What does a gear do?

Answer 1

a gear is used to transport force.

Answer 2

Gears transmit motion from one shaft to another. They may be round, but they do not have to be round. Round gears may have any integer number of teeth, and they will mesh with any other round gear with the same thickness and pitch. Noncircular gears which form a complete shape, such as an ellipse, may also be used to transmit mtion -- but the result will be a variable motion. Elliptcal gears must be matched with specific other elliptical gears, and are generally made in matched sets. They are used in printing presses and in packaging machinery, as well as in other applications. Other noncircular gears, such as spiral gears, are not used for giving continuous rotary motion but rather for giving an angular function. Such gears are found in, for example, jet aircraft instrumentation.