An incredibly useful innovation, gears are manufactured and subsequently utilized in a range of industries, ultimately serving to ameliorate and streamline everyday tasks. The advent of gear manufacturing is pinnacle to understanding human modernization and technology throughout the course of our history. When considering the every-day utility of gears in the modern-day, we begin to realize their salience within human antiquity.

 

 

Aristotle’s Writings, The Persian-Developed Water-Lifting Device and Archimede’s Antiythera Mechanism

 

One of the first recorded accounts of the existence of gears is found in 4^th century BC, where Aristotle noted their utility as he described one gear’s ability to drive the direction of the other. Before Aristotle’s writings, the Persians of the 3^rd century developed water-lifting mechanisms that were driven by livestock to retrieve large quantities of water out of open wells. In this configuration, the animal drives a horizontal wheel that meshes with a vertical wheel to lift containers of water out of the well. The container would also be fixed to a smaller gear-driven mechanism. Subsequently, this method would be similarly co-opted for its utility at water-driven mills and other similar configurations.

 

It was also in the 3^rd century that the mathematician Archimedes would invent a device known as the Antiythera mechanism that utilized numerous gears to replicate the positions of astronomical bodies in the sky.

 

 

Da Vinci’s Sketchbooks and Wooden Gears

 

The sketchbooks of Leonardo da Vinci would depict portrayals of various geared mechanisms composed of wood. During the 1400s, wood was the go-to material for gear manufacturing. It wasn’t until much later that the popularity of wood would be replaced by the (eventually) more affordable cast iron alternative.

 

 

The Law of Conjugate Action

 

It was also in the 1400s that scientists and engineers would critically assess their approach in gear manufacturing. Utilizing the era’s more informed understanding of the practical applications of mathematics and science, investigation into gear design with the purpose of streamlining its utility and processes was first conducted by France’s Philip de la Hire. Later, de la Hire’s hypothesis would be confirmed by Swiss mathematician Leonard Euler – who would later gain notoriety for his work behind the Law of Conjugate Action, now commonly known as ‘the law of gearing’. The law of conjugate action dictates that mating gear profiles do not lose contact or intervene with each other while in rotation at constant angular velocity over time.

 

 

England’s Industrial Revolution and the Beginnings of Contemporary Gear Manufacturing

 

The 18^th century would spark the invention of specific gears made for definitive utilities i.e. the cycloidal gears for clocks, water mills, and power machines. Later gear uses and developments would occur as the invention of the locomotive, vehicles, and other types of machinery would materialize.

 

The industrial revolution stimulated the onset of invention – and the need for gears, gear hobbing and shaping technologies began to develop toward the 19^th century, providing the earliest foundations of contemporary commercial gear fabrication and manufacturing. Paving the way for modern interpretations based on need for this human-age old technology, the modern gear has come a long way from its first appearances nearly 2500 years ago.