Question

A ball bearing is subjected to a radial load of 2500 N and an axial force of 1000 N. The catalogue gives the following data: Radial factor = 0.4, Axial thrust factor = 1.5, Static load rating = 10000 N, Dynamic load Rating = 7500 N. The bearing life in millions of revolutions is

• A. 8
• B. 9
• C. 1
• D. 27

Answer 1

The correct option is D 27

$\text{Fr = 2500 N, Fa = 1000 N}$

$\text{X = 0.4, Y = 1.5, S = 10000 N}$

We know that equivalent load on bearing is given by

$P_e=X{F}_r+Y{F}_a$

$P_e=0.4\times 2500+1.5\times 1000=2500N$

$L_{90}={\left(\frac{C}{P_e}\right)}^3\equiv {\left(\frac{7500}{2500}\right)}^3\text{million revolutions.}$

$L_{90}=3^3=27\text{million revolutions.}$