7.11 Bearings

Question 1

Bearings are used to support what?

Answer 1

Shafts and axles

Question 2

Bearings that accept forces at right angles to the drilling axis are known as what?

Answer 2

Journal or roller bearings

Question 3

What are bearings that accept forces in the longitudinal direction called?

Answer 3

Pivot or axial bearings

Question 4

The journal of a slider bearing operates in what?

Answer 4

Bearing box
Bearing bushing
Or directly in bearing body

Question 5

To decrease friction between the journal and bearing what must you do?

Answer 5

Have sufficient lubrication

Question 6

What does the amount of bearing play depend on?

Answer 6

The demands the bearing is subjected to

Question 7

Characteristics of sliding bearings?

Answer 7

Resist radial loads
Make little to no noise
Suitable for both slow and fast rotational journal speeds

Question 8

Disadvantages of sliding bearings

Answer 8

High starting resistance
Continuous maintenance

Question 9

Five basic types of anti friction bearings?

Answer 9

Tapered roller bearing
Needle bearing
Spherical roller bearing
Ball bearing
Cylindrical roller bearing

Question 10

What does lubricants prevent for bearing?

Answer 10

Prevents heating
Prevents corrosion on bearing surface

Question 11

As a bearing rotates, the mating surfaces create what?

Answer 11

Lubricant film that separates components

Question 12

What happens if you over grease a bearing?

Answer 12

Excess churning will occur
Could generate extremely high temperatures that is a fire hazard

Question 13

Bearings are protected with what in shipping?

Answer 13

A preservative coating but is NOT a lubricant

Question 14

Is the preservative coating on bearings compatible with lubrication?

Answer 14

Yes
It doesn’t need washing off prior to installation

Question 15

What does excessive loads cause?

Answer 15

Premature fatigue

Question 16

What else can cause early fatigue failure in bearings?

Answer 16

Tight fits
Brinelling
Improper preloading

Question 17

What is the solution for bearings with excessive loads?

Answer 17

Reduce the load
Make a bearing with higher weight capacity

Question 18

What are symptoms of overheating in bearings?

Answer 18

Discolouration of the rings
-balls and cages go from gold to blue

Question 19

What can overheating cause for bearings?

Answer 19

Deformation of the balls and rings
Degrades and destroys the lubricant

Question 20

What are common reasons for overheating in bearings?

Answer 20

Heavy electrical loads
Inadequate heat paths
Insufficient cooling or lubrication

Question 21

What does false brinelling of bearings indicate?

Answer 21

Excessive external vibration

Question 22

How do you correct false brinelling?

Answer 22

Isolate bearings from external vibration and using greases containing antiwear additives

Question 23

What is fatigue failure?

Answer 23

Fracture of the running surfaces and subsequent removal of small, discrete particles of material.

Question 24

Where can fatigue failure occur?

Answer 24

Can occur on inner ring
Outer ring
Balls

Question 25

How else can fatigue failure be recognised?

Answer 25

Vibrations that indicates abnormality

Question 26

Angular contact bearings are designed to take what load in how many directions?

Answer 26

Axial loads in one direction

Question 27

Angular contact bearings must be installed in what way?

Answer 27

With resultant thrust on the wide face (It is marked thrust)

Question 28

Symptoms of contamination of bearings?

Answer 28

Denting if the bearings raceways and balls which results in high vibration and wear

Question 29

Some examples of contaminants?

Answer 29

Dust Dirt Abrasive substances

Question 30

What are some sources of contamination?

Answer 30

Dirty tools Contaminated work areas Dirty hands

Question 31

How to reduce chance of contamination?

Answer 31

Clean work areas Tools Hands Keep bearings in correct packaging until ready for application

Question 32

Symptoms of lubricant failure?

Answer 32

Discoloured blue or brown tracks and balls

Question 33

How are lubricant failures usually caused by?

Answer 33

Restricted lubricant flow

Question 34

Symptoms of bearing corrosion

Answer 34

Red/brown colour on balls, cages or bands

Question 35

How to reduce corrosion for bearings?

Answer 35

Divert corrosive fluids away from bearing areas and use integrally sealed bearings where possible

Question 36

What are the most prevalent causes of misalignment?

Answer 36

Bent shafts Burrs or dirt on shaft Shaft threads that aren’t square to shaft seats

Question 37

What indicates a tight fight?

Answer 37

Temperature rise

Question 38

4 general instructions for bearings?

Answer 38

Always use correct tooling Apply correct greases Check bearing block and bearing surfaces for damage Carry out test loading

Question 39

When handling a bearing what should you remember?

Answer 39

Your hands must be clean and dry Surrounding area should be clean

Question 40

How should you store a bearing?

Answer 40

Coat with a preservative Store bearing flat Tightly wrap the bearing in vapour corrosion inhibitor wrapping paper Follow all bearing storage requirements

Question 41

What should the storage area be like for bearings?

Answer 41

Clean Dry Have consistent temperature Free from air flow that would change temperature Humidity less than 75% Free from vibration

Question 42

What is the leading failure of bearings

Answer 42

Contamination

Question 43

What is a symptom of lubricant failure

Answer 43

Discoloured blue/brown ball tracks

Question 44

What is a symptom of corrosion within bearings

Answer 44

Red/brown areas or balls

Question 45

How can misalignment be detected

Answer 45

By a ball wear bath nit being parallel to the raceway edges

Question 46

How can you tell if there is a loose fit

Answer 46

As fretting will cause a generation of fine metal particles which oxidises, leaving a brown colour

Question 47

Why are tight fits accompanied by

Answer 47

High temperatures

Question 48

What is a symptom of overheating

Answer 48

Balls and cages go from gold to blue