Spur gear is a classification of gears. According to the relative position and tooth direction of a pair of gear axes (whether the two weeks are parallel or not), it is divided into plane gear rotation and space gear rotation; According to different working conditions of gears, they can be divided into open transmission and closed transmission; According to the shape of gear teeth or tooth profiles, they are divided into straight teeth, oblique teeth, herringbone teeth, or straight teeth and curved teeth.
Gears are divided into spur gears, helical gears, herringbone gears and curved gears according to the shape of tooth lines. Spur gears refer to gears whose teeth are parallel to the axis.