Short Notes: Rolling and Sliding Contact Bearings | Short Notes for Mechanical Engineering PDF Download

 Page 1


Rolling and Sliding Contact Bearings 
Bearing
• A bearing is a mechanical element that permits relative motion between two 
components or parts, such as the shaft and housing, with minimum friction.
Bearing
Rolling contact bearing 
or
Anti-fnction bearing 
or
S im p ly b a ll b e a rin g
• Deep groove ball bearing
- Cylindrical roller bearing 
¦ Angular contact bearing
- Self aligning bearing
- Taper roller bearing
Sliding contact beanng 
or
Plain bearing 
or
Journal bearing 
or
Sleeve beanng
Hydrodynamic 
bearing 
Classification of bearing
Hydrostatic
beanng
• Bearings permit smooth, low-friction movement between two surfaces. The 
movement can be either rotary (a shaft rotating within a mount) or linear (one 
surface moving along another).
• Bearings can employ either a sliding or a rolling action. Bearings based on 
rolling action are called rolling-element bearings. Those based on sliding 
action are called plain bearings.
Sliding Contact Bearings(PLAIN BEARINGS)
Page 2


Rolling and Sliding Contact Bearings 
Bearing
• A bearing is a mechanical element that permits relative motion between two 
components or parts, such as the shaft and housing, with minimum friction.
Bearing
Rolling contact bearing 
or
Anti-fnction bearing 
or
S im p ly b a ll b e a rin g
• Deep groove ball bearing
- Cylindrical roller bearing 
¦ Angular contact bearing
- Self aligning bearing
- Taper roller bearing
Sliding contact beanng 
or
Plain bearing 
or
Journal bearing 
or
Sleeve beanng
Hydrodynamic 
bearing 
Classification of bearing
Hydrostatic
beanng
• Bearings permit smooth, low-friction movement between two surfaces. The 
movement can be either rotary (a shaft rotating within a mount) or linear (one 
surface moving along another).
• Bearings can employ either a sliding or a rolling action. Bearings based on 
rolling action are called rolling-element bearings. Those based on sliding 
action are called plain bearings.
Sliding Contact Bearings(PLAIN BEARINGS)
• A plain bearing is any bearing that works by sliding action, with or without 
lubricant. This group encompasses essentially all types other than rolling- 
element bearings.
• Plain bearings are often referred to as either sleeve bearings or thrust 
bearings, terms that designate whether the bearing is loaded radially or 
axially.
• Lubrication is critical to the operation of plain bearings, so their application 
and function is also often referred to according to the type of lubrication prin­
ciple used. Thus, terms such as hydrodynamic, fluid-film, hydrostatic, 
boundary-lubricated, and self-lubricated are designations for particular types 
of plain bearings.
• Mostly bearings are oil-lubricated. The designs shown in the following figures, 
simple and effective arrangements for providing supplementary lubrication.
Common methods of lubricating plain bearings
• Oil groove in bearing:
• Oil hole in shaft:
Journal or Sleeve Bearings
• These are cylindrical or ring-shaped bearings designed to carry radial loads.
• The terms sleeve and journal are used more or less synonymously since 
sleeve refers to the general configuration while journal pertains to any portion 
of a shaft supported by a bearing.
• In another sense, however, the term journal may be reserved for two-piece 
bearings used to support the journals of an engine crankshaft.
Page 3


Rolling and Sliding Contact Bearings 
Bearing
• A bearing is a mechanical element that permits relative motion between two 
components or parts, such as the shaft and housing, with minimum friction.
Bearing
Rolling contact bearing 
or
Anti-fnction bearing 
or
S im p ly b a ll b e a rin g
• Deep groove ball bearing
- Cylindrical roller bearing 
¦ Angular contact bearing
- Self aligning bearing
- Taper roller bearing
Sliding contact beanng 
or
Plain bearing 
or
Journal bearing 
or
Sleeve beanng
Hydrodynamic 
bearing 
Classification of bearing
Hydrostatic
beanng
• Bearings permit smooth, low-friction movement between two surfaces. The 
movement can be either rotary (a shaft rotating within a mount) or linear (one 
surface moving along another).
• Bearings can employ either a sliding or a rolling action. Bearings based on 
rolling action are called rolling-element bearings. Those based on sliding 
action are called plain bearings.
Sliding Contact Bearings(PLAIN BEARINGS)
• A plain bearing is any bearing that works by sliding action, with or without 
lubricant. This group encompasses essentially all types other than rolling- 
element bearings.
• Plain bearings are often referred to as either sleeve bearings or thrust 
bearings, terms that designate whether the bearing is loaded radially or 
axially.
• Lubrication is critical to the operation of plain bearings, so their application 
and function is also often referred to according to the type of lubrication prin­
ciple used. Thus, terms such as hydrodynamic, fluid-film, hydrostatic, 
boundary-lubricated, and self-lubricated are designations for particular types 
of plain bearings.
• Mostly bearings are oil-lubricated. The designs shown in the following figures, 
simple and effective arrangements for providing supplementary lubrication.
Common methods of lubricating plain bearings
• Oil groove in bearing:
• Oil hole in shaft:
Journal or Sleeve Bearings
• These are cylindrical or ring-shaped bearings designed to carry radial loads.
• The terms sleeve and journal are used more or less synonymously since 
sleeve refers to the general configuration while journal pertains to any portion 
of a shaft supported by a bearing.
• In another sense, however, the term journal may be reserved for two-piece 
bearings used to support the journals of an engine crankshaft.
BEARING HOUSING
• The simplest and most widely used types of sleeve bearings are cast-bronze 
and porous-bronze (powdered-metal) cylindrical bearings.
• Cast-bronze bearings are oil-, or grease-lubricated. Porous bearings are 
impregnated with oil and often have an oil reservoir in the housing.
• Plastic bearings are being used increasingly in place of metal. Originally, 
plastic was used only in small, lightly loaded bearings where cost saving were 
the primary objective.
• More recently, plastics are being used because of functional advantages, 
including resistance to abrasion, and they are being made in large sizes.
Thrust Bearings
• This type of bearing differs from a sleeve bearing in that loads are supported 
axially rather than radially which is shown in the following figure. Thin, disk 
like thrust bearings are called thrust washers.
LQAP
Bearing Materials
• Babbitts
° Tin and lead-base babbitts are among the most widely used bearing 
materials. They have an ability to embed dirt and have excellent 
compatibility properties under boundary-lubrication conditions.
° In bushings for small motors and in automotive engine bearings, babbitt 
is generally used as a thin coating over a steel strip. For larger bearings 
in heavy-duty equipment, thick babbitt is cast on a rigid backing of steel 
or cast iron.
• Bronzes and Copper Alloys
° Dozens of copper alloys are available as bearing materials. Most of 
these can be grouped into four classes: copper-lead, lead-bronze, tin- 
bronze, and aluminum-bronze.
• Aluminum
Page 4


Rolling and Sliding Contact Bearings 
Bearing
• A bearing is a mechanical element that permits relative motion between two 
components or parts, such as the shaft and housing, with minimum friction.
Bearing
Rolling contact bearing 
or
Anti-fnction bearing 
or
S im p ly b a ll b e a rin g
• Deep groove ball bearing
- Cylindrical roller bearing 
¦ Angular contact bearing
- Self aligning bearing
- Taper roller bearing
Sliding contact beanng 
or
Plain bearing 
or
Journal bearing 
or
Sleeve beanng
Hydrodynamic 
bearing 
Classification of bearing
Hydrostatic
beanng
• Bearings permit smooth, low-friction movement between two surfaces. The 
movement can be either rotary (a shaft rotating within a mount) or linear (one 
surface moving along another).
• Bearings can employ either a sliding or a rolling action. Bearings based on 
rolling action are called rolling-element bearings. Those based on sliding 
action are called plain bearings.
Sliding Contact Bearings(PLAIN BEARINGS)
• A plain bearing is any bearing that works by sliding action, with or without 
lubricant. This group encompasses essentially all types other than rolling- 
element bearings.
• Plain bearings are often referred to as either sleeve bearings or thrust 
bearings, terms that designate whether the bearing is loaded radially or 
axially.
• Lubrication is critical to the operation of plain bearings, so their application 
and function is also often referred to according to the type of lubrication prin­
ciple used. Thus, terms such as hydrodynamic, fluid-film, hydrostatic, 
boundary-lubricated, and self-lubricated are designations for particular types 
of plain bearings.
• Mostly bearings are oil-lubricated. The designs shown in the following figures, 
simple and effective arrangements for providing supplementary lubrication.
Common methods of lubricating plain bearings
• Oil groove in bearing:
• Oil hole in shaft:
Journal or Sleeve Bearings
• These are cylindrical or ring-shaped bearings designed to carry radial loads.
• The terms sleeve and journal are used more or less synonymously since 
sleeve refers to the general configuration while journal pertains to any portion 
of a shaft supported by a bearing.
• In another sense, however, the term journal may be reserved for two-piece 
bearings used to support the journals of an engine crankshaft.
BEARING HOUSING
• The simplest and most widely used types of sleeve bearings are cast-bronze 
and porous-bronze (powdered-metal) cylindrical bearings.
• Cast-bronze bearings are oil-, or grease-lubricated. Porous bearings are 
impregnated with oil and often have an oil reservoir in the housing.
• Plastic bearings are being used increasingly in place of metal. Originally, 
plastic was used only in small, lightly loaded bearings where cost saving were 
the primary objective.
• More recently, plastics are being used because of functional advantages, 
including resistance to abrasion, and they are being made in large sizes.
Thrust Bearings
• This type of bearing differs from a sleeve bearing in that loads are supported 
axially rather than radially which is shown in the following figure. Thin, disk 
like thrust bearings are called thrust washers.
LQAP
Bearing Materials
• Babbitts
° Tin and lead-base babbitts are among the most widely used bearing 
materials. They have an ability to embed dirt and have excellent 
compatibility properties under boundary-lubrication conditions.
° In bushings for small motors and in automotive engine bearings, babbitt 
is generally used as a thin coating over a steel strip. For larger bearings 
in heavy-duty equipment, thick babbitt is cast on a rigid backing of steel 
or cast iron.
• Bronzes and Copper Alloys
° Dozens of copper alloys are available as bearing materials. Most of 
these can be grouped into four classes: copper-lead, lead-bronze, tin- 
bronze, and aluminum-bronze.
• Aluminum
° Aluminum bearing alloys have high wear resistance, load-carrying 
capacity, fatigue strength, and thermal conductivity; excellent corrosion 
resistance; and low cost.
o They are used extensively in connecting rods and main bearings in 
internal-combustion engines; in hydraulic gear pumps, in oil-well 
pumping equipment, in roll-neck bearings in steel mills; and in 
reciprocating compressors and aircraft equipment.
• Porous Metals
° Sintered-metal self-lubricating bearings, often called powdered-metal 
bearings, are simple and low in cost. They are widely used in home 
appliances, small motors, machine tools, business machines, and farm 
and construction equipment.
° Common methods used when supplementary lubrication for oil- 
impregnated bearings is needed are shown in the following figure. •
• Plastics
° Many bearings and bushings are being produced in a large variety of 
plastic materials. Many require no lubrication, and the high strength of 
modern plastics lends to a variety of applications.
Rolling Contact Bearing( Anti-friction Bearing)
• Ball, roller, and needle bearings are classified as antifriction bearings since 
friction has been reduced to a minimum. They may be divided into two main 
groups: radial bearings and thrust bearings. Except for special designs, ball 
and roller bearings consist of two rings, a set of rolling elements, and a cage.
• The cage separates the rolling elements and spaces them evenly around the 
periphery (circumference of the circle). The nomenclature of an antifriction 
bearing is given in the following figure.
Page 5


Rolling and Sliding Contact Bearings 
Bearing
• A bearing is a mechanical element that permits relative motion between two 
components or parts, such as the shaft and housing, with minimum friction.
Bearing
Rolling contact bearing 
or
Anti-fnction bearing 
or
S im p ly b a ll b e a rin g
• Deep groove ball bearing
- Cylindrical roller bearing 
¦ Angular contact bearing
- Self aligning bearing
- Taper roller bearing
Sliding contact beanng 
or
Plain bearing 
or
Journal bearing 
or
Sleeve beanng
Hydrodynamic 
bearing 
Classification of bearing
Hydrostatic
beanng
• Bearings permit smooth, low-friction movement between two surfaces. The 
movement can be either rotary (a shaft rotating within a mount) or linear (one 
surface moving along another).
• Bearings can employ either a sliding or a rolling action. Bearings based on 
rolling action are called rolling-element bearings. Those based on sliding 
action are called plain bearings.
Sliding Contact Bearings(PLAIN BEARINGS)
• A plain bearing is any bearing that works by sliding action, with or without 
lubricant. This group encompasses essentially all types other than rolling- 
element bearings.
• Plain bearings are often referred to as either sleeve bearings or thrust 
bearings, terms that designate whether the bearing is loaded radially or 
axially.
• Lubrication is critical to the operation of plain bearings, so their application 
and function is also often referred to according to the type of lubrication prin­
ciple used. Thus, terms such as hydrodynamic, fluid-film, hydrostatic, 
boundary-lubricated, and self-lubricated are designations for particular types 
of plain bearings.
• Mostly bearings are oil-lubricated. The designs shown in the following figures, 
simple and effective arrangements for providing supplementary lubrication.
Common methods of lubricating plain bearings
• Oil groove in bearing:
• Oil hole in shaft:
Journal or Sleeve Bearings
• These are cylindrical or ring-shaped bearings designed to carry radial loads.
• The terms sleeve and journal are used more or less synonymously since 
sleeve refers to the general configuration while journal pertains to any portion 
of a shaft supported by a bearing.
• In another sense, however, the term journal may be reserved for two-piece 
bearings used to support the journals of an engine crankshaft.
BEARING HOUSING
• The simplest and most widely used types of sleeve bearings are cast-bronze 
and porous-bronze (powdered-metal) cylindrical bearings.
• Cast-bronze bearings are oil-, or grease-lubricated. Porous bearings are 
impregnated with oil and often have an oil reservoir in the housing.
• Plastic bearings are being used increasingly in place of metal. Originally, 
plastic was used only in small, lightly loaded bearings where cost saving were 
the primary objective.
• More recently, plastics are being used because of functional advantages, 
including resistance to abrasion, and they are being made in large sizes.
Thrust Bearings
• This type of bearing differs from a sleeve bearing in that loads are supported 
axially rather than radially which is shown in the following figure. Thin, disk 
like thrust bearings are called thrust washers.
LQAP
Bearing Materials
• Babbitts
° Tin and lead-base babbitts are among the most widely used bearing 
materials. They have an ability to embed dirt and have excellent 
compatibility properties under boundary-lubrication conditions.
° In bushings for small motors and in automotive engine bearings, babbitt 
is generally used as a thin coating over a steel strip. For larger bearings 
in heavy-duty equipment, thick babbitt is cast on a rigid backing of steel 
or cast iron.
• Bronzes and Copper Alloys
° Dozens of copper alloys are available as bearing materials. Most of 
these can be grouped into four classes: copper-lead, lead-bronze, tin- 
bronze, and aluminum-bronze.
• Aluminum
° Aluminum bearing alloys have high wear resistance, load-carrying 
capacity, fatigue strength, and thermal conductivity; excellent corrosion 
resistance; and low cost.
o They are used extensively in connecting rods and main bearings in 
internal-combustion engines; in hydraulic gear pumps, in oil-well 
pumping equipment, in roll-neck bearings in steel mills; and in 
reciprocating compressors and aircraft equipment.
• Porous Metals
° Sintered-metal self-lubricating bearings, often called powdered-metal 
bearings, are simple and low in cost. They are widely used in home 
appliances, small motors, machine tools, business machines, and farm 
and construction equipment.
° Common methods used when supplementary lubrication for oil- 
impregnated bearings is needed are shown in the following figure. •
• Plastics
° Many bearings and bushings are being produced in a large variety of 
plastic materials. Many require no lubrication, and the high strength of 
modern plastics lends to a variety of applications.
Rolling Contact Bearing( Anti-friction Bearing)
• Ball, roller, and needle bearings are classified as antifriction bearings since 
friction has been reduced to a minimum. They may be divided into two main 
groups: radial bearings and thrust bearings. Except for special designs, ball 
and roller bearings consist of two rings, a set of rolling elements, and a cage.
• The cage separates the rolling elements and spaces them evenly around the 
periphery (circumference of the circle). The nomenclature of an antifriction 
bearing is given in the following figure.
BEARING LOADS 
• Radial Load
° Loads acting perpendicular to the axis of the bearing are called radial 
loads. Although radial bearings are designed primarily for straight radial 
service, they will withstand considerable thrust loads when deep ball 
tracks in the raceway are used.
LOAD
C
I ' / / t P / A
i - ^ - 4
4
L O A D
(A ) R A D I A L
• Thrust Load
o Loads applied parallel to the axis of the bearing are called thrust loads. 
Thrust bearings are not designed to carry radial loads.
(B) THRUST