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Millwright Level 2 > Lubrication > Flashcards

Lubrication Flashcards

1
Q

What are the 3 types of friction

A

Sliding, Rolling, and Fluid

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2
Q

What kind of force causes unlike materials to stick together?

A

Adhesion

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3
Q

What kind of force cause molecules of like materials to stick together

A

Cohesion

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4
Q

When adhesive forces are strong oils rich in these molecules are said to be high in what?

A

Oiliness

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5
Q

What is the resistance to flow?

A

Viscosity

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6
Q

What happens when oil temperature rises?

A

Viscosity drops, oil thins out

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7
Q

What viscosity is a measure of viscosity affected by the density of the oil?

A

Kinematic

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8
Q

What is the most common method of measuring viscosity

A

Saybolt viscosimter

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9
Q

The higher the VI number the _______ the change in viscosity due to temperature

A

Smaller

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10
Q

Efficiency of the oil wedge depends on what?

A

Load, RPM, operating temp, clearance, viscosity, volume of lubricant, shaft surface finish

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11
Q

When the film of oil fails for a short time it’s called what?

A

Boundary lubrication

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12
Q

If you over lubricate a threaded hole what can happen?

A

Hydraulic lock

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13
Q

Additives and inhibitors are divided into these three groups

A

Air control, water control, load capacity control

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14
Q

Where are detergents usually found?

A

Gas and diesel engines

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15
Q

What are the two types of oil lubrication systems?

A

Once-through and enclosed

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16
Q

How to do you make approximate oil check?

A

Smell, touch, sight, magnet

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17
Q

What are greases generally thickened with?

A

Soap

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18
Q

Soap content for general greases are what percentage?

A

7% to 18% (low as 3% high as 50% for special greases)

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19
Q

What soap greases are good for damp conditions?

A

Calcium

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20
Q

What soap greases are good for dry conditions?

A

Sodium

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21
Q

What soap greases are good for water resistance, high temps, and most commonly used?

A

Lithium and Barium

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22
Q

What greases are recommended for high shock load nd high pressure?

A

EP extreme pressure

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23
Q

NLGI penetration numbers range from what?

A

Softest 000, 00, 0, 1, 2, 3, 4, 5, 6 Hardest

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24
Q

The temperature at which a grease becomes fluid enough to drip is called what?

A

Dropping point

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25
Q

When grease tends to shear in the direction of rotation is is called what?

A

Directional fluidity

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26
Q

How do you initially pack a bearing?

A

By hand

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27
Q

How full do you pack a bearing housing?

A

One-third full for high speed, One-half full for slow speeds

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28
Q

A single reduction required a _____ oil to suit the input gears

A

Light oil

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29
Q

A compound needs a _______ oil to suit the output gear mesh

A

Heavier oil

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30
Q

In an oil bath how high does the fluid go?

A

Covers the outer race but does not cover the centre point of the lowest ball or roller

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31
Q

Over oiling produces what?

A

Churning and temperature rise

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32
Q

Is oil or grease better for heavy loads at slow speeds?

A

Grease

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33
Q

What is a good lubricant for very high speeds?

A

Oil

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34
Q

What cutting oils can only be used on ferrous metals?

A

Active

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35
Q

What cutting oils can be used on ferrous and non ferrous metals?

36
Q

What oils are used for grinding?

37
Q

What type of lubrication is loaded to the extent that deformation takes place?

A

Elasto-Hydrodynamic

38
Q

What type of lubrication does not completely separate the surfaces?

39
Q

Hydrodynamic lubrication uses the rotation of the shaft to form what?

A

An oil wedge

40
Q

What three factors affect the thickness of the hydrodynamic film in loaded area?

A

Speed, viscosity, load pressure

41
Q

What three factors affect viscosity ?

A

Temp, pressure, speed

42
Q

What are the differing units of viscosity?

A

centistoke and SUS (SSU)

43
Q

The lowest temperature at which an oil is observed to flow is called what

A

The pour point

44
Q

The lowest temperature at which the vapour above an oil ignites when a flame passed over it is called what

A

Flash point

45
Q

Low temp engine grades are indicated by what letter

46
Q

What are the two types of petroleum based oils?

A

Paraffin and Naphtha

47
Q

This is the most commonly used base oil

48
Q

These oils are made from at least 10 chemical bases

49
Q

Why are detergents not recommended for high temp applications?

A

They leave a residue called Ash

50
Q

This tells you how well an oil can maintain its viscosity over a range of temperatures

A

Viscosity index

51
Q

What percentage of bearing failures are due to incorrect lubrication?

52
Q

What lubrication system is used for low surface speeds?

A

Bottle lubrication

53
Q

What is the oldest method of applying oil and for bearings with a 2” or smaller shaft?

A

Table wick feed oiler

54
Q

What lubrication system delivers oil from a reservoir by gravity?

55
Q

What lubrication system uses a ring or chain for shafts smaller than 4”?

A

Ring or chain Oilers

56
Q

What type of lubrication forces oil into the engine bearings?

A

Pressure lubrication system

57
Q

What are the two types of Air activated lubrication systems?

A

Oil mist and air-oil

58
Q

What lubrication system are used for elements difficult to access?

A

Block lubrication

59
Q

When should you do on-line flushing?

A

Before startup of machine

60
Q

A measure of grease stiffness is referred to as what?

A

Consistency

61
Q

What is an example of a complex soap thickener?

A

Sodium thickener

62
Q

What is an example of a compound soap thickener?

A

Lithium and calcium

63
Q

What is the temperature range for petroleum base oils

A

-50C and 170C

64
Q

The degree of stiffness in a grease is called what

A

Consistency

65
Q

What temperature should the bearing not exceed after relubricating?

66
Q

What once-through system uses capillary action?

A

wick-feed oiler

67
Q

The ability of a petroleum to mix with water is called what?

A

emulsibility

68
Q

What are the two general groups of load capacity additives?

A

anti-wear and EP

69
Q

What is the most common lubrication method in enclosed gear systems?

A

Splash lubrication

70
Q

When oils react chemically with oxygen it is called what?

71
Q

Oxidation produces these two classes of waste products

A

Varnish/sludge and Acids

72
Q

Soft greases have ____ penetration numbers and ___ NLGI grades

73
Q

What type of grease is good where adhesiveness is required?

74
Q

Should you add oil to water, or water to oil?

A

Oil to water

75
Q

What is used for high speed operation, or temps below zero and above 93C (200F)

76
Q

What type of lubrication do worm-wheel gears use?

77
Q

Simple soap greases are made by combining a _____ ____ with a base metal

A

Fatty acid

78
Q

Common greases have a dropping point that range from what

A

135C (275F) to 182C (360F)

79
Q

What are the three kinds of cutting oils?

A

Straight, emulsifiable, and chemical

80
Q

The property of reducing friction is known as what

81
Q

The three types of fluid film lubrication are what

A

Full film, Elasto-Hydrodynamic, Boundary

82
Q

A direct measurement of the force of resistance to flow is called

A

Absolute viscosity

83
Q

Some types of synthetic oils are stable up to how many degrees?

84
Q

What percentage of additives make up the oil?

85
Q

The oxidation rate of petroleum based oils doubles for every __ degrees over 55C

86
Q

When greasing an increase in operating temperature of __ degrees above 70C cuts the relubrication interval in half

87
Q

Name the 3 types of dry lubricants

A

Graphite, PTFE (Teflon), Molybdenum Disulphide

Millwright Level 2 (10 decks)

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