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Millwright Level 2 > Lubrication > Flashcards

Lubrication Flashcards

(87 cards)

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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
When grease tends to shear in the direction of rotation is is called what?
Directional fluidity
26
How do you initially pack a bearing?
By hand
27
How full do you pack a bearing housing?
One-third full for high speed, One-half full for slow speeds
28
A single reduction required a _____ oil to suit the input gears
Light oil
29
A compound needs a _______ oil to suit the output gear mesh
Heavier oil
30
In an oil bath how high does the fluid go?
Covers the outer race but does not cover the centre point of the lowest ball or roller
31
Over oiling produces what?
Churning and temperature rise
32
Is oil or grease better for heavy loads at slow speeds?
Grease
33
What is a good lubricant for very high speeds?
Oil
34
What cutting oils can only be used on ferrous metals?
Active
35
What cutting oils can be used on ferrous and non ferrous metals?
Inactive
36
What oils are used for grinding?
Chemical
37
What type of lubrication is loaded to the extent that deformation takes place?
Elasto-Hydrodynamic
38
What type of lubrication does not completely separate the surfaces?
Boundary
39
Hydrodynamic lubrication uses the rotation of the shaft to form what?
An oil wedge
40
What three factors affect the thickness of the hydrodynamic film in loaded area?
Speed, viscosity, load pressure
41
What three factors affect viscosity ?
Temp, pressure, speed
42
What are the differing units of viscosity?
centistoke and SUS (SSU)
43
The lowest temperature at which an oil is observed to flow is called what
The pour point
44
The lowest temperature at which the vapour above an oil ignites when a flame passed over it is called what
Flash point
45
Low temp engine grades are indicated by what letter
W
46
What are the two types of petroleum based oils?
Paraffin and Naphtha
47
This is the most commonly used base oil
Paraffin
48
These oils are made from at least 10 chemical bases
Synthetic
49
Why are detergents not recommended for high temp applications?
They leave a residue called Ash
50
This tells you how well an oil can maintain its viscosity over a range of temperatures
Viscosity index
51
What percentage of bearing failures are due to incorrect lubrication?
36%
52
What lubrication system is used for low surface speeds?
Bottle lubrication
53
What is the oldest method of applying oil and for bearings with a 2" or smaller shaft?
Table wick feed oiler
54
What lubrication system delivers oil from a reservoir by gravity?
Drip Feed
55
What lubrication system uses a ring or chain for shafts smaller than 4"?
Ring or chain Oilers
56
What type of lubrication forces oil into the engine bearings?
Pressure lubrication system
57
What are the two types of Air activated lubrication systems?
Oil mist and air-oil
58
What lubrication system are used for elements difficult to access?
Block lubrication
59
When should you do on-line flushing?
Before startup of machine
60
A measure of grease stiffness is referred to as what?
Consistency
61
What is an example of a complex soap thickener?
Sodium thickener
62
What is an example of a compound soap thickener?
Lithium and calcium
63
What is the temperature range for petroleum base oils
-50C and 170C
64
The degree of stiffness in a grease is called what
Consistency
65
What temperature should the bearing not exceed after relubricating?
60C
66
What once-through system uses capillary action?
wick-feed oiler
67
The ability of a petroleum to mix with water is called what?
emulsibility
68
What are the two general groups of load capacity additives?
anti-wear and EP
69
What is the most common lubrication method in enclosed gear systems?
Splash lubrication
70
When oils react chemically with oxygen it is called what?
Oxidation
71
Oxidation produces these two classes of waste products
Varnish/sludge and Acids
72
Soft greases have ____ penetration numbers and ___ NLGI grades
High, Low
73
What type of grease is good where adhesiveness is required?
Aluminum
74
Should you add oil to water, or water to oil?
Oil to water
75
What is used for high speed operation, or temps below zero and above 93C (200F)
Oil
76
What type of lubrication do worm-wheel gears use?
Oil bath
77
Simple soap greases are made by combining a _____ ____ with a base metal
Fatty acid
78
Common greases have a dropping point that range from what
135C (275F) to 182C (360F)
79
What are the three kinds of cutting oils?
Straight, emulsifiable, and chemical
80
The property of reducing friction is known as what
Lubricity
81
The three types of fluid film lubrication are what
Full film, Elasto-Hydrodynamic, Boundary
82
A direct measurement of the force of resistance to flow is called
Absolute viscosity
83
Some types of synthetic oils are stable up to how many degrees?
250 C
84
What percentage of additives make up the oil?
22%
85
The oxidation rate of petroleum based oils doubles for every __ degrees over 55C
8 C
86
When greasing an increase in operating temperature of __ degrees above 70C cuts the relubrication interval in half
15 C
87
Name the 3 types of dry lubricants
Graphite, PTFE (Teflon), Molybdenum Disulphide

Millwright Level 2 (10 decks)

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