This precision-machined piece of steel sits half in a slot on a shaft and half in a matching slot in a hub, gear, or pulley. It forces the two components to rotate together while usually allowing them to slide axially during assembly. They come in various profiles, including square, Woodruff, and tapered, and are often designed to shear off before catastrophic overload damages the expensive shaft.
Heard on the job
Make sure you tap the key all the way into the slot before you try to press that drive sprocket onto the motor shaft.
Also heard as
- Woodruff key
- parallel key