The gear whose indexing surface is a conical surface is called a bevel gear.
According to the shape of tooth line: straight bevel gear, helical bevel gear, curve bevel gear.
Bevel gears are used for cross shaft transmission and crosstransmission.
Correct Meshing Conditions of spur bevel gears
(1) The modulus of large end face of two gears is equal
(2) The tooth angles of the two gears are equal.