*2.3.4 Life of bearing in revolutions*

The life of an individual ball bearing may be defined as the number of revolutions which the bearing runs before the first evidence of fatigue develops in the material of one of the rings or any of the rolling elements.

The rating life of a group of apparently identical ball bearing as the number of revolutions that 90% of a group of bearings will complete or exceed before the first evidence of fatigue develops:

$$\mathbf{L\_n} = \left(\frac{\mathbf{C\_d}}{\mathbf{P}}\right) = \frac{\mathbf{14.8}}{2} = \mathbf{12.3} \tag{13}$$

P = weight of pulley + weight of shaft. P = total load (.400 + .800) = 1.2 kg. Life of bearing = 1800 million revolution.

*2.3.5 Bearing number*

*2.3.2 The maximum load per ball*

C = capacity of the bearing.

where HP in kW, N in rpm.

*2.3.3 Basic dynamic load of bearing*

n = no. of balls.

*Axial view of ball bearing.*

*Foams - Emerging Technologies*

**Figure 7.**

T = 5.19 N m.

Cd ¼ 14807*:*3 N*:* Cd ¼ 14*:*8 kN*:*

**94**

Fc <sup>¼</sup> <sup>4</sup>*:*<sup>37</sup> n

*<sup>C</sup>* <sup>¼</sup> <sup>7200</sup> � <sup>8</sup> � *:*007<sup>2</sup>

C ¼ 6*:*45 kg*:*

Fc <sup>¼</sup> <sup>4</sup>*:*<sup>37</sup> 8

Cd <sup>¼</sup> Fc � ð Þ n cos *<sup>α</sup> <sup>o</sup>:*<sup>7</sup>

Torque <sup>¼</sup> <sup>9550</sup> � <sup>H</sup>*:*<sup>P</sup>

<sup>4</sup>*:*<sup>37</sup> <sup>¼</sup> Knd2

<sup>4</sup>*:*<sup>37</sup> *:*

� 6*:*45

<sup>N</sup> <sup>¼</sup> <sup>9550</sup> � *:*<sup>75</sup>

Z2*=*

<sup>¼</sup> <sup>3</sup>*:*<sup>46</sup> � ð Þ 8 cos 15 <sup>0</sup>*:*<sup>7</sup> � <sup>47</sup><sup>1</sup>*:*<sup>8</sup>*:*

<sup>1380</sup> *:*

<sup>C</sup> <sup>¼</sup> Fc � <sup>n</sup>

� C (10)

<sup>4</sup>*:*<sup>37</sup> (11)

3D<sup>1</sup>*:*<sup>8</sup> (12)

```
Bore diameter = 20 mm.
Outer race diameter = 47 mm.
ISI no. = 20BC02.
Bearing of basic design no. = 04.
Basic capacity of dynamic load = 1000 kg.
```