1. The Zipper
By: Chris Henry

2. What is a Wedge?
A wedge is a simple machine made up of two inclined planes put together. These 2 planes meet and form a sharp edge.
Wedges are used to push two objects apart, or cut an object into pieces. It can also hold objects in place.
Examples: Doorstop, knife, zipper, fork, axe, icepick, needle, scissors, etc.

3. Origin of The Zipper
The Zipper was an Invention that almost 60 years to be completed. Multiple people are responsible for its creation (Elias Howe, Whitcomb Judson and Gideon Sundback).
It all started in 1851 when Elias Howe received a patent for the “Automatic Continuous clothing closure.” But he didn’t market it because he was promoting the sewing machine.

4. Continued…
40 years later a man named Whitcomb Judson improved Howe’s idea and he began to market it as the “Clasp locker.” He started the Universal Fastener Company in 1893 to market his product but it didn’t have much success.
Eventually in 1913 Gideon Sundback invented what we know as the modern Zipper. But Gideon invention was actually called the “Separable Fastener.” The B.F Goodrich Company used Sundback’s fastener on a new type of boot and they called it the Zipper. Eventually the name stuck.

5. How does it Work?
A zipper has two rows of teeth on each side facing one another. Each one of the teeth has a hook and they are opposite from one another so as they are pulled towards one another they connect in sequence. A zipper is closed when the hooks enter the hollow space but the teeth have to be the same size and shape as the hollow otherwise the zipper won’t close.
The slide part of the zipper contains wedges that push the hooks and hollows together at specific angles to close it. In order to unzip the closure the pull is pushed against the hooks in the opposite direction and detaches the teeth. The stops at each end of the zipper are what prevent the slider from coming off of the teeth.

6. Diagram

7. References