A(n) _______ pin is larger in diameter than the hole in which it is installed and compresses to fit the smaller hole.

• A. Dowel Pin
• B. Expansion Pin
• C. Spring Pin
• D. Taper Pin

Answer: (B)

A spring pin is designed to secure parts through interference fit by deforming slightly as it is installed. It is manufactured with a diameter larger than the hole it’s intended for, and when driven into the bore the sides compress and then grip the walls of the hole. This gives a strong, vibration-resistant hold without needing additional fasteners, and the pin can be removed by driving it back out. Dowel pins are used for precise alignment and aren’t meant to deform to fit; expansion pins rely on outward expansion to lock into place, not compression to fit a smaller hole; taper pins require a matching tapered hole and are driven tight rather than compressed to fit. The described behavior—being larger than the hole and compressing to fit—fits the spring pin best.