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Industrial Mechanic 2nd Block, Harmonized > Alb Mod Bearing Seals and Pillow Blocks > Flashcards

Alb Mod Bearing Seals and Pillow Blocks Flashcards

1
Q

There are two basic ways to seal a bearing. One way is to install a seal on the bearing housing. This would be described as a:

A

External seal

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2
Q

An external seal has the advantage of offering a wide selection of:

A

Materials and styles

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3
Q

There are two basic ways to seal a bearing. One way is to install a seal on the bearing itself. This would be described as a:

A

Integral seal

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4
Q

An integral seal has the advantage of being

A

Cheaper and more compact

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5
Q

Rubbing seals are also called:

A

Contact seals

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6
Q

Non rubbing seals are also called:

A

non-contact seals

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7
Q

Since rubbing seals contact the sealing surface, they have two main advantages over non rubbing seals. What are they? (2)

A
  • Can retain grease as well as oil

- Provide a positive seal against moisture and fine contamination

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8
Q

Why does a rubbing seal have a lower speed limit?

A

The friction generated by the seal rubbing on the sealing surface limits speed

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9
Q

The ___ seal makes a seal by pressing the seal lip against the seal surface.

A

lip

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10
Q

With a lip seal, the light contact pressure before start up is provided by: (2)

A
  • Garter spring

- Light interference fit between seal and shaft

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11
Q

With a lip seal, the contact pressure may be increased after start up by: (2)

A
  • Whirling lubricant presses on inside of lip

- Gas or liquid pressure presses on inside of lip

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12
Q

The surface speed of a lip seal on an unhardened shaft is limited to:

A

4 Meters/second (13.12 ft/second)

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13
Q

Using a hardened shaft with a lip seal can ____ your speed limitations vs an unhardened shaft. Requires a hardness of rockwell C45 and a surface roughness of ___ microns

A

double

0.8 microns

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14
Q

The temperature range on a lip seal is limited to ___ C to ____ C

A

-40C to 200C

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15
Q

What are four notes you should keep in mind regarding the lip seals? (4)

A
  • Requires film of liquid to form seal
  • Requires finish free of burrs and scratches
  • Requires any marks from machining or polishing to be perpendicular to the shaft axis
  • Requires no contamination between lip and shaft
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16
Q

A lip seal is damaged easily upon installation. If damaged, it:

A

Fails very quickly

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17
Q

When installing a lip seal, ensure the bore is:

A

Clean, free of burrs and deposits

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18
Q

When polishing a lip seal surface on a shaft, avoid ____ and ____ scratches

A

Spiral and longitudinal

Note: they provide a leak path through the seal

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19
Q

You should install this on a shaft before installing the shaft in a lip seal. Helps prevent the lip from being damaged by the shaft shoulder

A

Thimble

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20
Q

This seal acts as a contact seal up to a surface speed of 12 meters/second. Above that, it requires a steel support ring.

A

V-ring seal

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21
Q

With a V ring seal, above ___ Meters/second the lip of the seal lifts off the seal surface, at this point the only sealing action is from a flinging effect.

A

15 M/s (49.2 F/s)

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22
Q

This seal can be used with grease or oil. It is fitted tightly to the shaft and exerts a light axial pressure against a smooth surface on the housing. Can tolerate a large amount of axial misalignment at low speeds.

A

V-ring seal

When mounted outside the housing, it can only retain grease and not oil

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23
Q

___ seals are very simple, and the cheapest seal. Mainly used for grease, they are classified as a low speed seal and don’t handle chemicals or temperatures over 100C.

A

Felt seals

Note: should be soaked in oil before installation to reduce friction and wear

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24
Q

This type of seal can handle low peripheral speeds, severe service conditions, wet and dirty environments and provides a leakproof retention of lubricants.

A

mechanical seal

Note: most expensive bearing seal.

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25
Q

this seal can keep out vapors and liquids, but is better for lower surface speeds. Are part of a bearing assembly

A

Integral rubbing seals

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26
Q

Because non rubbing seals have no contact with the sealing surface, they offer these advantages: (5)

A
  • No rubbing friction
  • No wear
  • Not as easily damaged
  • No speed limits
  • Can run at higher temperatures

Note: Adding grease into the gaps can further increase the sealing efficiency

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27
Q

The main disadvantage of non-contact seals is they do not provide a _______ and cannot retain oil, only grease

A

positive seal

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28
Q

Non-contact seals do not provide a positive seal, and cannot contain oil unless one of these two implements are used: (2)

A
  • Spiral groove

- Flinger

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29
Q

The effectiveness of all non-contact seal arrangements depends on the: (2)

A
  • Narrowness of the gaps
  • Number of gaps

Note: seal is better with more, smaller gaps

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30
Q

External non-rubbing seals are mounted on the:

A

Housing

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31
Q

This non-rubbing rubbing seal is the simplest and cheapest of the non-rubbing seals. Has a smooth gap at at the surface of the shaft, and is only effective in a dry, dust free environment for grease lubricated bearings.

A

Smooth Gap Seal

32
Q

This type of non-rubbing seal is used in split housings, and can only tolerate limited axial or radial shaft movements.

A

Radial Labyrinth seals

33
Q

This type of non-rubbing seal can be used in a one piece housing. Axial movement does not alter the widths of gaps, which allows the gaps to be made very small

A

Axial labyrinth seal

34
Q

This non-rubbing seal is more effective than using a radial or axial labyrinth seal.

A

Combination axial radial seal

35
Q

This non-rubbing seal uses pressed steel washers to provide the cheapest labyrinth seal.

A

Sealing washer set

36
Q

With a sealing washer set, the efficiency of the seal can be increased by:

A

Increasing the number of washer sets

37
Q

With sealing washer sets, ________ attached to the shaft acts as a deflector and increases the efficiency of the seal

A

rotating discs

38
Q

______ are attached to the shaft and rotate within a groove in the seal, returning oil to the housing.

A

Flinger rings

Note: oil returned via a return duct

39
Q

Flingers extend the use of the _____ seal to oil lubricated bearings

A

Labyrinth seal

40
Q

Integral non-rubbing seals are commonly referred to as _____

A

shields

Does not restrict max operating speed, is most commonly used on small bearings

41
Q

Shields consist of a thin metal cover that is attached to the outer ring of the bearing, but:

A

does not quite touch the inner ring

42
Q

This type of seal is factory pre lubed with grease, and cannot keep out liquids or vapors.

A

Shield or integral non rubbing seal

43
Q

If there is substantial radial loading 55-120° perpendicular from the shafts axial center, ____ should be installed to ensure the pillow block is not pulled out of alignment

A

stops

Should also be installed if there is substantial axial loading

44
Q

If the load is not vertically down from the shafts axial center, the capacity depends on the strength of the cap and whether ____ or ____ are used.

A

two or four cap bolts

45
Q

The load capacity of a horizontally split pillow block bearing is reduced by ____ to _____ at 55° as the angle increases or if the loading is axial

A

one third to two thirds

46
Q

Horizontally split Pillow block bearings are intended mainly for _____ loads

A

radial

47
Q

The load capacity of a radial, straight down load on a horizontally split pillow block bearing is:

A

the same as the bearing capacity

48
Q

The bearings most commonly housed in an anti friction pillow block bearing are: (2)

A
  • double row spherical roller

- double row self aligning ball

49
Q

On a horizontally spilt pillow block bearing, the cap is removeable to: (2)

A
  • assist in installation

- assist in lubrication

50
Q

A horizontally split pillow block bearing has dowel pins, which:

A

help with properly aligning the cap

51
Q

Horizontally split pillow block bearings housings have what two features which allow a bearing to float? (2)

A
  • clearance in the bearing seat

- extra room axially for movement

52
Q

What is used to hold a bearing in position axially in a horizontally split pillow block bearing?

A

locating ring

53
Q

If using only one locating ring, what side should the ring go on?

A

The side with the locknut

54
Q

What is the cheapest, but also weakest of the materials available for a pillow block bearing?

A

Cast iron

55
Q

Ductile iron has a higher load rating than a cast iron pillow block bearing, but ____ is normally used in the most severe service where there is heavy shock loading

A

cast steel

56
Q

Can you interchange the cap from one pillow block to another?

A

No, they are made in matched sets

57
Q

The cap bolts on a pillow block bearing must have ____ to remain tight through the cycles of loading and unloading

A

sufficient pre load

58
Q

The rule of thumb for grease fill on a pillow block is to fill _________ of the free space around the bearing.

A

one third to two thirds

Exception is made for so called “total fill” greases such as lithium soap water resistant grease which can be filled to 90%

59
Q

The important thing to remember when greasing a pillow block bearing is:

A

There should be enough free space for the grease to circulate and not cause heat build up

60
Q

For re-lubrication, the grease fitting should be located on the side of the cap:

A

opposite the retaining nut.

Note: this is to avoid having the grease fibers torn as the grease is injected over the notches in the retaining nut

61
Q

Locating rings can also be called:

A

stabilizing rings or fixing rings

62
Q

A bearing that is allowed to float axially could be called:

A

a free or a floating bearing

63
Q

It is important to have floating bearings to allow:

A

axial expansion of the shaft

64
Q

While floating bearings are important, it is also usually necessary to have one:

A

Fixed bearing

65
Q

What do you use to create a fixed bearing in a pillow block?

A

locating ring(s)

66
Q

Where do you normally have the fixed bearing located?

A

Drive end of the shaft

67
Q

Different models of pillow blocks are made to accept _____ seals

A

Any external seals

68
Q

What determines the type of seal that can be fitted to a pillow block? (2)

A
  • Diameter of the opening around the shaft

- groove dimensions in the housing

69
Q

A grease fitting is included with some labyrinth seals to allow the grooves to be filled with grease, which gives you:

A

a more efficient seal

70
Q

When greasing a bearing and a seal, the procedure is to grease what first?

A

Bearing first, then seal

71
Q

This type of pillow block is constructed in one piece, and it’s load capacity is not reduced by angular loads. Bearings can be swapped quickly and easily, while also being self aligning. The housing itself is cheap.

A

Unit pillow blocks

72
Q

With unit pillow block bearing inserts, an interference fit bearing can be operated at full load capacity. However, with the eccentric locking collar or set screws on a slip fit bearing, the load capacity is:

A

reduced

Those two methods force the shaft slightly off center resulting in vibration

73
Q

A flanged bearing housing has its base at ___ ° to the axis of the insert

A

90°

74
Q

What metallic bearing materials can be used in a plain pillow block bearing? (3)

A
  • Babbitt
  • Aluminum
  • Phosphorous bronze
75
Q

What non-metallic bearing materials can be used in a plain pillow block bearing? (3)

A
  • Nylon
  • Teflon
  • Phenol Laminates
76
Q

Other pillow block joint designs can increase the angular load capacity. These designs include: (4) and which is the strongest for side loads?

A
  • Angle
  • V
  • Gib (strongest for side loads)
  • Solid plain
77
Q

What is the disadvantage of a solid plain bearing pillow block?

A

Must be either installed on the end of a shaft, or needs components removed to slide onto the shaft.

Industrial Mechanic 2nd Block, Harmonized (28 decks)

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