Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Millwright Block 2 (harmonized) NS > Plain/friction Bearings > Flashcards

Plain/friction Bearings Flashcards

1
Q

What does plain bearings rely on to prevent the journal and bearing from contacting each other and reduce friction?

A

Film of oil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a plain bearing typically made up of? (2)

A

Journal
Bushing/shell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is unique about plain bearings?

A

No rolling elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the two main types of loads plain bearings support?

A

Radial
Axial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What load does journal bearing a typically support?

A

Radial load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What load does thrust bearings typically support?

A

Axial loads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of plain bearings? (2)

A

To hold the journal in the required location
Support the intended load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the journal?

A

The part of the shaft in contact with the bearing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the function of the journal?

A

Used to support a radial load on a shaft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is another name for a shaft collar?

A

Thrust collar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a shaft collar used in conjunction with?

A

Thrust bearing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

If the axial forces are to be controlled in two directions how is the assembly designed with the use of shaft collars?

A

1 collar located between 2 thrust bearings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

If the axial forces are to be controlled in one direction how is the assembly designed with the use of shaft collars?

A

The collar is located against one thrust bearing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the term bearing or journal bearing used to describe?

A

The bushing or shell that fits around the outside of the journal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is clearance between a journal and bearing required? (2)

A

Lubrication
Prevent binding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When is a thrust bearing used to locate a shaft?

A

When axial load is present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When axial load is present what type of friction bearing is commonly used

A

Thrust bearing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why is a thrust bearing used when axial load is present?

A

Locate a shaft in a specific axial position without interfering with the shafts rotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Where is a thrust bearings location on a shaft?

A

Near the component requiring accurate axial location control
(Typically the coupling)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How many thrust bearings are required on a shaft?

A

Only one per direction of axial thrust

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the two components that make up a linear bearing?

A

Guide/rail
Bushing/carriage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the guide in terms of linear bearings?

A

The fixed part of the machine that has a smooth uniform shape that the carriage slides along

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the carriage in terms of linear bearings?

A

The component that sits on or around the guide and slides along it’s length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are journals commonly made from?

A

The same material as the shaft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What material are bearings made from?
Softer material than the shaft
26
Why are bearings made from softer material than the shaft?
They are the sacrificial components
27
What are the considerations made when choosing a material for friction bearings? (9)
Compressive strength Fatigue resistance High embeddability Deformability (conformability) Wettability Thermal conductivity Corrosion resistance Bondability Compatibility
28
What does compressive strength refer to in terms of friction bearing material? (2)
Strong enough to support the shaft load at maximum operating Not so great that the west resistance is inadequate
29
When wear resistance is high what becomes lower?
Compressive strength
30
When compressive strength becomes higher what becomes lower? (2)
Wear resistance Embeddability
31
What does fatigue resistance refer to in terms of friction bearing material?
The resistance to cracking and flaking by loads the increase and decrease in rapid cycles
32
How is fatigue resistance in a friction bearing increased?
Keeping liner material as thin as possible to allow the backing to handle the stresses
33
What does embeddability refer to in terms of friction bearing material?
How well a material handles contaminants without failing
34
When embeddability becomes higher what becomes lower?
Compressive strength
35
What does deformability refer to in terms of bearing material?
Allows a material to yield to a misalignment or imperfection in the shaft (such as change in diameter)
36
What does wettability refer to in term of friction bearings?
The ability to retain a film of lubricant
37
What does thermal conductivity refer to in terms of friction bearings? (2)
Allows rapid transfer of heat due to fluid friction prevents local hot spots
38
What does corrosion resistance refer to in terms of friction bearings?
Resist corrosion from the acids in the oxidized oil
39
What does bondability refer to in terms of friction bearings?
Bearing material to form a good metallurgical bond to the backing material
40
What does compatibility refer to in terms of friction bearings?
Materials must not seize or weld to the journal under rubbing conditions
41
What is another name for Babbitt
White metal alloy
42
What can Babbitt alloys be composed of?
Tin Lead Copper Antimony Bronze
43
What does lead provide to Babbitt?
Bearing properties
44
What does bronze or copper provide to Babbitt?
Strength
45
What are the 8 advantages to Babbitt?
Compressive strength Embeddability Conformability Wettibility Thermal conductivity Corrosion resistance Bondability Low cost
46
What is the limitation of Babbitt?
Low fatigue resistance
47
Where is Teflon used in friction bearings? (2)
Light duty bushings Or Bronze matrix for strength
48
What are the 3 advantages to Teflon?
Self lubrication Chemically inert Useful with soft journals
49
What does chemically inert mean?
Withstand chemical attack
50
What are the 3 disadvantages to Teflon?
Limited by temperature Emits poisonous gas when burned Absorbs water
51
What does aluminum provide in an aluminum/tin alloy?
Strength
52
What does tin provide in an aluminum/tin alloy?
Bearing material
53
What was the aluminum/silcone alloy created for?
Extra strength
54
What are the 6 advantages to aluminum/tin or aluminum/silcone alloys?
More embeddable than copper/lead or lead/bronze More corrosion resistant than copper/lead or lead/bronze Less expensive than copper or bronze Softer than copper or bronze alloys Higher load rating than Babbitt Bond able to steel
55
What are the disadvantages to aluminum/tin or aluminum/silcone alloys? (2)
Less embeddability and conformability than Babbitt
56
What bearing component is located on a machine shaft and supports a radial load?
Collar
57
What material property ensures that the journal and bearing do not weld together?
Compatibility
58
What bearing material has the best load rating?
Aluminum/tin
59
What determines the type of bearing design? (4)
Load Machine speed Installation requirements Cost
60
Where are plain bearings typically used?
To support high loads due to their large surface areas
61
What are the 3 most common radial load types?
Stationary Oscillating Reciprocating
62
What degree does a oscillating load move?
Shifts through an arc less than 180 degrees
63
Where is the lubricant film on a stationary radial load?
One area of the bearing
64
How many directions is the load on a stationary radial load?
Typically 1
65
In terms of the bearing, where is the load supporting film on a oscillating load?
The film must move along the loaded area
66
What is the difference between the fluid film between a stationary load and an oscillating load?
The fluid is much thinner but stronger on the oscillating load
67
How does an oscillating load affect the bearing clearance?
Clearances are much smaller
68
Why is the cleanliness of the oil more critical in bearings with an oscillating load?
The film is thinner
69
In terms of bearings what degree does the load shift in a reciprocating load?
The load shifts 180 degrees from one side of the bearing to another
70
What are the two configurations journal bearings can come in?
Split bearing Bushing
71
What features does a thin shell split bushing have? (4)
Flexible Thin overly on steel backing Must be seated in a strong housing with an accurate bore
72
What’s the characteristics of a split bushing?
Light weight With stands high loads
73
What is a bushing?
A type of plain bearing that has not been split
74
What are bushing typically designed to handle?
Radial or axial loads
75
How can you tell if a bushing can support axial loads by its self?
It will be flanged
76
What does a wrapped bushing consist of?
Thin steel shell lined with a soft bearing material
77
What are the advantages of a wrapped bushing? (2)
High fatigue strength Available in pre finished sizes
78
Where should pre finished bushings be used? (2)
Only in light loaded Non crucial applications
79
What are solid bushings?
Bushings bored out of a solid piece of bearing material
80
What are the advantages to solid bushings? (3)
Can be bored to non standard size Easily made Can accommodate deep lubricant grooves
81
What is important to do after installing solid bushings?
Ream to their correct size
82
What is the limitations of solid bushings?
Not as much fatigue strength of wrapped bushings
83
What are floating bushings?
Bushings that consist of an outer bushing with a loosely fitted inner bushing
84
Where can floating bushings be used? (2)
Lightly loaded / High speeds Or Heavily loaded / low speeds
85
How can you help stabilize a floating bushing?
Film of oil between their inner and outer bushings
86
What are water lubricated bushings?
Bushings made on non metallic material that are slippery when wet
87
What materials can be used for water lubricated bushings? (3)
Rubber Nylon PTFE
88
What type of loads are water lubricated bushings suited for?
Only very light
89
What are pre lubricated bushings?
Either made of porous material soaked in lubricant or have a lining with pockets filled with lubricants
90
How are porous bronze bushings charged?
Soaking in oil at 90 degrees Celsius for half an hour
91
How much oil can porous bronze hold up to?
Max 30% of its volume
92
What is the limitations of pre lubricated bushings? (3)
Poor heat distribution Not good for high temps Only good for light loads
93
What are dry lubricated bushings?
Bushings made of a slippery material
94
What are the features of dry lubricated bushings? (3)
Can run dry Solid or lined Available in a broad range of materials for different needs
95
What are the limitations of dry lubricated bushings?
Not good for high speeds or heavy loads
96
What are hydrodynamic bearings?
A widely used plain bearing, Designed to develop full film lubrication when a journal is at operating speeds
97
What are the characteristics of a hydrodynamic bearing? (3)
Both split or bushing Oil inlet Supports full film
98
How do you check the contact area of a plain bearing?
Look for the polished rub area

Millwright Block 2 (harmonized) NS (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions