Coppiglia

A pin is a small rod that locates two parts, holds them together, or acts as a pivot.

It aligns mating parts, transmits load across a joint, or lets a part rotate about it; types include dowel, split (cotter), and clevis pins.

Pins are used in linkages, hinges, and many assemblies throughout the vehicle. The correct pin matches the hole size and the type the joint needs.