Module 7.11 Flashcards

1
Q

slow rotation of bearings highlights what?

A

roughness due to damage, corrosion or wear

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2
Q

bearing tests are usually restricted to rotational checks for excessive backlash or free play, what direction is freeplay in?

A

axial or radial

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3
Q

if a bearing shows a fault or defect, what must be done?

A

remove or replace

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4
Q

how is preservation oil removed?

A

solvent bath

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5
Q

how is heavy grease, carbon or oil removed ?

A

in a soak bath

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6
Q

what is the final cleaning method?

A

ultrasonic bath

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7
Q

what must be done to the bearing if it is not going to be used immediately?

A

coated with rust preventing oil

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8
Q

what is likely to be grounds for any replacement of a bearing?

A

any flaw of defect

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9
Q

what properties must a lubricant have?

A

-reduces friction and abrasion
-reduces heat from friction
-prolongs life
-prevents rust
-keep foreign objects away from rollers

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10
Q

what lubricant is a better choice than grease for high rotational speeds?

A

oil is for high RPM. grease gets very hot at high RPM

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11
Q

how is loss of lubricant stopped?

A

retaining device
-labrynth seals
-felt
-rubber washers

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12
Q

most bearings are shielded or sealed, what must be done if evident lubricant has been washed out or lost?

A

replaced

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13
Q

grease nipples are provided for some bearings, what must be done before applying through the nipple?

A

wiped clean to prevent dirt ingress

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14
Q

what type of bearing is on a wheel hub? how is this regreased?

A

tapered roller bearing, usually regreased by hand

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15
Q

what is hydrodynamic lubrication?

A

load carrying surfaces separated by a thick film of lubrication to reduce friction

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16
Q

what is hydrostatic lubrication? and what does it not require?

A

high pressure oil or air to separate surfaces. Doesn’t require relative motion

17
Q

what is boundary lubrication and why is it important?

A

thin layer of lubrication between mating parts. Viscosity is not important, however lubricity is

18
Q

what is solid film lubrication? how is it applied and what are the benefits?

A

paint like coatings are applied by spraying, dipping or brush. film repels water, reduces friction and increases wear life.

19
Q

what is true brinelling?

A

regularly spaced indents with a vibraion increase

20
Q

cause of true brinelling?

A

-loads from incorrect mounting
-debris
- excessive static overload or impact loads

21
Q

rectification of true brinelling?

A

avoid unnecessary shock or impact loads

22
Q

what is false brinelling?

A

hollow spots on the raceway that resemble true brinelling

23
Q

what is the cause of false brinelling?

A

vibration in a static state, which causes metal to metal contact. poor luibrication

24
Q

how is false brinelling rectified?

A

reduce vibration by preloading,
use proper lubrication

25
what is burnishing?
splits or cracks in rolling elements or bearing rings
26
what causes burnishing?
-insuffcient lube - excessive loads and impacts - overheating by movement and rapid cooling - very loose fits
27
what does overheating look like?
discolouration of elements from gold to blue
28
how is burnishing rectified?
- prevent movement - correction of fit - correct lube
29
what causes overheating?
poor lube, heavy electrical loads and insufficient cooling
30
how do you rectify overheating?
prevent overload, serviceable lubricant system, supplemental cooling.
31
what does galling look like? and caused by?
metal to metal contact, metal transfer. looks like skidding due to overspeed
32
what is the rectification of galling?
prevent overload and have a serviceable lubing system
33
what is spalling?
breakdown of surface due to cyclic loading
34
what is wear caused by?
worn surface and dimensions are reduced component to other portions, caused by FOD, poor lube ect.
35
what bearings are more suceptible to damage?
moving bearings
36
what is one way to rectify electric damage?
prevent current from passing through
37
how does electric damage appear?
dark brown, greyish black corrugating or craters on raceway, balls have dark discolouring only.
38
what does corrosion on bearings look like and what is it caused by?
black pitting marks or reddish brown marks, caused by moisture and contamination.