Most popular types of ball bearings are single-row radial also known as “deep-groove” and single-row angular contact bearing.
Both bearings are capable of taking combined radial and thrust loads, but radial bearing is not intended for pure thrust load, while for angular bearing thrust component can be large.
The performance of ball bearings is the function of many variables like bearing material, characteristic of application... To estimate the suitability of a particular bearing two factors are taken into consideration:
- bearing fatigue life
- ability to withstand static load.
For bearing fatigue life we can use ball bearing Rated life (L10).
Bearing rated life is measured in millions of revolution that 90% of apparently identical bearings under same operating conditions will complete or surpass. Rated life can be calculated as
L10=(Cor/Por)3
where Cor-basic dynamic load ratings (N), listed in the bearing table for each individual bearing
Por-equivalent dynamic radial load (N)
Por = X*Fr + Y*Fa
where Fr - applied radial load (N)
Fa - applied axial load (N)
X - radial load factor given in table 1.
Y - axial load factor given in table 1.
Table11.
Contact
Angle ά
|
Fa/Co
|
e
|
Fa/Fr ≤ e
|
Fa/Fr > e
|
| X |
Y |
X |
Y |
0°
|
0.014 |
0.19 |
1 |
0 |
0.56 |
1.30 |
| 0.018 |
0.11 |
1.99 |
| 0.056 |
0.16 |
1.71 |
| 0.084 |
0.18 |
1.56 |
| 0.11 |
0.3 |
1.45 |
| 0.17 |
0.34 |
1.31 |
| 0.18 |
0.38 |
1.15 |
| 0.41 |
0.41 |
1.04 |
| 0.56 |
0.44 |
1 |
| 30° |
… |
0.80 |
1 |
0 |
0.39 |
0.76 |
Size of static equivalent load Po (N) under combine thrust and radial loads is
Po = Xo* Fr + Yo* Fa
or
Po = Fr
which ever is greater.
where Fr - applied radial load (N)
Fa - applied axial load (N)
Xo - radial load factor given in table 1.
Yo - axial load factor given in table 1.
Table11.
Contact Angle ά
|
Xo
|
Yo
|
0°
|
0.6
|
0.5
|
30°
|
0.5
|
0.33
|
1-(16th Edition Machinery’s Handbook; Eric Oberg, Franklin D. Jones, Holbrook l. Horton, and Henry H. Ryffell; 1000 Industrial Press INC, New York)
Generally the permitted static equivalent load is limited by the basic static load (Cor) rating listed in the bearing table for each individual bearing
*Note that calculated values are for ideal operating conditions and that no correction factors (material, operating conditions) apply. Use good engineering practice when calculating bearing life for particular application.
Radial and load factors may slightly very depending on bearing manufacturers.
For Deep grove ball bearings use contact angle 0°.
For Misumi angular bearings use contact angle 30°.