Fatigue Life Comparison of Ball and Tapered Roller Bearings Under Wheel Bearing Load Conditions

Fatigue life performance of close-coupled wheel bearings is of significant interest to vehicle manufacturers. Performance requirements continue to increase as designs become more compact, wheel loads increase and vehicle warranties are extended. The automotive designer is faced with the fundamental decision of selecting between ball or tapered roller bearings. This decision is critical to achieving optimum performance.

To determine the relative performance differences between close- coupled ball bearings and tapered roller bearings, laboratory tests were conducted under two wheel bearing load cycles. Results show that enhancements to the tapered roller bearing internal geometry significantly increase fatigue life performance. Results also show the tapered roller bearing to give over five times the life of the angular contact ball bearing. The superior performance of the tapered roller bearing provides the designer with two options. He can either take advantage of the increased performance to meet the more severe life requirements of the future or he can reduce the bearing package size while still maintaining life equivalent to that of the ball bearing.