US Patent 12094500 Hard disk drive carriage arm depression

A hard disk drive carriage arm includes a top depressed portion or indentation extending from a top surface toward a bottom surface and a bottom depressed portion or indentation extending from the bottom surface toward the top surface and opposing the top depressed portion. As such, a separating structure between the depressed portions partitions a corresponding balance hole, preferably at or near a mid-plane between the top and bottom surfaces. This configuration does not notably increase windage-based power loss while suppressing fluid force fluctuation, thereby stabilizing and balancing the airflow inside of the depressed portions.