Type of Gears

In technology, the word gear is used to designate a machine element having a purpose of transmitting/receiving power and motion from/to a rotating shaft by means of progressive engagement of their edges called teeth.

In mechanical engineering, gears are generally used for power transmission and they are commonly placed in one of the following types:

Those transmitting power and motion between parallel shaft (i.e ordinary helical gears)
Those transmitting power and motion between shaft with intersecting axes (i.e bevel gears)
Those where shafts are neither parallel nor intersecting (hypoid gears)

Depending upon the relation between axes, shape of solid on which the teeth are developed, curvature of both tooth-trace and other special characteristic, different types of gears are shown below.