What component on a shaft fits into a keyway to transmit torque?

What component on a shaft fits into a keyway to transmit torque?

• A. Nut
• B. Washer
• C. Key
• D. Pin

Answer: (C)

Torque is transmitted between a shaft and a connected part by locking them together rotationally, which is done with a key and its matching slot. The key fits into slots cut into both the shaft and the hub (the keyway), so when the shaft twists, the hub is carried with it without slipping. The component that fits into that keyway to pass the twisting force is the key. Nuts and washers have other roles like axial fastening and load distribution, while a pin is typically used for locating or, in some designs, protection against overload rather than standard torque transmission through a keyway.

Torque is transmitted between a shaft and a connected part by locking them together rotationally, which is done with a key and its matching slot. The key fits into slots cut into both the shaft and the hub (the keyway), so when the shaft twists, the hub is carried with it without slipping. The component that fits into that keyway to pass the twisting force is the key. Nuts and washers have other roles like axial fastening and load distribution, while a pin is typically used for locating or, in some designs, protection against overload rather than standard torque transmission through a keyway.