Power loss, contact stress, dynamic load capacity and fatigue life of a tapered roller bearing as functions of the number of rolling elements
Abstract
The number of rolling elements of a roller bearing influences its operating results, such as contact stress, dynamic load capacity, fatigue life, friction torque, and power loss. Comparing a standard roller bearing with a modified one, where the modification refers only to the number of rolling elements, a lower number of rolling elements reduces power loss and fatigue life but increases contact stress. This study proposes reducing the number of rolling elements in a tapered roller bearing (TRB) to improve its energy efficiency. To evaluate this proposal, friction torque, power loss, contact stress, dynamic load capacity, and fatigue life were determined through analytical calculations. For the input data, a manual automotive transmission of a passenger vehicle was selected. The standard TRB considered has 23 tapered rollers, and it was evaluated analytically considering 23, 22, 21, 20, 19, and 18 rolling elements. The results indicate that the contact stress exhibits a quadratic variation with the reduction in the number of tapered rolling elements. Additionally, the modified TRB with 18 rolling elements (21.74% reduction) led to a 15.03% reduction in power loss, a fatigue life 10.8 times greater than the required 69,000 km for the considered life cycle, and a contact stress (2.19 GPa) that did not exceed the 4 GPa limit established by the ISO 76 standard.