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Industrial Mechanic 2nd Block, Harmonized > Friction Bearings > Flashcards

Friction Bearings Flashcards

1
Q

_____ bearings have a sliding contact between a shaft and the bearing. A special, low friction material lines the housing and directly contacts and supports the shaft, separated by a thin layer of lubricant.

A

Friction Bearings

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2
Q

Friction bearings are also referred to as: (3)

A
  • Plain Bearings
  • Sleeve bearings
  • Journal bearings
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3
Q

The _____ of a bearing is its outer casing.

A

Housing aka Pillow block

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4
Q

the principal parts of a friction bearing are the: (4)

A
  • Base
  • Base bolt slots
  • cap
  • cap bolt holes
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5
Q

Housings can be made of one of the following materials: (3)

A
  • Cast iron
  • Cast steel
  • Fabricated steel
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6
Q

This housing material would be ideal for light to medium loads

A

cast iron

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7
Q

This housing material would be ideal for light to heavy loads

A

cast steel

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8
Q

This housing material is for special jobs

A

fabricated steel

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9
Q

the choice of bearing housing, and the friction bearing, depend on: (4)

A
  • Load
  • Rotational(rubbing) speed
  • direction of pull
  • support design
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10
Q

Bearings have a nominal size, such as 2 7/16”. This is the size of the:

A

bore

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11
Q

The dimension from the base to the shaft center is important for:

A

installation and alignment

Note: this is also known as the eye of the bearing

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12
Q

There are two kinds of flat bearings, which differ in their housings: (2)

A

solid and split bearings

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13
Q

Solid bearings are used when speed and load are:

A

low

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14
Q

solid bearings are used in locations where the load is applied to the ___ part of the bearing

A

top

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15
Q

Solid bearings must be slid on or off of the shaft, which means that the bearings must be installed as an:

A

assembled unit

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16
Q

A two bolt split bearing is used for what size load?

A

light to medium load

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17
Q

A two bolt split bearing is used for what size load?

A

medium to heavy load

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18
Q

____ bearing housings are used for drives in either of the following situations:

  • when a load is applied parallel to the horizontal
  • when the bearing is mounted on a vertical support
A

Angle bearings

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19
Q

Some heavy duty machines in industrial plants have the bearing housing base cast as an integral part of the machine. Either babbitted or fit with shells or liners. This is an:

A

Integrated bearing

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20
Q

What are the 3 join designs of split bearing housings? (3)

A
  • Flat joints
  • Gib in the joint
  • angle joint
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21
Q

When the split bearing housing joints have a “step” in them, they keep the cap from moving sideways. This combines the rigidity of a solid block with the advantages of split construction. What style joint is this?

A

Gib joints

Note: Allows bearing limited side loading

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22
Q

Journal bearings and pillow block bearings with anti-friction material liners are commonly used for ____ to ____ speed and for _____ to ____ loads.

A

low to medium speed

light to heavy loads

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23
Q

Journal bearings and pillow block bearings with anti friction material liners can be used for ultra high speeds with _____ lubrication only under exact conditions

A

Air jet lubrication

ex: main bearings on a turbine

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24
Q

when selecting bearing lining material, it should be: (5)

A
  • softer than shaft material
  • low coefficient of friction
  • wear-resistant
  • a good heat conductor, remain stable with heat changes
  • readily available
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25
Q

Metallic bearing materials must have a low:

A

coefficient of expansion

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26
Q

metallic bearing materials ____ ____ with water, mild acids, alkalis, salts, or other materials.

A

react chemically

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27
Q

Materials for metallic liners include: (5)

A
  • Babbitt
  • Brass
  • Bronze
  • Sintered Bronze
  • Aluminum
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28
Q

This metallic bearing liner material is for general use

A

Babbitt

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29
Q

These metallic bearing liner materials are for higher speeds and heavier loading than babbitt: (2)

A
  • Brass

- Bronze

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30
Q

This metallic bearing liner material is common in hydraulic pumps

A

Aluminum

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31
Q

This metallic bearing liner material is porous with a built in oil supply:

A

Sintered bronze

Note: oil to bronze ratio is 1:2 by volume

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32
Q

Non metallic bearing liners include: (3)

A
  • Nylon
  • Polyurethane
  • phenol laminates
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33
Q

Nylons, polyurethanes and other synthetic bearing materials are sometimes called _____ bearing materials

A

Plastic

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34
Q

The advantage of plastic bearings is that they are generally inert to most ___ and ____

A

Mild acids and alkalis

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35
Q

The lubricant for plastic bearings can be oil or grease, but ____ is sometimes used

A

Water

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36
Q

With ____ rubbing speeds and ____ operating temperatures, some grades of nylon run with no lubrication

A

Low and Low

Note: Plastic bearings have varying, but higher coefficients of heat expansion VS metallic bearing materials.

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37
Q

Some synthetic materials _____ when saturated with water

A

expand

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38
Q

This non-metallic bearing liner has layers of cotton or other natural fibers bonded with resin. They are strong, shock resistant, and compatible with most fluids

A

Phenol Laminates

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39
Q

______ is a common anti-friction lining material for bearings. It melts at a temperature of 288C (550F) or less. In a liquid state, it fills all cracks, voids and irregularities in a casting, giving a smooth surface to match the shaft surface.

A

Babbitt

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40
Q

____ can be used in badly worn bearing housings

A

Babbitt

41
Q

____ based babbitts are the hardest and toughest

A

Tin

42
Q

tin based babbitt with very high tin content is sometimes called ____ babbitt. Used in heavy service and extreme pressures

A

nickel

43
Q

Introducing a small percentage of ___ to a tin based babbitt gives a slightly softer material

A

lead

44
Q

____ based babbitt are cheaper and used for light loads at low speeds

A

Lead based babbitt.

Note: this is when lead replaces the majority of the tin. up to 10% tin and 75% lead

45
Q

When pouring babbitt, 275C-285C (495F-545F) is:

A

Melting point

46
Q

When pouring babbitt, 343C-371C (650F-700F) is:

A

Pour Point

47
Q

When pouring babbitt, 25C-28C (40F-50F) is

A

complete solidification point

48
Q

If babbitt is overheated, the ____ _____ of the material is greatly reduced

A

Service life

49
Q

Babbitt is held in position in a bearing casting by ___ which are grooves or slots in the casting

A

Keys

Note: Any bearing liner to be re-babbitted must have the keys cleaned out

50
Q

A ____ or dummy shaft is used to shape and size bearings

A

Mandrel

Note: must be several inches longer than the widest bearing to be poured

51
Q

A mandrel with side pieces helps you to:

A

quickly center the mandrel in the bearing housing

52
Q

Poured babbitt is held in position with a ring held in place by a backing of:

A

babbitt putty

53
Q

pouring babbitt can be ______ and is usually done by a designated millwright in the plant

A

dangerous

54
Q

When you pour babbitt into a bearing and mandrel assembly, make sure the assembly has been heated to 94C (200F) first to remove any free water or surface moisture. This is because:

A

Free water causes a “blow back” or explosion

55
Q

Preparation for babbitting is critical, the vertical and horizontal shaft positions are _____ ____.

A

Most important

56
Q

when a thin skin of babbitt must be firmly attached to a metallic backing, a ____ process is used. Similar to brazing a brass coating.

A

Tinning

57
Q

Any bearing (regardless of shape or material) must prepared carefully. You must check: (4)

A
  • Surface Finish (area of contact)
  • Running Clearance
  • Lubrication Entry
  • Grooves (for distributing lubrication)
58
Q

Hand tools, such as scrapers, used for fitting bearings may be a commercial product or:

A

Hand made tool

59
Q

After the bearing has been babbitted, the corners of the bottom half must be ____ to keep the shaft from binding

A

relieved

60
Q

With babbitt, the top edge of the bearing must be _____ almost to the corners. This channels the lubricant to the shaft.

A

Chamfered

Note: Chamfer is often greater for grease than with oil

61
Q

With babbitt, always cut grooves into the ____ section of the bearing

A

unloaded

62
Q

A one piece or solid bearing used in an inverted position may need to be lubricated through the ____ of the bearing

A

Base

63
Q

After the chamfers and/or oil grooves are cut into the load bearing surfaces, check the bearing for ______. to do this, lightly coat a mandrel in mechanics bluing and rotate it in the bearing.

A

contact

64
Q

When a bearing is assembled, there must be a small amount of ____ between the shaft and bearing cap.

A

Clearance

65
Q

Shims are made from material that will not _____

A

Compress

66
Q

shims are made from materials that are not affected by _______

A

oil

67
Q

These are 3 materials you can make shims from: (3)

A
  • Sheet packing
  • Tin plate
  • Brass shim stock
68
Q

What is the advantage and disadvantage of slip-in shims?

A

Advantage: Cap doesn’t need to be fully disassembled for installation

Disadvantage: Can lose the shims easier

69
Q

The amount of clearance set into a friction bearing depends upon ______ and company policy.

A

Machine design

70
Q

Some machines with a constant load toward the base of the bearing do not have a ______

A

fitted cap

Note: Cap merely keeps out foreign material and supplies lubricant

71
Q

As a general rule, with constant one direction load and rotation, bearing clearance can be from ____ to ____

A

Medium to loose

72
Q

As a general rule, with reversing rotation and fluctuating loads, bearing clearance can be from _____ to _____

A

medium to tight

73
Q

as a general rule, with reciprocating action, bearing clearance must be _____

A

tight

74
Q

What are three ways you can check bearing clearance on a shaft? (3)

A
  • Feeler gauge
  • Plastigage/lead wire
  • Dial indicators
75
Q

____ are two piece liners installed in a bearing housing. They are usually held in position by pins, dowels, screws, special bearing designs, compression, or combinations of those.

A

Shells

76
Q

When shells are first installed, they frequently extend past the face of the bearing by a small amount. This is known as the _____

A

Crush or Crush allowance

77
Q

With bearing shells, when the cap and other shell is installed and fasteners are torqued to the correct tension, the shells are forced into ____ ____ with the housing

A

Full Contact

78
Q

Shells can be installed and used in two cases: (2)

A
  • No adjustment for wear

- Wear adjustment is obtained by shims

79
Q

One advantage of shell liners is that they may be _____ by taking the weight of the shaft off the liner.

A

removed

80
Q

_____ are one piece liners and can be made from any of the common bearing materials.

A

Bushings

81
Q

With a bushing, fit and clearance are usually set by the dimensions machined into the housing and bushing. It is held in position by: (3)

A
  • Press fit
  • Press fit and dowels
  • Dowels with clamping action between cap and base
82
Q

Small bushings can be ____ to bring the bore to the correct diameter.

A

Reamed

83
Q

Larger diameter bushings sometimes require _____ or scraping

A

Honing

84
Q

If the bushing is supplied with an oil hole, you must align it to the supply line when pressing in the bushing. With some bushings, the oil line must be _____ after installation.

A

Drilled.

Note: Should be scraped to remove high spots caused by drilling

85
Q

When a bushing is worn it must be replaced as there is no:

A

Adjustment for clearance

86
Q

Friction bearings are usually considered radial load bearings with limited ____ capacity.

A

Thrust

Note: Thrust (axial force) is usually controlled with other components

87
Q

The thrust in a plain bearing is controlled by a shaft collar fastened to the shaft, or by a thrust washer backed by a hub. Such a design is good for: (3)

A
  • Low speeds
  • light to medium intermittent thrust loading
  • simple lubrication
88
Q

Thrust of a shaft is controlled by the shaft shoulder and a collar that adjusts the amount of:

A

End float

Note: If the shaft shoulder is not high enough, you may add a collar or other machined component to contact the bearing surface. Good for high speed applications.

89
Q

End float is:

A

The amount a shaft moves axially in a bearing

90
Q

The liner material that covers the ends of bearings may be made of any of the following materials: (3)

A
  • solid babbitt poured in the bearing
  • shells made of brass or bronze
  • brass shell with a tinned babbitt wear face
91
Q

Some bearings are designed to carry both radial and thrust forces without the use of other components. Such setups require:

A

shaft and bearing liner material to have matching parallel grooves

Note: no adjustment for end float, and lubrication can be a problem

92
Q

This bearing is a special thrust bearing designed to take high speeds and heavy loads:

A

Kingsbury thrust bearing

93
Q

The basic design of a kingsbury thrust bearing consists of: (2)

A
  • Revolving ring with flat contact surface
  • Stationary ring with a number of flat contact surfaces of a low friction material.

Note: material of stationary ring can either be brass, bronze, or a tinned on high capacity babbit on a brass backing

94
Q

With a kingsbury thrust bearing, the lubricant is supplied to the center of the bearing and distributed via:

A

Centrifugal force

95
Q

What two styles do kingsbury bearings come in: (2)

A
  • Fixed pad

- Floating or tilting pad

96
Q

This bearing is a positioning device or guide for linear motion.

A

Guide bearing

Normally has thin layer of bearing material on its surface and operates with lubrication

97
Q

This bearing is a split journal bearing mostly used for high peripheral speeds and shaft stabilization. The shoes are machined cylindrically to fit freely in grooves in a retaining ring.

A

Pivoted shoe bearing

Note: This bearing operates similar to the flat, tilting pad, kingsbury bearing

98
Q

The surfaces of the shoes and rings on a pivoted shoe bearing are _____ _____ and low friction. The bearing is dowelled so the halves can only be joined one way

A

corrosion resistant

99
Q

On a pivoted shoe bearing, each shoe has its own oil inlet, which helps to: (2)

A
  • Lower operating temperature

- Keep it uniform

Industrial Mechanic 2nd Block, Harmonized (28 decks)

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