Part 2: The Engineering Behind the Circular Loop

The coiled loop at the base of a safety pin is called a torsion spring (or helical spring).

Invented by Walter Hunt in 1849, the safety pin relies on a single continuous piece of rigid wire. The circular loop isn’t designed as a hole to put things through—it is a functional spring mechanism that stores mechanical energy when compressed, allowing the sharp pin arm to snap back open automatically when released from its protective clasp.

👇 HEAD TO PART 3 TO LEARN THE 4 MECHANICAL FUNCTIONS OF THE LOOP!