|Gears: An Historical Note|
Gears have existed since the invention of rotating machinery. Because of their force-multiplying properties, early engineers used them for hoisting heavy loads such as building materials. The mechanical advantage of gears was also used for ship anchor hoists and catapult pre-tensioning.
Early gears were made from wood with cylindrical pegs for cogs and were often lubricated with animal fat grease. Gears were also used in wind and water wheel machinery for decreasing or increasing the provided rotational speed for application to pumps and other powered machines. An early gear arrangement used to power textile machinery is illustrated in the following figure. The rotational speed of a water or horse drawn wheel was typically too slow to use, so a set of wooden gears needed to be used to increase the speed to a usable level.
An 18th Century Application of Gears for Powering Textile Machinery
The industrial revolution in Britain in the eighteenth century saw an explosion in the use of metal gearing. A science of gear design and manufacture rapidly developed through the nineteenth century.
Today, the most significant new gear developments are in the area of materials. Modern metallurgy has greatly increased the useful life of industrial and automotive gears, and consumer electronics has driven plastic gearing to new levels of lubricant-free reliability and quiet operation.