Rolling Contact Bearings

Two ball bearings from different manufacturers are being considered for a certain application. Bearing A has a catalog rating of 2.0 kN based on a catalog rating system of 3000 hours at 500 rev/min. Bearing B has a catalog rating of 7.0 kN based on a catalog that rates at \(10^6\) cycles. For a given application, determine which bearing can carry the larger load.

A shaft rotating at constant speed is subjected to variable load. The bearings supporting the shaft are subjected to stationary equivalent radial load of 3 kN for 10 percent of time, 2 kN for 20% of time, 1 kN for 30% of time and no load for remaining time of cycle. If the total life expected for the bearing is \(20\times10^6\) revolution at 95% reliability, calculate dynamic load rating of the ball bearing.

Shown in the figure below is a gear-driven squeeze roll that mates with an idler roll. The roll is designed to exert a normal force of 6.12 N/mm of roll length and a pull of 4.90 N/mm on the material being processed. The roll speed is 350 rev/min and a design life of 35 kh is desired. Use an application factor of 1.2 and select a pair of angular-contact 02-series ball bearings to be mounted at O and A. Use the same size bearings at both locations and a combined reliability of at least 0.92. Dimensions in the figure are in mm.