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Kemble > 7.11 Bearings > Flashcards

7.11 Bearings Flashcards

1
Q

Bearings are used to support what?

A

Shafts and axles

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2
Q

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

A

Journal or roller bearings

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3
Q

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

A

Pivot or axial bearings

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4
Q

The journal of a slider bearing operates in what?

A

Bearing box
Bearing bushing
Or directly in bearing body

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5
Q

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

A

Have sufficient lubrication

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6
Q

What does the amount of bearing play depend on?

A

The demands the bearing is subjected to

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7
Q

Characteristics of sliding bearings?

A

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

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8
Q

Disadvantages of sliding bearings

A

High starting resistance
Continuous maintenance

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9
Q

Five basic types of anti friction bearings?

A

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

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10
Q

What does lubricants prevent for bearing?

A

Prevents heating
Prevents corrosion on bearing surface

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11
Q

As a bearing rotates, the mating surfaces create what?

A

Lubricant film that separates components

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12
Q

What happens if you over grease a bearing?

A

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

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13
Q

Bearings are protected with what in shipping?

A

A preservative coating but is NOT a lubricant

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14
Q

Is the preservative coating on bearings compatible with lubrication?

A

Yes
It doesn’t need washing off prior to installation

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15
Q

What does excessive loads cause?

A

Premature fatigue

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16
Q

What else can cause early fatigue failure in bearings?

A

Tight fits
Brinelling
Improper preloading

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17
Q

What is the solution for bearings with excessive loads?

A

Reduce the load
Make a bearing with higher weight capacity

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18
Q

What are symptoms of overheating in bearings?

A

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

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19
Q

What can overheating cause for bearings?

A

Deformation of the balls and rings
Degrades and destroys the lubricant

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20
Q

What are common reasons for overheating in bearings?

A

Heavy electrical loads
Inadequate heat paths
Insufficient cooling or lubrication

21
Q

What does false brinelling of bearings indicate?

A

Excessive external vibration

22
Q

How do you correct false brinelling?

A

Isolate bearings from external vibration and using greases containing antiwear additives

23
Q

What is fatigue failure?

A

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

24
Q

Where can fatigue failure occur?

A

Can occur on inner ring
Outer ring
Balls

25
Q

How else can fatigue failure be recognised?

A

Vibrations that indicates abnormality

26
Q

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

A

Axial loads in one direction

27
Q

Angular contact bearings must be installed in what way?

A

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

28
Q

Symptoms of contamination of bearings?

A

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

29
Q

Some examples of contaminants?

A

Dust
Dirt
Abrasive substances

30
Q

What are some sources of contamination?

A

Dirty tools
Contaminated work areas
Dirty hands

31
Q

How to reduce chance of contamination?

A

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

32
Q

Symptoms of lubricant failure?

A

Discoloured blue or brown tracks and balls

33
Q

How are lubricant failures usually caused by?

A

Restricted lubricant flow

34
Q

Symptoms of bearing corrosion

A

Red/brown colour on balls, cages or bands

35
Q

How to reduce corrosion for bearings?

A

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

36
Q

What are the most prevalent causes of misalignment?

A

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

37
Q

What indicates a tight fight?

A

Temperature rise

38
Q

4 general instructions for bearings?

A

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

39
Q

When handling a bearing what should you remember?

A

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

40
Q

How should you store a bearing?

A

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

41
Q

What should the storage area be like for bearings?

A

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

42
Q

What is the leading failure of bearings

A

Contamination

43
Q

What is a symptom of lubricant failure

A

Discoloured blue/brown ball tracks

44
Q

What is a symptom of corrosion within bearings

A

Red/brown areas or balls

45
Q

How can misalignment be detected

A

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

46
Q

How can you tell if there is a loose fit

A

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

47
Q

Why are tight fits accompanied by

A

High temperatures

48
Q

What is a symptom of overheating

A

Balls and cages go from gold to blue

Kemble (39 decks)

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