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GAP Fundamentals > Lubrication > Flashcards

Lubrication Flashcards

1
Q

What is lubrication trying to accomplish?

A

Reduce:
-friction
-amount of mechanical energy to do work
-energy dissipated as heat
-reduce wear and corrosion

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2
Q

Dampen Shock

A

-shock loading is mainly a concern in gears.

-Viscosity increases with a pressure increase.

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3
Q

How does lubrication reduce corrosion?

A
  • Acts as a preservative for non-operating equip.
  • Provides a protective film for operating equip.
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4
Q

Examples of ‘Seal Outs’

A

-seal oil
-Gland sealing steam on main turbine

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5
Q

2 Different types of Lubrication Films characteristics?

A

-Adhesion
-Cohesion

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6
Q

What’s dry film?

A

-Natural lube (gasses,water vapor)
- NOT IDEAL

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7
Q

What’s mixed film?

A

-Some lube & some metal-to-metal contact

-single layer of lube

-high friction (bad)

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8
Q

What’s boundary film?

A

-Thicker lube and some metal-to-metal contact

-Common during startup/shutdown

-when components start to move, will draw lube between them.

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9
Q

What’s full film?

A

-Surfaces completely separated

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10
Q

What are two types of full film?

A

-Hydrodynamic: maintains separation of loaded surfaces due to exerting a higher psi and viscosity undue increased loads

-Hydrostatic:
•provided from an outside source
•used for slow, heavy loads

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11
Q

What is friction?

A

-The microscopic roughness on materials

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12
Q

What’s static friction?

A

-Exists between a body at rest and the surface upon which it rest.

-Must be overcome to START a body in motion.

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13
Q

What’s kinetic friction?

A

-Exist between moving bodies or between one moving body and one stationary body

-Must be overcome to KEEP a body in motion.

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14
Q

What’s different types of Kinetic friction?

A

-Sliding friction (bad)
-Rolling friction (better)
-Fluid friction (Good!)

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15
Q

What’s adhesion wear?

A

-Where metallic surfaces slide against each other under pressure.
-Bonds form and then break away

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16
Q

What’s abrasive wear?

A

-adhesive wear can cause this.
-When loose material is caught between sliding surfaces, causing gouging.

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17
Q

What’s an oil wedge?

A

-A layer of oil formed around a journal when it starts rotating.
-‘Full film layer’ at full speed
-Created with cohesion,adhesion and viscosity

18
Q

Liquid Oil

A

-Mineral oils made from crude oil (most common)

-Also oils made from animal or veggie fat.

19
Q

How are lubricants chosen for specific applications?

A

-Based on physical and chemical properties.

20
Q

What’s Viscosity?

A

-The tendency of a fluid to resist flow.

21
Q

How does viscosity change?

A

Temperature: Hot=runny
-inverted

Pressure: ‘heavy’/high psi=slow/thick
-Directly affects

22
Q

What are light oils used for?

A

-High speed
-Low pressure
-Low temp.

23
Q

What are heavy oils used for?

A

-Low speed
-High pressure
-High temp.

24
Q

Viscosity Index (VI)

A

-Keep it 100%/ 100(Vi) = never changes

-0(Vi)= changes the most

25
Q

Pour Point

A

-The lowest temp. at which oil will flow from a container

-High viscosity, high pour point.

26
Q

Flash Point

A

-The temp when oil is vaporized enough to ignite momentarily

-Need a spark.

-Low flash point= oil easily vaporized.

27
Q

Fire Point

A

-The temp when oil will continue to burn
-Higher temp than flash point.

28
Q

Auto-Ignition Point

A

-when the flammable vapors from oil will burn
-No spark required

29
Q

Demulsibility

A

-A measure of ability for oil and water to separate.

30
Q

What is grease?

A

-Semi-solid
-oil as basic lubricant
-thickener that supplies body(soap)
-additive that enhance properties
(Graphite,asbestos,zinc)

31
Q

Properties of Grease?

A

-Hardness
-Dropping point(melting point)
-Pumpability
-Water resistance
-Stability

32
Q

Type of solid lubricants?

A

-teflon tape
-graphite tape

33
Q

Gas lubricants

A

-required for high separation or high temp. conditions.

-Examples: jet engines or furnaces

34
Q

What are forms of manual lubrication

A

-Oil can
-Hand pump
-Grease gun

35
Q

What are forms of Gravity/drip feed?

A

-Container holding lubricant above equip.
-Adjustable needle valve
-Vibrating pin
-Wick oiler
-Trico bubbler

36
Q

How can over filling occur in Trico bubblers?

A

-repeated removal and replacement of bubbler

side note
-only add oil when level is less than 1/3 of the bubble level.

37
Q

Methods of natural lubrication?

A

-Splash oilers
- Ring oilers

38
Q

Methods of pressure/force feed lubrication?

A

-Wet sump (internal to system)
-Dry sump (separate from system)
-Air line lubricators (enters by Venturi as a mist)

39
Q

Lubrication failures occur due to?

A

-Chemical decomposition
-Contamination (particle)
-temperature (creates varnish/lacquer)
-inadequate flow
-water/air in oil

40
Q

Telltale symptoms of improper lubrication:

A

-High temp
-vibration
-noisy components
-component failure

41
Q

Gravity settling

A

-oil purification
-simple and slow process
-can reduce time by heating it.

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