Bevel Gears
Types of bevel gears include:
Straight bevel gears.
This is the most common type of bevel gear where the teeth are radial to the point of intersection of the shaft axes or apex. The teeth are similar to spur gears in that they make a line contact across the face of the teeth but they are smaller at the front end than at the rear of the teeth. The shaft angle most commonly encountered is 90º and when of this angle and of equal speeds they are termed mitre gears.
Spiral bevel gears.
This type of gear fulfils the same purpose as straight bevel gears but the teeth have a form of spiral or developed curve in the longitudinal direction. In other words, spiral bevel gears have the same relationship to straight bevel gears as do helical gears to spur gears in that they transmit motion more smoothly than straight bevels.
Zerol bevel gears.
The teeth of Zerol bevel gears are curved but lie in the same direction as the teeth of straight bevels (along the axis), with a mean spiral angle of zero.
Hypoid gears.