11-1 Timken rates its bearings for 3000 hours at 500 rev/min. Determine the catalog rating for a ball bearing running for 10 000 hours at 1800 rev/min with a load of 2.75 kN with a reliability of 90 percent. 11-2 A certain application requires a ball bearing with the inner ring rotating, with a design life of 25 kh at a speed of 350 rev/min. The radial load is 2.5 kN and an application factor of 1.2 is appropriate. The reliability goal is 0.90. Find the multiple of rating life required, xp, and the catalog rating Co with which to enter a bearing table. Choose a 02-series deep-groove ball bearing from Table 11-2, and estimate the reliability in use. 11-3 An angular-contact, inner ring rotating, 02-series ball bearing is required for an application in which the life requirement is 40 kh at 520 rev/min. The design radial load is 725 lbf. The application factor is 1.4. The reliability goal is 0.90. Find the multiple of rating life xp required and the catalog rating Co with which to enter Table 11-2. Choose a bearing and estimate the existing reliability in service. 11-4 The other bearing on the shaft of Problem 11-3 is to be a 03-series cylindrical roller bearing with inner ring rotating. For a 2235-lbf radial load, find the catalog rating C1o with which to enter Table 11-3. The reliability goal is 0.90. Choose a bearing and estimate its reliability in use. 11-5 Problems 11–3 and 11-4 raise the question of the reliability of the bearing Page 614 pair on the shaft. Since the combined reliabilities Ris RR2, what is the reliability of the two bearings (probability that either or both will not fail) as a result of your decisions in Problems 11-3 and 11-4? What does this mean in setting reliability goals for each of the bearings of the pair on the shaft? 11-6 Combine Problems 11-3 and 11-1 for an overall reliability of R=0.90. Reconsider your selections, and meet this overall reliability goal.