A-WK21-AI Woodruff Keys, 7/32 x 1One New Aftermarket Replacement Woodruff Key 7 32" x 1" (SAE) This 7 32" x 1" Woodruff key (half moon key) is a semi circular shaft key used to lock gears, pulleys, sprockets, and hubs to rotating shafts, preventing independent rotation. It seats into a matching keyseat machined into the shaft and interfaces with the keyway in the mating component to transmit torque. Woodruff keys are also designed to act as a fail safe, shearing under overload to