Anti Friction Bearings Flashcards
1
Q
Three advantages of anti friction bearings are: (3)
A
- Versatility
- Low friction
- Can be packed to avoid frequent lubrication
2
Q
The basic parts of an anti friction bearing are: (3)
A
- Two hardened steel rings (races)
- Hardened balls or rollers (rolling elements)
- separator
3
Q
If there is no inner ring, the bearings fit directly on the:
A
Hardened shaft
4
Q
Bearings may have other parts, such as a snap ring to set:
A
axial location
5
Q
Rolling elements are classified into these 3 basic styles: (3)
A
- Ball
- Roller
- Needle
6
Q
Roller bearings can be sub-divided into these 3 styles: (3)
A
- Cylindrical
- Tapered
- Spherical
7
Q
Ball bearings can be used as a guide for axial shaft measurement using:
A
recirculating ball bushings
8
Q
Many bearings use shields and seals to prevent:
A
Unwanted material from entering the housing
9
Q
Regarding seals, you would use this type of bearing when lubricant is expected to work through the bearing from one side to the other
A
Open bearing
10
Q
Regarding seals, you would use this type of bearing when you want solids kept out but not fluids
A
Shielded bearing
11
Q
Regarding seals, you would use this type of bearing when you want both solids and fluids kept out
A
sealed bearing
12
Q
Regarding seals, you would use this type of bearing when conditions are very dirty and abrasive
A
Shielded and sealed bearing
13
Q
Ball bearings have a low to ____ load capacity
A
medium
14
Q
roller bearings usually have a low to ____ load capacity
A
high
15
Q
What are the three types of loads that can be applied to anti friction bearings? (3)
A
- Radial load
- Thrust (axial) load
- Combination radial thrust load (aka angular load)
16
Q
Ball bearings are generally suited to high speed applications, up to ______ RPM
A
40, 000 RPM
17
Q
Roller bearings are generally suited to lower speed applications, up to _____ RPM
A
20, 000 RPM
Normal range is 2000-20 000 RPM
18
Q
As the load capacity of a bearing increases, the bore stays the same, but:
A
The outer diameter increases and the width and thickness of the rings increases
19
Q
Regarding bearing service weight, 00 refers to:
A
Ultra light
20
Q
Regarding bearing service weight, 100 refers to:
A
Extra light
21
Q
Regarding bearing service weight, 200 refers to:
A
Light
22
Q
Regarding bearing service weight, 300 refers to:
A
Medium
23
Q
Regarding bearing service weight, 400 refers to:
A
Heavy duty
24
Q
Roller bearings may have either a _____ or _____ bore
A
straight or tapered
25
The bearing bore size is indicated by the _______ digits of the bearing number
last two
26
From 20mm to 480mm, the bearing bore diameter is is found by multiplying the last two digits of the bearing number by:
5
27
Above 480mm, the bearing bore diameter is
directly included in the bearing number
28
a non separable bearing is one that:
cannot be separated easily
29
a separable bearing is one that:
can easily be taken apart
30
non aligning bearings are used in machines where:
bearings are held in alignment by the bores in the housing
31
self aligning bearings may be internal or external. In an internal self aligning bearing, the inside of the outer ring is:
concave
32
self aligning bearings may be internal or external. In an external self aligning bearing, the outside of the outer ring is:
convex
33
Most bearing codes give 3 pieces of information: (3)
- Type of rolling element
- Service weight
- Diameter of bore in mm
34
in most cases, the orientation of a bearing won't matter, but it's good practice to face the bearing code numbers towards the end of the shaft because:
It's easier and quicker to identify the bearing
35
On a bearing code, the letter K identifies:
A tapered bore, 1:12 taper
36
Initial clearance is the:
Clearance in a bearing before it is installed on the shaft
37
Installed clearance is the clearance left in the bearing after installing it, or:
Or the clearance left in a taper bore bearing that has been forced up the taper
38
Running clearance is the:
Clearance left in a bearing when the machine is at operating temperature and has lubricant supplied
39
Bearings may have one of two fits: (2)
- Push fit
| - Interference fit
40
Be careful when using an emery cloth to improve the shaft surface, be careful to:
Not remove interference deliberately machined in the shaft
41
When installing a bearing, after checking a shaft, wipe it clean and coat it with a light oil. With a press fit, you may need to use a:
Anti seize compound
42
Push fit means:
Bearing is installed by hand without mechanical aids
Used when the bearing is held in place by mechanical aids, such as snap rings
43
___ is the very slow rotation of a push fit bearing race. One rotation of the ring is equal to several million revolutions of the rest of the bearing.
Creep
44
Creep changes the contact area on a raceway and:
Extends the life of the bearing
45
The amount of interference in the shaft and bearing ring is exactly equal to the______ in the bearings after installation
Clearance reduction
46
To achieve interference fits, bearings can be installed using: (2)
- Press or shrink fits
| - Tapered adapter sleeve
47
In regards to bearing fits, the usual bearing installation has:
One ring interference fit, one ring push fit
48
On a straight bore bearing, which bearing ring has the press fit?
Rotating ring
Non rotating is a push fit
49
Press fits are common on small bore bearings. To press fit a bearing, use a ____ to distribute force evenly
tube
50
When pressing a bearing onto a shaft, ensure it is square to the shaft, and apply a light coat of:
oil to reduce friction
51
As you press a bearing onto a shaft, rotate the outer ring by hand to check:
Clearance. If clearance is lost, do not press the bearing the rest of the way
52
When pressing a shaft through a bearing, ensure your support blocks touch:
Both the inner and outer races, but most importantly, the inner race,
53
When heating a bearing, it is usually heated to ____ °C above ambient temperatures
45-50C
Note: No higher than 120C
54
To chill a bearing, you can use: (2)
- Liquid air
| - Dry ice and alcohol
55
To heat a bearing, some common methods are to use: (4)
- Heat lamps
- Oven
- Induction heater
- Oil bath
56
____ method of heating a bearing is slow and can be used for small bearings.
heat lamp
57
____ method of heating a bearing is relatively safe, as the temperature can be controlled
Oven
58
____ method of heating a bearing is quick and quiet. Temperatures are monitored with a wax crayon or by measuring the bore
Induction heater
59
When using _____ method of heating a bearing, it is important to remember to keep the bearings suspended with wire
oil bath
60
When installing a hot bearing on a shaft, move it:
quickly to its final position
61
Press or shrink fitting will reduce the:
Internal clearance on the bearing.
62
A replacement bearing such as a tapered roller or angular contact bearing has the end float controlled by:
shims
63
An outer ring can be installed in either a bored (solid, one piece) housing or a:
split housing
64
Positive keeping is to:
use a device to hold position
65
In tapered roller bearings, the inner race is called the:
cone
66
In tapered roller bearings, the outer race is called the:
Cup
67
The end caps on a bearing can be used for:
positive positioning (axial)
note: can be with or without shims
68
To prevent end float:
One bearing on any assembly should be fixed axially in the housing
Note: called the held or fixed bearing
69
It is generally better to locate the fixed bearing on the:
drive end of the shaft
70
A bearing that is not fixed axially is called a:
Free or floating bearing
71
Having floating bearings allows:
the shaft to expand and contract
72
The floating bearing is usually where within the pillow block?
center, never up against a shoulder
73
Tapered roller and angular contact bearings are mounted so the end float of a shaft between two bearings is:
held to a required minimum
74
Thrust adjustment on a bearing may be made in two ways. When the outer race, or cup, is fixed in the housing:
adjust the inner race or cone
75
Thrust adjustment on a bearing may be made in two ways. When the inner race, or cone, is fixed on the shaft:
adjust the outer race or cup
76
In most applications, the outer race is adjusted by means of:
end cover and shims
77
Angular contact bearings are bought and installed as a matched pair. What are the three basic arrangements? (3)
- Back to back
- Face to face
- Tandem
Note: which one you use depends on load, speed, direction and the amount of thrust
78
The use of a tapered sleeve adapter allows you to:
mount bearings at any place along a standard shaft
79
When tapered adapter mountings are used, take care that the bearing is not tight internally, because:
the clearance will be eliminated
80
What is being described?
- Swivel the outer race while tightening
- you will feel light drag when clearance is reduced
- stop tightening at this point and lock in place
mounting ball bearings with a tapered adapter sleeve
Note: the general procedure
81
Dismounting a bearing hydraulically gives a:
Abrupt release
82
When installing tapered bore spherical roller bearings, the most practical method for checking clearance is to:
use feeler gauges
83
When mounting tapered bore bearings, it can be helpful to oil:
Outside and threads of the sleeve
84
You can assemble smaller tapered bore bearings with the tab washer in position, but it is not recommended for larger bore bearings because:
you could shear the tab
85
when mounting tapered bore spherical roller bearings, you should tighten the adapter nut with a spanner wrench until it is snug. Drive against the nut with a hammer and soft steel bar, tighten, check for clearance, repeat drive/tighten, until :
final clearance is reached.
86
For standard clearance, spherical roller bearings where no tables are available, a rule of thumb is to reduce the initial clearance by roughly:
50%
note: another rule of thumb is to convert the last two digits of a bearing number into thousandths of an inch and reduce the bearing clearance by that much.
87
The best way to pull off a bearing with a minimum amount of damage to the bearing or shaft is with a: (2)
- press
| - pullers
88
When pressing a bearing off a shaft, ensure that:
no load goes through the rolling elements. Press on inner race.
89
When removing a bearing from a shaft, if you need to pull on the outer race, you should:
Guard the outer ring to prevent injury from debris if the bearing explodes/fractures
Note: especially important when hydraulically pulling
90
You can remove bearing cups from a housing with a:
Cup puller aka Inside puller
91
The big differences in a withdrawal sleeve vs an adapter sleeve is the withdrawal sleeve: (3)
- Used in a solid bored housing
- Sleeve slides under the bearing
- Bearing is held by a shoulder against inner ring
92
When installing a withdrawal sleeve, the installation order is bearing then sleeve. When installing an adapter sleeve, the order is:
Sleeve then bearing
93
Both the adapter sleeve and the withdrawal sleeve use the same routines to check the:
Initial clearance
94
The tool used to remove a tapered withdrawal sleeve is called a:
Withdrawal nut
95
Bearing cups are frequently set in seats with no room to use a set of pullers. In such a case, the cup can be removed by:
Welding a bead on the face of the raceway. This will shrink the race as it cools
96
Hydraulic dismounting (removal) uses the force developed by the oil or grease pressure to:
expand the inner ring of the bearing
97
For hydraulic dismounting, oil injection can be done with: (2)
- Grease gun (capable of developing 1000PSI)
| - Hand operated pump for a portable jack (using SAE 40 or heavier oil)
98
When hydraulically dismounting a bearing from a tapered sleeve, what should you do to ensure safety?
Leave the locknut on the threads and keep it close to the bearing. The press fit will be immediately and abruptly released.
99
Pillow blocks come in two main groups: (2)
- One piece
| - Split
100
One piece pillow block housings are pre assembled. The unit is slipped over a smooth shaft and bolted into position. Common designs are: (3)
- Single groove ball bearings
- double taper roller bearings
- spherical or concave rollers
Note: these bearings are externally self aligning. Shape of the outer ring rocks/pivots in the housing.
101
Two common methods of securing a one piece bearing housing to a shaft are: (2)
- Eccentric collar
| - two set screws
102
A pillow block is mounted with its base:
Parallel to the shaft
103
When mounting pillow blocks with one piece housings, tighten them on the base before:
locking the inner ring in position on the shaft.
Note: allows the bearing to align to the shaft
104
A flange bearing has its base at:
90° to the shaft
105
The inner/outer rings and rolling elements of flange bearings are easily replaceable and supplied as one unit called a:
cartridge
106
One common type of needle bearing has no separators or inner ring only an outer ring and rolling elements. To keep the the needles in place before mounting, the bearing is fitted with a:
temporary sleeve
Note: it is possible to coat smaller roller bearings in grease so they stay in position while installing
107
Thrust bearings, because of centrifugal force, are limited in:
The speed they can be used at
108
Tread bearings with one side shielded like:
bearings without a shield
109
Do not wash bearings with seals on both sides, instead:
wipe them with a clean rag
Note: to prevent dirt from working inside
110
When washing a bearing in solvent, use two washes. Do the second wash in:
clean solvent
111
When using an air hose to clean a bearing, don't:
spin the bearing.
112
Some solvents remove all traces of lube, leaving a dry bearing, which can do what when checking for wear?
give false readings
113
When storing bearings, coat them lightly in oil. Store them in a special, :
acid free bearing wrapper (oil impregnated paper)
114
Store bearings in a clean, dry place until needed, away from:
vibrations
115
What are 3 symptoms of bearing failure: (3)
- Temperature rise
- Increased vibration
- Unusual noise
116
The most common cause of anti-friction bearing failure is:
contamination
117
Fill a housing 1/3 to 1/2 with grease. For oil lubrication, fill the case up to:
halfway up the lowest rolling element
118
Cooper bearings are:
Split bearings, used where bearing location is not easily accessible.
