Bearings

Question 1

What is a bearing

Answer 1

Bearings consist of load-carrying cylindrical inserts made of hard wearing materials, such as cast iron, phosphor-bronze, white metal or special plastics.
Bearings are used to support the journals of shafts and axles.

Question 2

Plain bearings

Answer 2

Designed for light loads
Frequently require maintenance
Support journals of shafts and axis (journal and roller bearings)

Question 3

Sliding bearings

Answer 3

Operates in bearing box
Bearing brushes directly on the bearing body
For large diameter journals
Lubrication film required
Resistant to push forces
Suitable for both slow and fast rotational speeds

Question 4

Anti friction bearings

Answer 4

Ball bearings have slow start resistance but roller bearings can take higher loads

Question 5

Ball bearings

Answer 5

All types have a point contact

Suitable for light rotation loads

Question 6

Cylindrical roller bearing

Answer 6

Allows axial to accommodate thermal expansion
Line contact rather than point, allow for more load
Heavier cage, fewer rollers, lower load capacity

Question 7

Needle bearing

Answer 7

Long thin rollers
High radial load capacity
Very light axial load capacity

Question 8

Spherical roller bearing

Answer 8

Self-aligning allowing for minor angular displacement
High radial load capacity
Robust cage
Operates where lower speeds are not required

Question 9

Tapered roller bearing

Answer 9

Combines the benefits of the other bearings along with - 
Combined radial and thrust load 
Longer life 
Adjustable either end 
High speeds
Low price for long use 
Low friction coefficient

Question 10

Bearing materials

Answer 10

Copper tin alloy
Copper tin zinc casting alloys
Lead tin alloy
Cast iron

Dry powder metals - contain lube
Good lube = longer life

Question 11

Air bearing

Answer 11

Use a thin film of pressurised air to provide a 0 friction interference
Avoid traditional bearing problems such as friction