Helical Bevel Gear

Bevel gears are gears where the axes of the two shafts  intersect and the tooth-bearing faces of the gears themselves are conically shaped. Bevel gears are most often mounted on shafts that are 90 degrees apart, but can be designed to work at other angles as well.

The axles usually meet at an angle of 90 degrees, although they can work at other angles. With the potential to change the direction of force and the operating angle of machinery, a bevel gear has many different applications. Bevel gears use different numbers of teeth to increase speed.
 
Advantages :
1. Compared to straight bevel gears, they possess higher strength.
2.Ability to grind gear tooth surfaces leads to production of higher precision gears.