Brock Institute for
Advanced Studies all rights reserved
Hookless #2 Slide Fastener
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This animation shows the inner workings of a conventional metal slide fastener (zipper). The scoop and slider dimensions were taken from a Hookless #2, probably of 1920s vintage. Its design is somewhat advanced from the original, its slider pull claiming patents from the original March 20, 1917 to November 25, 1919.
Some people describe the action of the slider as 'forcing' the chain together and apart as it travels up and down the fastener, but an inspection of the way that the scoops move within the slider shows that there's no interference at all. The scoops engage and disengage with a motion closely related to that of gear teeth.