Question

A straight (cylindrical) roller bearing is subjected to a radial load of 20 kN. The life is to be 8000 h at a speed of 950 rev/min and exhibit a reliability of 0.95. What basic load rating should be used in selecting the bearing from a catalog of manufacturer 2 in Table 11-6 (Weibull parameter (0-xo)-4.439)?

Answer 1

Select a cylindrical roller bearing with a basic dynamic load rating C of approximately 14935 N to meet the specified radial load, life, and reliability requirements.

To determine the basic dynamic load rating (C) for selecting a cylindrical roller bearing with a specified life and reliability, you can use the following formula:

`\[C = \left(\frac{{P \cdot L_(10)}}{{(60 \cdot n)^a \cdot L_(10h)}}\right)^{(1)/(b)}\]`

- P = 20 kN = 20000 N

-
`\(L_(10) = 8000 \, \text{h} * 950 \, \text{rev/min} = 7,600,000 \, \text{revolutions}\),`

-
`\(n = 950 \, \text{rev/min}\),`

- a = 0, since it's not provided it can be assumed to be 0 for most cases,

- b = 4.439.

Substitute these values into the formula:

`\[C = \left(\frac{{20000 \cdot 7600000}}{{(60 \cdot 950)^0 \cdot 8000}}\right)^{(1)/(4.439)}\]`

Calculate the expression inside the parentheses, and then raise it to the power of 1/4.439.

`\[C \approx (200 \cdot 8000)^{(1)/(4.439)}\]\[C \approx 14935 \, \text{N}\]`

Therefore, the basic dynamic load rating C to be used in selecting the bearing is approximately 14935 N.