7.11: Bearings

Question 1

What should be done if there is damage to the shield/seal?

Answer 1

Damage shield/seal. Reject Bearing

Question 2

How are sealed bearings inspected?

Answer 2

Sealed bearings are inspected by rotating slowly by hand

Question 3

How might False Brinelling occur and what might cause it?

Answer 3

False Brinelling
Inspection can be caused by incorrect transport
Occurs through vibration, not necessarily excessive load

Question 4

How is an axial clearance check performed?

Answer 4

Axial clearance check. Outer race is clamped in a jig

Question 5

On what surface does spalling occur?

Answer 5

Spalling appears on the load carrying surface

Remember: Spalling is the break away of the race due to foreign debris/objects getting in
Spalling - ALLING - ALL - Chips broke away ALL over floor

Question 6

What does true brinelling indicate?

Answer 6

True brinelling indicates skidding under high load

Question 7

What colour does selica gel turn when it absorbs moisture?

Answer 7

When selica gel absorbs moisture, it turns pink

Question 8

How is a radial clearance checked?

Answer 8

Radial clearance check. Inner race is clamped in a jig

Radial clearnace check = Inner race clamped (i is easy to make into an r)
axial clearance check = outer race clamped (a similar to o in writing)

Question 9

What can cause Brinelling of a wheel bearing?

Answer 9

Brinelling of a wheel bearing can be caused by a heavy landing

Brinelling - B for Brinelling - B for Ball indented on race

Question 10

What do small indentations in a race of a ball bearing indicate?

Answer 10

Small indentations in a race of a ball bearing indicate Brinelling

Question 11

What does chipping of a ball bearing indicate?

Answer 11

Chipping of a ball bearing indicates spalling

Question 12

What is used to lubricate bearings subject to high temp applications?

Answer 12

Graphite greases are used for high temp applications

Question 13

How much should you fill a bearing with grease? (%)

Answer 13

Packing bearings. Fill to 70-80%

Question 14

Answer 14

heavy landing

Question 15

Answer 15

brinelling

Question 16

Answer 16

indentations on the race-way due to load transferred through the bearing when static
False Brinelling - caused by AMBIENT VIBRATION & NO LUBRICATION - no hyrdo-dynamic film-Metal to Metal contact. The combination of metal to metal contact & vibration creates a wear pattern that mimics BRINELLING
(When a bearing is not operating it is subject to FALSE BRINELLING in its box or in the machine)

Question 17

Answer 17

lightly packed with grease
Bearings should be packed 70% to 80% full

Advantages of Grease - Bearings can be pre-lubricated - no need for LUBRICATION SYSTEM./ Requires Less Maintenance./ Not as difficult to seal as oil lubrication system./ Remains in contact to bearing components better than oil.
Disadvantages of Grease: LESS EFFICIENT AT CONDUCTING HEAT away from the bearing as effective as OIL. Increases initial TORQUE means RUNNING TORQUE IS SLIGHTLY HIGHER. SPEED LIMITS FOR GREASE ARE LOWER THAN OIL LUBE (Grease tends to cause overheating at high speed)

Question 18

Answer 18

oscillate and remove slowly to listen for roughness
Feel Test - Rotated slowly by hand and listen for roughness
Run Test - Run on shaft at 500 to 1000 rpm and applying AXIAL & Radial LOADS IN EITHER DIRECTION

Question 19

Answer 19

clean, warm, dry compressed air

Question 20

Answer 20

Spalling

Spalling - Flaking of the surface layer of the raceway caused by Thermal & Shear streeses or ingress of FOD, material flaking away (evidenced by vibration & noise) after a time these stresses cause cracks which extend up to the surface as the roller’s elements pass over the cracks fragments of material break away

Question 21

Answer 21

high temperature applications

Question 22

Answer 22

reject bearing
Overheating & Lubrication Failure - Discolouration of the rings, rollers & cages (Temp in excess of 400^C) restricted flow & excessive temperatures degrade the chemical composition of the grease

Question 23

Answer 23

Option A: are susceptible to brinelling

Question 24

Answer 24

Option C: A cracked ring

Question 25

Answer 25

Option B: heavy landing

Question 26

Answer 26

Option B: shallow smooth depressions caused by the rollers being forced against the cup, due to overtorquing

Question 27

Answer 27

Option B: both radial and axial loads

Question 28

Answer 28

Option C: brinelling

Question 29

Answer 29

Option C: a soft steel or brass tube drift

Question 30

Answer 30

Option B: sodium based greases ''Graphite is added to sodium based greases''

Question 31

Answer 31

Option B: indentations on the race-way due to load transferred through the bearing when static

Question 32

Answer 32

Option C: lightly packed with grease

Question 33

Answer 33

Option C: oscillate and rotate slowly to listen for roughness

Question 34

Answer 34

Option A: Radial

Question 35

Answer 35

Option C: white spirit

Question 36

Answer 36

Option B: clean, warm, dry compressed air

Question 37

Answer 37

Option A: thrust loads, thus limiting axial movement

Question 38

Answer 38

Option C: Spalling

Question 39

Answer 39

Option B: Needle bearings

Question 40

Answer 40

Option B: high temperature applications ''Graphite greases are used in high temperature applications''

Question 41

Answer 41

Option B: must be degaussed before use

Question 42

Answer 42

Option B: Nickel ''Outer rings are made from high carbon chromium alloy steel. Inner rings are made from low carbon nickel alloy steel and deep case carborized''

Question 43

Answer 43

Option A: Reject bearing

Question 44

Answer 44

Option A: Reject bearing

Question 45

Answer 45

Option C: the outer ring can be removed from its housing for inspection

Question 46

Answer 46

1/ Lying flat

Question 47

Answer 47

A. a cracked ring

Question 48

Answer 48

C. rotating slowly by hand

Question 49

Answer 49

C. rejection of the bearing

Question 50

5. A watermark on a bearing indicates A. bearing running dry B. intergranular corrosion C. lack of lubrication

Answer 50

B. intergranular corrosion

Question 51

Answer 51

A. pink

Question 52

Answer 52

1/ rejection of the bearing

Question 53

Answer 53

3/ the inner race

Question 54

Answer 54

1/ the outer race

Question 55

Answer 55

2/ on the load carrying surface

Question 56

Answer 56

1/ metallic particles in suspension

Question 57

Answer 57

3/ skidding under high load

Question 58

Answer 58

1/ the engine oil system

Question 59

Answer 59

2/ higher vibration readings

Question 60

Answer 60

1/ incorrect transport

Question 61

1. Which bearing type would normally carry the heaviest loads? 1/ air bearings 2/ roller bearings 3/ ball bearings

Answer 61

2/ roller bearings Note: r for roller - radial ball bearings -thrust loads

Question 62

2. Needle roller bearings are limited to only one type of load 1/ radial loads 2/ axial loads 3/ linear thrust loads

Answer 62

1/ radial loads radial loads - r for radial

Question 63

3. The most important factor in determining a bearings ability to carry axial loads is the: 1/ angular contact 2/ the internal clearance 3/ the available space

Answer 63

1/ angular contact

Question 64

4. A hardy spicer coupling is also known as: 1/ self aligning bearing 2/ silent running coupling 3/ a universal/constant velocity bearing

Answer 64

3/ a universal/constant velocity bearing

Question 65

5. Which type of bearing is more rigid: 1/ ball bearing 2/ roller bearing 3/ air bearing

Answer 65

1/ ball bearing

Question 66

6. How do we position bearings for storage: 1/ Lying flat 2/ On their side 3/ Stacked side by side

Answer 66

1/ Lying flat

Question 67

7. A Hardy Spicer coupling has what type of bearing? a) Plain bearings b) Ball bearings c) Needle bearings

Answer 67

c) Needle bearings

Question 68

8. Needle roller bearings A. can accept a small amount of misalignment B. are susceptible to brinelling C. are designed to carry axial loads

Answer 68

B. are susceptible to brinelling

Question 69

9. When rotating a ball bearing by hand, a regular click indicates A. a cracked ring B. damage to the balls C. intergranular corrosion in the outer ring

Answer 69

A. a cracked ring

Question 70

10. A journal load is: A. Compression B. radial C. Axial

Answer 70

B. radial

Question 71

What kind of bearing is used in a landing wheel? A. Needle roller bearing B. Tapered roller bearing C. Caged ball bearing

Answer 71

B. Tapered roller bearing A tapered roller bearing handles radial loads and axial loads in one direction only -> used in pairs

Question 72

Where are needle roller bearings used?

Answer 72

Where there are space restrictions

Question 73

14. Loads on tapered roller bearings are: A. thrust only B. radial only C. radial and thrust

Answer 73

C. radial and thrust

Question 74

A self aligning bearing is a A. angular bearing B. precision bearing C. radial bearing

Answer 74

A. angular bearing

Question 75

A crankshaft would be fitted with a A. cylindrical roller bearing B. taper roller bearing C. spherical roller bearing

Answer 75

cylindrical roller bearing

Question 76

Where heat is likely to be transmitted through a bearing A. group 2 bearings are used B. group 4 bearings are used C. group 3 bearings are used

Answer 76

B. group 4 bearings are used

Question 77

Shielded ball bearings are inspected by: A. running at operating speed and listening for signs of wear B. dismantling and inspecting C. rotating slowly by hand

Answer 77

C. rotating slowly by hand

Question 78

Thrust bearings take: A. radial loads B. journal loads C. sideloads

Answer 78

C. sideloads

Question 79

A single row ball bearing is best suited to accepting A. radial loads only B. axial loads only C. axial and radial Loads

Answer 79

C. axial and radial Loads Bal bearings take primarily thrust loads, some axial and small radial

Question 80

Taper roller bearings are used for which of the following purposes? A. To transmit radial loads whilst resisting axial movement B. To transmit thrust loads with radial loads C. To permit axial movement whilst resisting radial load

Answer 80

B. To transmit thrust loads with radial loads

Question 81

The stationary race of a journal bearing is normally: A. A clearance fit B. An interference fit C. A transition fit

Answer 81

B. An interference fit

Question 82

Damage to the shield of a bearing should result in A. no action B. replacement of the shield C. rejection of the bearing

Answer 82

C. rejection of the bearing

Question 83

A thrust bearing is designed so that A. it transmits radial loads, therefore limiting axial movement B. it transmits axial loads, therefore limiting radial movement C. it transmits axial loads, therefore limiting axial movement

Answer 83

C. it transmits axial loads, therefore limiting axial movement

Question 84

Which type of bearing seal is most appropriate to high temperature applications: 1/ Labyrinth seals 2/ Neoprene rubber type seals 3/ carbon type seals

Answer 84

1/ Labyrinth seals

Question 85

Plain bearings use: 1/ phosphor bronze 2/ High carbon steel 3/ Inconel steel

Answer 85

1/ phosphor bronze