Woodruff keys fit into a curved keyway on a shaft, transmitting torque to a mating hub or pulley.

Diameter: 3/16"
Length: 1"
Material: Steel
Finish: Zinc
Shape: Woodruff
Nominal Size: #13
Type: Woodruff Key
A woodruff key or half-moon key, is a semicircular shaped, removable key that fits into a matching keyway cut into a shaft, leaving a protruding tab. The tab mates with a matching slot on a device mounted flush upon the shaft e.g. a pulley, thus preventing the device from freely rotating about the shaft. It is widely used in machine tools and in the automotive industry.