A-WK26-AI Woodruff Keys, 1/4 x 1-1/8One New Aftermarket Replacement Woodruff Key 1 4 x 1 1 8 (ANSI ASME 809, SAE No. 18) This 1 4 x 1 1 8 inch semi circular Woodruff key is a standard replacement fastener used to secure rotating components such as pulleys, gears, flywheels, and sprockets to a shaft. Seated in a half moon keyway cut into the shaft, the key prevents independent rotation between the shaft and the hub while also acting as a designed fail safe that protects more expensive