Angled Bearing Load Life Analysis

Angled bearings are often used in pairs to support both axial directions.

• Deep groove ball bearings can still be used when $F_a$ is comparable to $F_r$, but they are not advised if $F_a$ is more than 10-30% of $C_0$ (static load rating) or $F_a\gg F_r$ (axial load is excessively larger than radial one)

They are used for combined radial and (large) axial loads. These bearings require different load analysis due to the “effective load center” $a$, and the “induced axial load”, given by

$$F_{ai}=\frac{0.6}{Y}{F}_r$$

where $Y$ is the axial load factor.

Let’s say that we have pair of angular contact ball bearings in B2B (or O) configuration. $F_{ae}$ is an external axial load.

Equivalent loads are computed based on the effective axial loads.

• If $F_{ae}+\frac{0.6}{Y_{II}}{F}_{rII}\ge \frac{0.6}{Y_I{F}_{r}I}$, we have:

$$\{\begin{array}{l}{P}_I=X{F}_{rI}+Y_I\underset{=F_{aI}}{\underbrace{\left(F_{ae}+\frac{0.6}{Y_{II}}{F}_{rII}\right)}}\\ P_{II}=F_{rII}(\text{i.e. }{F}_{aII}=0)\end{array}$$

• Otherwise:

$$\{\begin{array}{l}{P}_I=F_{rI}(\text{i.e. }{F}_{aII}=0)\\ P_{II}=X{F}_{rII}+Y_{II}\underset{=F_{aII}}{\underbrace{\left(\frac{0.6}{Y_I}{F}_{rI}-F_{ae}\right)}}\end{array}$$

Note that:

• $\frac{0.6}{Y_{II}}{F}_{rII}$ is the axial load induced by $F_{rII}(\to )$
• $\frac{0.6}{Y_I}{F}_{rI}$ is the axial load induced by $F_{rI}(\leftarrow )$

Example