Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IDIS 303 > Chapter 7 - Bearings > Flashcards

Chapter 7 - Bearings Flashcards

1
Q

Main function of a bearing

A

Provide a smooth, low-friction motion between two surfaces.

Used to support shafts and allow their free rotation.

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

Types of motion

A

Rotary

Linear

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

Rotary motion

A

Shaft turning in a housing

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

Linear motion

A

One machine element moving across another.

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

Types of Loads

A

Radial

Thrust or Axial

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

Radial Load

A

Right angles to the shaft or bearing’s axis of rotation.

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

Thrust or Axial Load

A

Loads are applied parallel to the axis of rotation.

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

Two basic types of bearings

A

Plain

Rolling Element

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

Bearings that support loads perpendicular to their axis are called

A

Radial Bearings

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

Support loads parallel to their axis of rotation are termed

A

Thrust Bearings

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

Types of bearing from design point of view:

A

Plain bearing
Ball bearing
Roller bearing

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

Plain bearings

A

Most basic type of bearing.
Limited to lighter loads and slower speeds.
Functions as a tight-fitting cylinder, usually stationary, that encloses and supports a moving member, generally shaft or journal.
Support radial or thrust loads.
Journal/sleeve = radial type

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

Plain Bearing Applications

A

Industrial machinery
Automobiles
Home applications
Construction equipment

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

Plain-Bearing Lubrication

A 
Generally are lubricated with grease.
Boundary
Mixed-film
Full-film or hydrodynamic
Hydrostatic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Boundary Lubrication

A

Bearing and shaft rub together with only a thin film of lubricant on the surfaces. Grease lubricated bearings generally operate this way.

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

Mixed-film Lubrication

A

Part of load (where shaft and bearing are closest) is supported on a boundary film and the remaining part is supported by hydrodynamic pressure.

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

Full-film or hydrodynamic Lubrication

A

A thick, continuous film of self-pressurized lubricant separates the shaft from the bearing with no metal-to-metal contact.

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

Hydrostatic Lubrication

A

External pumps supply pressure to the lubricant, providing a full film to prevent metal-to-metal contact.

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

Self-Lubricating Bearings

A

In applications where relative motion is insufficient to circulate oil or grease through a bearing.
Used where temperatures exceed the scope of conventional lubricants.

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

Rolling-Element Bearings

A

Rely on either balls or rollers.
Their rolling motion produce less friction than plain bearings.
Low starting friction.
Available for radial loads, thrust loads, or a combination.

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

Types of Ball Bearings

A

Angular contact bearings
Thrust ball bearings
Unground ball bearings
Thin section bearings

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

Angular contact bearings

A

Accepts high thrust load in combination with moderate radial load. Single row.

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

Thrust ball bearings

A

Carry primarily thrust loads.

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

Unground ball bearings

A

Provides high-speed and high-load-carrying capabilities.
Have fewer parts, cost less, and can reduce installation costs.
Available in radial, thrust, and combination loads.
Cheap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Thin section bearings

A

Where space and weight must be conserved.
Ball and roller types.
Designed for light to medium-duty drives operating at medium and slow speeds.

26
Q

Roller Bearings

A

Generally support heavier loads than comparably sized ball bearings.
Capable of handling high-impact or shock loads.
More sensitive to misalignment.

27
Q

Roller Bearing Types:

A

Cylindrical
Needle
Spherical
Tapered

28
Q

Cylindrical roller bearings

A

Has the highest radial load capacity and speed capability.
Non-locating. Enables axial movement.
For general use, a roller length equal to the roller diameter provides the best balance of load and speed capabilities.

29
Q

Needle roller bearings

A

Have a much smaller diameter-to-length ratio.
Carry heavy radial loads in a minimal amount of radial space.
Load capacity is higher than most single-row ball or roller bearings.

30
Q

Types of Needle Roller Bearings

A

Drawn-cup
Caged
Cam (or track) follower

31
Q

Drawn-cup Needle roller bearing

A

Roller ends are shaped so that lips on the outer race keep them from falling out.
Higher load-carrying capacity than the basic type because the grease-retained rollers have spherical ends.

32
Q

Caged needle roller bearing

A

Designed for heavy-duty, high-speed
applications.
The heaviest-duly version.

33
Q

Cam (or track) follower

A

A special, heavy-duty needle roller bearing with a heavy outer race.
There are two basic mounting types: one with an integral stud for cantilever mounting, the other, an inner race for yoke mounting.

34
Q

Spherical roller bearings

A

Usually containing one or two rows of rollers within a spherical outer raceway, spherical roller bearings.
Support high radial or combined radial and thrust loads.
Suitable for heavy-duty applications.

35
Q

Tapered roller bearings

A

Carry heavy radial loads, thrust loads, or both.
Can tolerate some minor misalignment.
For more capacity, two row bearings are used.

36
Q

Tapered roller bearings uses

A 
Appliances
Machine tools
Mobile equipment
Turbines
Industrial machinery
37
Q

Mounted Bearings

A

Eliminates the need to select and assemble components installed in a sturdy housing.
Provides shaft support for radial, thrust, or combination loads.

38
Q

Types of Mounted Bearings

A

Pillow blocks
Flanged cartridges
Cylindrical cartridges
Take-up units

39
Q

Pillow Blocks

A

Most common type of mounted unit.
Have the plane of the mounting base parallel to the shaft.
Used on vertical or horizontal surfaces or on an inclined plane.

40
Q

Flanged cartridge blocks

A

Usually mounted on vertical surfaces where a shaft pauses through a machine frame at a right angle.

41
Q

Mounted Plain Bearings

A

They are commonly used in linkages and low-speed applications where low friction is required.

42
Q

Mounted Rolling-Element Bearings

A

Typically have spherical outer, surfaces that compensate for angular shaft misalignment.
The simplest types mount with a slip fit collar and setscrew.

43
Q

Magnetic Bearings

A

Can obtain frictionless motion, unlimited speed and undetectable vibrations.

44
Q

Parts of Magnetic Bearings

A

Bearing Actuators
Sensors
Controller and control algorithms

45
Q

Types of Magnetic Bearings

A

Radial magnetic bearing
Magnetic thrust bearing
Active magnetic bearings

46
Q

Radial magnetic bearing

A

Generates an attractive force to levitate the shaft.

Consists of laminated actuators, each having two poles wound by a coil.

47
Q

Magnetic thrust bearing

A

Solid steel disc is attached to the shaft with an annular stator on either side.

48
Q

Active magnetic bearings

A

Shaft position sensors are used to provide feedback to the control system.
Typically, inductive sensors in five axes (four radial, one thrust) are used.

49
Q

Magnetic Bearing Characteristics

A

No Lubricant.
Suited to machines operating in a vacuum, at high or low (cryogenic) temperatures or in corrosive process fluids.
Much higher surface speeds.

50
Q

Bearing Standards Organization

A

American Bearing Manufacturers Association

51
Q

Two standardized load ratings

A

basic load rating

static load rating

52
Q

Basic load rating

A

Defines the load that a group of bearings can endure for one million revolutions.

53
Q

Static load rating

A

Load that corresponds to a total permanent deformation of rolling clement and raceway of 0.0001 of the rolling-element diameter.

54
Q

Rating life

A

L10

90% of a group of bearings will complete at a given load and speed before fatigue failure occurs.

55
Q

Bearing life

A

Usually inversely proportional to hearing load and speed.

Virtually impossible to predict the exact life of a bearing.

56
Q

Shaft and Housing Fits

A

The inner ring (ID) must properly fit the shaft and the outer ring (OD) must properly fit the housing bore.

57
Q

Bearing selection major factors

A 
Load
Speed
Life
Noise and vibration
Misalignment
Temperature
Environmental conditions
58
Q

Inspection of Bearings

A

Check of bearings in operation

Inspection of bearings after operation

59
Q

Inspection when machine is running

A 
Bearing Temperature 
Operating sound of Bearing 
Vibration of Bearing 
Lubricant Selection 
Relubrication
60
Q

Non-locating means

A

Enables axial movement of the inner and outer ring to accommodate both thermal and axial expansion of the shaft and tolerances in the assembly

IDIS 303 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions