Which item holds components in place such as gears on a shaft normally entirely threaded and internally wrenched?

Which item holds components in place such as gears on a shaft normally entirely threaded and internally wrenched?

• A. barrel
• B. bolt
• C. set screw
• D. quick release panel fastener

Answer: (C)

The function described matches a set screw. This fastener is designed to hold components like gears, pulleys, or collars in place on a shaft by applying a clamping force. It is normally fully threaded along its length and tightened with an internal drive, such as an Allen (hex) wrench, so there’s no big head sticking out. When you tighten it, the screw threads into a threaded hole or against a deformed surface inside the hub, pressing against the shaft and locking the parts together. That combination—complete threading and an internal wrench—makes it ideal for securing rotating parts on a shaft. The other items don’t fit the scenario: a barrel is not used to clamp gears on a shaft, a bolt typically has a head and is used with a nut or threaded hole—not usually entirely threaded for this clamping purpose, and not tightened by an internal drive in the same way, and a quick release panel fastener is meant for easy panel removal rather than securing rotating components on a shaft.

The function described matches a set screw. This fastener is designed to hold components like gears, pulleys, or collars in place on a shaft by applying a clamping force. It is normally fully threaded along its length and tightened with an internal drive, such as an Allen (hex) wrench, so there’s no big head sticking out. When you tighten it, the screw threads into a threaded hole or against a deformed surface inside the hub, pressing against the shaft and locking the parts together. That combination—complete threading and an internal wrench—makes it ideal for securing rotating parts on a shaft.

The other items don’t fit the scenario: a barrel is not used to clamp gears on a shaft, a bolt typically has a head and is used with a nut or threaded hole—not usually entirely threaded for this clamping purpose, and not tightened by an internal drive in the same way, and a quick release panel fastener is meant for easy panel removal rather than securing rotating components on a shaft.