Comparison of Tooth Bending Strength of Speed-increasing and Speed-reducing Involute Spur Gears

Speed-increasing gears are key parts of many gear transmission systems, for instance, wind turbine gearboxes. Due to the friction force between contacting gear tooth surfaces, the meshing characteristics between speed-increasing and-reducing gear pairs are different, therefore, the knowledge and experience of the former cannot be directly applied to the latter. Based on the most widely used involute spur gears, employing the bending strength calculation standards and Abaqus software, the tooth bending stress under speed-increasing and-reducing cases are analyzed and compared. The comparison shows that, with the same transmission power, the maximum speed-increasing bending stress of the gear will decrease for the dedendum area, and increase for the addendum area by 27.8%, compared with the speed-reducing case. On the contrary, the bending stress of pinion will increase for the dedendum and decrease for the addendum. This work will help to develop a new approach for the design and modification of speed-increasing gears.