Gears are machine elements used for the transmission of rotary motion between two shafts. They can also be used to alter the speed and direction of motion. It is also usual that the transmitted motion be uniform, i.e. a constant motion of the driving gear produces constant motion of the driven gear It is this property which eventually determines much of the mathematics of the gear's profile.

Types of Gears edit

HELICAL GEARS: it is the gear in which the teeth are inclined to the axis of rotation. the angle of inclination is called helix angle. the tooth surface generated in helical gear is called involute helicoid. this surface is generated when every point on the angular edge of the paper is cut in the shape of parallelogram wrapped around a base cylinder and unwound generate an involute curve.