A Woodruff key is a mechanical component that secures gears, hubs, and other parts to prevent independent movement from a rotating shaft or spindle. It functions as a sacrificial element that safeguards expensive components by breaking under excessive forces.

A Woodruff key resembles a half-moon or semicircle shape with a proportional length that typically sits within a rounded cavity on the shaft. This rounded cavity is termed a circular pocket or depression but is generally known as a woodruff keyway.

The rounded bottom section is driven into the shaft while the flat upper portion fits into the hub keyway. This particular key type proves simple to extract but challenging to install.

The extended flat surface of the Woodruff key projects beyond the primary shaft after installation. When a corresponding hub, gear, or other component is forced onto the shaft, the extending portion of the key binds the elements into a single unit.

The key must maintain proper positioning and stability in its primary seating. If the key lacks proper fit or stability, its curved lower profile might cause it to dislodge from the key seat.

The shaft's structural integrity may decrease due to the additional depth required for the key. Because of the key's increased depth requirement, it connects directly with the matching component, eliminating any space between these elements.

Advantages of Woodruff Keys
1. The Woodruff key offers simplicity and adaptability.
2. The precise fit between shaft and key eliminates gaps, reducing stress concentration and enhancing shaft reliability.
3. Well-suited for high-speed operations and works where other keys tend to fail.
4. Simple to remove.
5. Capable of adjusting and aligning with shaft movements.

Disadvantages of Woodruff Keys
1. The groove design makes installation challenging.
2. Not suitable for high loads.
3. Increased depth requirements may compromise shaft strength.