What type of gear feature helps in reducing stress concentrations?

The feature that helps in reducing stress concentrations in gears is the fillet radius. The fillet radius is the rounded transition where the tooth meets the gear body, which prevents sharp corners that can create points of high stress concentration. These sharp corners are prone to crack initiation under load, leading to premature failure. By incorporating a fillet radius, the stress is distributed more evenly across the gear tooth, enhancing its strength and durability.

In contrast, the involute profile primarily relates to the shape of the gear teeth and how they mesh with each other, which optimizes the transmission of motion but does not specifically address stress concentration issues. Tooth hardening increases the surface hardness, providing resistance to wear but does not directly influence the distribution of stress around critical areas. Helical design offers advantages in smooth running and load distribution due to the angle of the teeth but is not focused on mitigating stress concentrations at critical points in the gear structure.