Alb Mod Bearing Seals and Pillow Blocks

Question 1

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:

Answer 1

External seal

Question 2

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

Answer 2

Materials and styles

Question 3

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:

Answer 3

Integral seal

Question 4

An integral seal has the advantage of being

Answer 4

Cheaper and more compact

Question 5

Rubbing seals are also called:

Answer 5

Contact seals

Question 6

Non rubbing seals are also called:

Answer 6

non-contact seals

Question 7

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

Answer 7

• Can retain grease as well as oil

- Provide a positive seal against moisture and fine contamination

Question 8

Why does a rubbing seal have a lower speed limit?

Answer 8

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

Question 9

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

Answer 9

lip

Question 10

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

Answer 10

• Garter spring

- Light interference fit between seal and shaft

Question 11

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

Answer 11

• Whirling lubricant presses on inside of lip

- Gas or liquid pressure presses on inside of lip

Question 12

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

Answer 12

4 Meters/second (13.12 ft/second)

Question 13

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

Answer 13

double

0.8 microns

Question 14

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

Answer 14

-40C to 200C

Question 15

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

Answer 15

• 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

Question 16

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

Answer 16

Fails very quickly

Question 17

When installing a lip seal, ensure the bore is:

Answer 17

Clean, free of burrs and deposits

Question 18

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

Answer 18

Spiral and longitudinal

Note: they provide a leak path through the seal

Question 19

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

Answer 19

Thimble

Question 20

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

Answer 20

V-ring seal

Question 21

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.

Answer 21

15 M/s (49.2 F/s)

Question 22

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.

Answer 22

V-ring seal

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

Question 23

___ 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.

Answer 23

Felt seals

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

Question 24

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

Answer 24

mechanical seal

Note: most expensive bearing seal.

Question 25

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

Answer 25

Integral rubbing seals

Question 26

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

Answer 26

- 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

Question 27

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

Answer 27

positive seal

Question 28

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

Answer 28

- Spiral groove | - Flinger

Question 29

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

Answer 29

- Narrowness of the gaps - Number of gaps Note: seal is better with more, smaller gaps

Question 30

External non-rubbing seals are mounted on the:

Answer 30

Housing

Question 31

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.

Answer 31

Smooth Gap Seal

Question 32

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

Answer 32

Radial Labyrinth seals

Question 33

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

Answer 33

Axial labyrinth seal

Question 34

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

Answer 34

Combination axial radial seal

Question 35

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

Answer 35

Sealing washer set

Question 36

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

Answer 36

Increasing the number of washer sets

Question 37

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

Answer 37

rotating discs

Question 38

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

Answer 38

Flinger rings Note: oil returned via a return duct

Question 39

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

Answer 39

Labyrinth seal

Question 40

Integral non-rubbing seals are commonly referred to as _____

Answer 40

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

Question 41

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

Answer 41

does not quite touch the inner ring

Question 42

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

Answer 42

Shield or integral non rubbing seal

Question 43

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

Answer 43

stops Should also be installed if there is substantial axial loading

Question 44

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.

Answer 44

two or four cap bolts

Question 45

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

Answer 45

one third to two thirds

Question 46

Horizontally split Pillow block bearings are intended mainly for _____ loads

Answer 46

radial

Question 47

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

Answer 47

the same as the bearing capacity

Question 48

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

Answer 48

- double row spherical roller | - double row self aligning ball

Question 49

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

Answer 49

- assist in installation | - assist in lubrication

Question 50

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

Answer 50

help with properly aligning the cap

Question 51

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

Answer 51

- clearance in the bearing seat | - extra room axially for movement

Question 52

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

Answer 52

locating ring

Question 53

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

Answer 53

The side with the locknut

Question 54

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

Answer 54

Cast iron

Question 55

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

Answer 55

cast steel

Question 56

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

Answer 56

No, they are made in matched sets

Question 57

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

Answer 57

sufficient pre load

Question 58

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

Answer 58

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%

Question 59

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

Answer 59

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

Question 60

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

Answer 60

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

Question 61

Locating rings can also be called:

Answer 61

stabilizing rings or fixing rings

Question 62

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

Answer 62

a free or a floating bearing

Question 63

It is important to have floating bearings to allow:

Answer 63

axial expansion of the shaft

Question 64

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

Answer 64

Fixed bearing

Question 65

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

Answer 65

locating ring(s)

Question 66

Where do you normally have the fixed bearing located?

Answer 66

Drive end of the shaft

Question 67

Different models of pillow blocks are made to accept _____ seals

Answer 67

Any external seals

Question 68

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

Answer 68

- Diameter of the opening around the shaft | - groove dimensions in the housing

Question 69

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

Answer 69

a more efficient seal

Question 70

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

Answer 70

Bearing first, then seal

Question 71

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.

Answer 71

Unit pillow blocks

Question 72

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:

Answer 72

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

Question 73

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

Answer 73

90°

Question 74

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

Answer 74

- Babbitt - Aluminum - Phosphorous bronze

Question 75

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

Answer 75

- Nylon - Teflon - Phenol Laminates

Question 76

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

Answer 76

- Angle - V - Gib (strongest for side loads) - Solid plain

Question 77

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

Answer 77

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