Find the dynamic load-carrying capacity of a roller bearing if the shaft rotates at 1500 rpm, the radial load acting on the bearing is 6 kN and the expected life for 90% life of the bearing is 8100 hours.

Question

Question

This question was previously asked in

UPPSC AE Mechanical 2019 Official Paper I (Held on 13 Dec 2020)

Answer 1

Concept:

Load-life relationship:

The approximate rating of the service life of a ball or roller bearing is based on the given fundamental equation.

L10 = Rated bearing life (in million revolutions)

C = Dynamic load capacity.

P = Load acting in bearing.

k = 3 for ball bearing and k = 10/3 for the roller bearing.

The relation between life in million revolutions and life in hours is given by:

where, L_10h= rated bearing life in hours and N = speed of rotation in rpm.

Calculation:

Given:

N = 1500 rpm, P = 6 kN, L_10h = 8100 hours, roller bearing k = 10/3

We know that;

and;

Combining both equations:

C = 43.34 kN