Chapter 13: Rolling Element Bearings

1
Chapter 13 Rolling Element Bearings
Since there is no model in nature for guiding
wheels on axles or axle journals, man faced a
great task in designing bearings - a task which
has not lost its importance and attraction to
this day.
2
Radial Ball Bearings
Table 13.1 Characteristics of representative
radial ball bearings.
3
Angular-Contact Ball Bearings
Table 13.2 Characteristics of representative
angular-contact ball bearings.
4
Thrust Ball Bearings
Table 13.1 Characteristics of representative
thrust ball bearings.
5
Cylindrical Roller Bearings
Table 13.1 Characteristics of representative
cylindrical roller bearings.
6
Spherical Roller Bearings
Table 13.5 Characteristics of representative
spherical roller bearings.
7
Radial Single-Row Ball Bearings
Figure 13.1 (a) Cross section through radial
single-row ball bearings (b) examples of radial
single-row ball bearings.
8
Race Conformity and Axial Shift
Figure 13.2 Cross section of ball and outer
race, showing race conformity.
Figure 13.1 Cross section of radial bearing,
showing ball-race contact due to axial shift of
inner and outer races. (a) Initial position (b)
shifted position.
9
Free Contact Angle and Endplay
Figure 13.4 (a) Free contact angle and endplay
as function of cd/2d for four values of total
conformity ratio.
10
Ball Bearing
Figure 13.5 Shoulder height in a ball bearing.
Figure 13.6 Cross section of ball bearing.
11
Spherical, Cylindrical and Toroidal Bearings
Figure 13.7 (a) Spherical roller (fully crowned)
and (b) cylindrical roller (c) section of
toroidal roller bearing.
12
Spherical Roller Bearing
Figure 13.8 Geometry of spherical roller bearing.
Figure 13.9 Schematic diagram of spherical
roller bearing, showing diametral play and
endplay.
13
Contact Angle and Angular Velocity of Ball
Figure 13.10 Contact angles in ball bearing at
appreciable speeds.
Figure 13.11 Angular velocities of ball
14
Ball Spin Orientations
Figure 13.12 Ball-spin orientations for (a)
outer-race and (b) inner race control.
15
Tapered Roller Bearing
Figure 13.13 Tapered-roller bearing. (a)
Tapered-roller bearing with outer race removed to
show rolling elements (b) simplified geometry
for tapered-roller bearing.
16
Radially Loaded Rolling Element Bearing
Figure 13.14 Radial loaded rolling-element
bearing. (a) Concentric arrangement (b) initial
contact (c) interference.
17
Contact Ellipse and Angular Contact Ball Bearing
Figure 13.15 Contact ellipse in bearing race
under load.
Figure 13.16 Angular-contact ball bearing under
thrust load.
18
Back-to-Back Arrangement
Figure 13.17 Angular-contact bearings in
back-to-back arrangement, shown (a) individually
as manufactured and (b) as mounted with preload.
19
Load-Deflection Curve
Figure 13.18 Thrust load-axial deflection curve
for typical ball bearing.
20
Bearing Ratings
Table 13.1 Single-row, deep-groove ball bearings.
21
Bearing Ratings
Table 13.7 Single-row cylindrical roller
bearings.
22
Combined Load
Table 13.8 Radial factor X0 and thrust factor Y0
for statically stressed radial bearings.
Figure 13.19 Combined load acting on radial
deep-groove ball bearing.
23
Fatigue Spall
Figure 13.20 Typical fatigue spall (a) Spall on
tapered roller bearing (b) detail of fatigue
spall.
24
Fatigue Failure
Figure 13.22 Representation of m similar
stressed volumes.
Figure 13.21 Distribution of bearing fatigue
failures.
25
Bearing Fatigue Failures
Figure 13.23 Typical Weibull plot of bearing
fatigue failures.
26
Capacity Formulas
Table 13.9 Capacity formulas for rectangular and
elliptical conjunctions for radial and angular
bearings.
27
Radial and Thrust Factor for Thrust Bearings
Table 13.10 Radial factor X and thrust factor Y
for thrust bearings.
28
Material Factors
Table 13.11 Material factors for
through-hardened bearing materials.
29
Lubrication and Bearing Life
Figure 13.24 Group fatigue life L10 as a
function of dimensionless film parameter.
Figure 13.25 Lubrication factor as a function of
dimensionless film parameter.