Question

A straight (cylindrical) roller bearing is subjected to a radial load of 20.2 kN. The life is to be 8000 h at a speed of 940 rev/min and exhibit a reliability of 0.9. What Basic Load Rating should be used in selecting the bearing from a catalog of manufacturer 2 in Table 11-6?

The catalog load rating _____ kN.

Answer 1

Basic load rating, C is the catalog load rating life of 10 ⁶ revolutions.

For the reliability of 0.9, catalog load rating, C ₁₀ ,which causes 10% of a group of bearings to fail at the bearing manufacturer's rating life.

Following formula is applicable.

C ₁₀ = F _R (L _D/ L _R) ^1/a ,

Where a = 10/3 for cylindrical roller bearing

F _R = Radial load = 20.2 KN

L _R = 10 ⁶ rev

L _D = Life in revolutions = (8000 h * 60 min)* 940 rev/min = 451.2 million revolutions.

Put everything in formula,

C ₁₀ = 20.2 ( 451.2) ^3/10

C ₁₀ = 126.375 KN