The right pair of bevel gears let the transmission have more efficiency.
The bevel gears are important components in transmission systems for changing the direction of drive from horizontal to vertical or other changing mode. The drive bevel gear and driven bevel gear should be exactly positioned, so that when the teeth of the bevel gears meshing, the impacting noise could be slight and the abrasion could be uniform.
Generally, there are two types of bevel gear, straight bevel gears and spiral bevel gears.
Straight bevel gears
In Straight bevel gears, the teeth are straight and parallel to the generators of the pitch cone. Compared with spiral miter gears, straight bevel gears can be made in smaller sizes.
Spiral bevel gears
Spiral bevel gears have their teeth formed along spiral lines. They are somewhat similar to cylindrical helical gears in that the teeth are angled; however, with spiral gears the teeth are also curved. Spiral bevel gears have a strength, oscillation, and noise level advantage over straight bevel gears.