ring
(3) Ball
(4) Cage or Separator
Depending on design, ball bearings are further categorized as follows:
(1) Single row deep groove ball bearing
(2) Double row deep groove ball bearing
(3) Single row angular contact ball bearing
(4) Double row angular contact ball bearing
(5)Three point/ Four point contact ball bearings
(6)Self aligning ball bearing
ROLLER BEARING
Roller bearing is consists of parts:
(1) Outer ring
(2) Inner ring
(3) Roller
(4) Cage or Separator
Depending on design, roller bearings are further categorized as follows:
(1) Single row Cylindrical roller bearing
(2) Double row Cylindrical roller baring
(3) Long roller bearing
(4) needle roller bearing
(5) Single row Tapered roller bearing
(6) Double row Taper roller bearing
(7) Spherical roller bearing

2. BEARING USES:
Ball bearings
Ball bearings are common in use. They are found in many machines from skate boards to washing
machine and PC drives. These bearings are capable to withstand both radial and axial thrust loads.
They are used in applications where load is light to medium and constant in nature.
BALL THRUST BEARING
Ball thrust bearings are used in low speed applications. They can not take much radial loads however
suitable for thrust loads. They are used in turntable and farm equipment's.
ROLLER BEARINGS
Roller bearings are used for heavy load applications like conveyor belt rollers where heavy radial loads
exists. In these bearings the rolling element is the cylindrical roller, hence there is the line contact
between outer race, inner race and roller. This line contact distributes the load over a large area, so
the roller bearings handle much greater load than ball bearing.
ROLLER THRUST BEARINGS
Roller thrust bearings can withstand very heavy thrust loads. They are used in car gear transmission,
Power transmission between gear and sprockets, Helical gear power transmission that causes heavy
thrust loads, can be supported by roller thrust bearings.
TAPERED ROLLER BEARINGS
Tapered roller bearings are designed to withstand heavy radial and thrust loads. They are capable to
withstand constant and impact loads.
ANGULAR CONTACT BALL BEARING
Angular contact ball bearings are constructed in such a way that their inner race, outer race and ball
are in contact at some angle. Standard contact angles are 15,30 and 40 degree. Preloading is done in
angular contact bearings during bearing assembly. Preloading minimizes the gap between the bearing
ball, inner race and outer race. They are used for heavy thrust loads and moderate radial loads.
SELECTION OF BEARING TYPE
Bearing are of many types and design. Bearing selection to be done in such a way, that it enable
machine or part to perform their work satisfactorily. Following factors to be considered when
selecting a bearing.
(1) Machine Type, space available for bearing installation.
(2) Bearing operating condition, continuous or intermit ant
(3) Weather condition of the area
(4) Bearing location
(5) Bearing load, direction and magnitude
(6) Bearing vibration and impact load
(7) Bearing temperature
(8) Machine shaft size
(9) Bearing inner diameter
(10)Bearing outer diameter
(11)Bearing overall dimensions
(12) Bearing rolling element, depending on load

3. (13) Bearing lubrication, oil or grease
BEARING LUBRICATION
Bearing lubrication reduces the friction between the rolling parts. The purpose of bearing lubrication
is to prevent direct metallic contact between the various parts of bearing. A thin layer of oil or grease
is formed on the contact surface to accomplish the purpose. Lubrication has other advantages:
(1) Reduce friction
(2) Reduce wear and tear
(3) Heat dissipation
(4) Prolonged bearing life
(5) Prevent rust
(6)Prevent water and dust ingression in the bearing.
Bearing lubrication are of two type
(1) Oil lubrication
(2) Grease lubrication
OIL LUBRICATION
Oil lubrication is most suitable for high speed and high temperature application. Oil lubrication can
dissipate heat generated by bearing very effectively. Spindle oil, machine oil, turbine oil and other
mineral oil are used as lubricant in normal operating condition. For temp. Above 150 degree
centigrade, synthetic oil such as silicone and flurosilicone are used.
Viscosity of oil determines the oil lubrication application. If viscosity is too low, the oil film will not be
formed and if viscosity too high, create the viscosity resistance and causes the bearing temperature
rise.
For higher speed, a low viscosity oil to be used and for heavy loads higher viscosity oil to be used
METHOD OF LUBRICATION
OIL BATH
Oil bath lubrication is used for horizontal shaft application. Oil level in the bath to be maintained at
the centre of the lowest rolling element of bearing. Housing design should be such that oil level does
not fluctuate.
OIL SPLASH
In splash oil lubrication an impeller like device to be mounted on the shaft to pick up the oil and spray
it on the bearing. This is used for high speed application. Drip lubrication is used for high speed and
light to medium load application. Constant oiler is mounted on the housing above the bearing and
allow oil to drip in the bearing.
GREASE LUBRICATION
Grease lubrication of bearing is easier than the oil lubrication. Because of viscosity grease lubrication is
long-lasting and requires simple sealing. New grease is pumped through grease nipple that replaces
the old grease from the equipment bearing. Grease are composed of mineral oil base and synthetic oil
base like silicone oil and fluorocarbon oil mixed with thickener. The base oil determines the properties
of the grease.

4. Grease with low viscosity base oil are best suited for low temperature and high speed, while grease
made from high viscosity base oil are suited for heavy load application