Question

The following figure shows two bearings supporting a 0.08×10^3-rpm shaft and gear. The bearing on the left carries a 4.07kN radial load and 0.32kN thrust load. The loading is borderline between “light” and “moderate” impact. The required life is 4000 hours with only 2% probability of failure. What is the required bearing capacity in kN? Solve to 2 decimal spaces. An error of 5% is allowed for. T4 Q3.PNG

The following figure shows two bearings supporting a 0.08x10^3-rpm shaft and gear. The bearing on the left carries a 4.07kN radial load and 0.32kN thrust load. The loading is borderline between "light" and "moderate" impact. The required life is 4000 hours with only 2% probability of failure. What is the required bearing capacity in KN? Solve to 2 decimal spaces. An error of 5% is allowed for. Gear Shaft Bearing

Answer 1

Refer first 3 images as standard data for solving the problem. This standard data is taken from textbook.

TABLE 14.3 Application Factors K. Type of Application Ball Bearing Roller Bearing 1.0 1.0 1.0-1.3 1.0 Uniform load, no impact Gearing Light impact Moderate impact Heavy impact Scanned with CamScanner 1.2-1.5 1.5-2.0 2.0-3.0 1.0-1.1 1.1-1.5 1.5-2.0

Life adjustment reliability factor K, 0.2-FIGURE 14.13 0.1-Reliability factor K, 97 98 99 100 90 91 92 93 94 95 96 Reliability (%) Scanned with CamScanner

a = 0° (radial ball bearings) For 0 < F/F, < 0.35, Fe = F, For 0.35 < F,/F, < 10. Fe = F, 1 + 1.115 CS Scbited with Cam Sannefe = 1.176F, Per 0.35 <FF, < 10. - -+1.186. – 035)]} 14.3 0.35 (14.3)2

Given: Radial Load Er = 4.07 KN Thrust Load Ft = 0.32 KN Life, L= 4000 hrs with 2% probability of failure le 98% reliability N:0.08 x 103:80 rpm 1. Fr = 4:07 KN , ft:0.32 KN 2. Et i Fr = 0.3214.07 = 0.0786 3. From Table 14.3, - For light-moderate impact. Ka = 1.5 4. L: 4000 hours = ( 4000 hrs) (80 revimin ) (60 minthy) - L=19. 2x 106 her 5. From figure 14.13. - with 98% reliability Kr=0.33 S Scanned with CamScanner

6. The Life corresponding to rated capacity_LR: 90x100 rer 7 For xadial bearing from equation 14,3 as 0 < Ft/Fr <0.35 Equivalent load. Fe = fr .: Fee 4.07 KN 8. For radial bearing, The required value of rated capacity Creg : Feka ( 2 ja 3 kr LR) - 4.07 x15xl 19.2x10° 1 0.33x90x106 Creq = 5.356 kN CSScanned with CamScanner