Bevel
gears

Straight tooth bevel gears transmit continuous rotary motion between concurrent shafts. In bevel gears, the section of teeth is not constant, but their size gradually decreases towards the smallest part of the wheel. Unlike the case with cylindrical wheels, it is not possible to mesh a conical spool with any bevel wheel of the same module.

Bevel gears should be considered in pairs; both components need to be changed in order to change transmission ratio.

An improvement in cutting these gears is the “Coniflex” method, which creates longitudinal convexity. The latter makes the bevel gears less liable to misalignment.

We also have curved tooth bevel gears, a.k.a. helical or spiral bevel gears. The spiral tooth form translates into greater tooth contact and higher speed capacity. Because meshing of the gear teeth is gradual, spiral bevel gears lend themselves to better adjustment than straight bevel gears, where tooth contact occurs all at once across the face of the tooth; the load is permanently spread out onto two or more teeth, which makes operation overall quieter. Same-size pairs can have greater transmission rate than straight bevel gears.