**1 Answer**

written 5.3 years ago by |

The basic procedure for the selection of SKF bearing from the manufacturerâ€™s catalogue used in **PSG design data book** consists of the following steps:

(1) Write/Calculate the radial and axial forces acting on the bearing and determine/write the diameter of the shaft where the bearing is to be fitted.

(2) Select the type of bearing for the given application.

(3) Determine the values of X and Y, the radial and thrust factors, from the data book. The values of X and Y factors for all bearings are given in **PSG 4.4**. For DGBB the values of X and Y depend upon two ratios, (Fa/Fr) and (Fa/Co). For all other bearings, the values of X and Y depend upon (Fa/Fr) only.

**The selection of the bearing is, therefore, done by trial and error.**

(4) The static and dynamic load capacities single-row deep groove ball bearings of different series are given on **PSG 4.12 to 4.15**. To begin with, a bearing of light series, such as60, is selected for the given diameter of the shaft and the value of Co is selected from **PSG 4.12 to 4.15** Knowing the ratio, the values of X and Y factors are found from **PSG 4.4**.

(5) Calculate the equivalent dynamic load from the equation. $P = (XVF_r + YF_a)S$

V = race rotation factor (1 for inner race rotating and 1.2 for outer race rotating)

S = service factor (**PSG 4.2**)

(6) Make a decision about the expected bearing life using $L(m r)=\frac{L_{h} \times 60 \times N}{10^{6}}$

(7) Express the life L as $\mathrm{L}_{10}^{\prime}$ in million revolutions with 90% probability of survival.

(8) Determine required capacity $(\mathrm{C})$ of bearing Using $\mathrm{C}=\left(\mathrm{L}_{10}^{\prime} / \mathrm{L}_{10}\right)^{1 / \mathrm{k}} . \mathrm{P},$ where $\mathrm{L}_{10}=1 \mathrm{mr},$ Hence, $\mathrm{C}=\mathrm{P}\left(\mathrm{L}_{10}^{\prime}\right)^{1 / \mathrm{k}}(k = 3$ for ball bearing and $\mathrm{k}=10 / 3$ for roller bearing) - **PSG 4.2**.

(9) Correct (i.e. increase) the capacity using temperature correction factor from **PSG 4.2** if required.

(10) Check whether the selected bearing of the selected series has the required corrected dynamic capacity. If not, select the bearing of the next series and go back to Step (2) and continue. Ball bearings are thus selected by the trial and error procedure. The above procedure is also applicable to other types of bearings.