Missouri Valley 1-4 Practice Test 2026 – Complete Exam Prep

An expansion anchor works by converting the tightening of the bolt into outward pressure against the walls of the drilled hole, causing the anchor to grip the surrounding material. This mechanical expansion is a classic feature of what’s historically called a patent anchor. The name comes from the idea of a patented design that expands to lock into masonry or concrete, providing a secure hold through friction and mechanical interlock rather than just a simple fastener.

Other options don’t fit because they aren’t established names for this expanding mechanism. Bang isn’t a recognized type, and terms like collapsible or feather don’t describe the expansion action that locks into the hole. The traditional term that correctly identifies this expanding mechanism is patent anchor.