Zipper
In 1892, Whitcomb L. Judson, an American inventor from Chicago, patented the original design from which the modern device evolved.
If the lower slider is raised then the bottom part of the jacket may be opened to allow more comfortable sitting or bicycling.
Forty-two years later, in 1893, Whitcomb L. Judson, who invented a pneumatic street railway, patented a "Shoe-Fastening".
With the support of businessman Colonel Lewis Walker, Judson launched the Universal Fastener Company to manufacture the new device.
Judson's "clasp locker" had its public debut at the 1893 Chicago World's Fair and met with little commercial success.
Good technical skills and marriage to the plant manager's daughter, Elvira Aronson, led Sundbäck to the position of head designer.
The company moved to Meadville, Pennsylvania, where it operated for most of the 20th century under the name Talon, Inc. Sundbäck worked on improving the fastener, and, in 1909, he registered a patent in Germany.
Sundbäck's work with this firm has led to the common misperception that he was Canadian and that the zipper originated in that country.
[7] In 1916, newspapers in Australia reported displays of the "new hookless fastener", a device from America that "the world has been waiting for" by a live model in the store window of Raynor's of Melbourne.
Gideon Sundbäck increased the number of fastening elements from four per inch (about one every 6.4 mm) to ten or eleven (around every 2.5 mm), introduced two facing rows of teeth that pulled into a single piece by the slider and increased the opening for the teeth guided by the slider.
Within the first year of operation, Sundbäck's machinery was producing a few hundred feet (around 100 meters) of fastener per day.
[citation needed] In March of the same year, Mathieu Burri, a Swiss inventor, improved the design by adding a lock-in system attached to the last teeth, but his version never got into production due to conflicting patents.
The popular North American term zipper (UK zip, or occasionally zip-fastener) came from the B. F. Goodrich Company in 1923.
The company used Gideon Sundbäck's fastener on a new type of rubber boots (or galoshes) and referred to it as the zipper, and the name stuck.
They can also be derailed, causing damage to the sealing surfaces, if the teeth are misaligned while straining to pull the zipper shut.
Pulling on the handle from any direction lifts the pivoting arm's pins out of the zipper teeth so that the slider can move.
A further feature of the invention resides in the shape and configuration of the locking members ... [they are] provided with exterior and interior rounded surfaces, and are somewhat elongated transversely.
Thereby, a snug fit is obtained and at the same time ample provision is given for movement of one on the other without coming out when the fastener is flexed transversely.
At the same time this construction gives facility for relative longitudinal movement, without disengagement.The zipper is analogous in function to a drawstring, but different in mechanism.
In Sundback's invention the teeth are symmetric with "exterior and interior rounded surfaces" that are "elongated transversely".
The maximum force when the slider operates is in between the unlocked and locked positions, giving two stable mechanical equilibria.
Most often, the zipper fails to close due to a worn or bent slider not being able to apply the necessary force to the sides of the teeth to cause them to interlock.
This problem can sometimes be redressed by using small pliers to carefully squeeze the back part of the slider together a fraction of a millimeter.
