Bevel gears are of help when the path of a shaft’s rotation must be changed. They are usually installed on shafts that are 90 degrees aside, but can be designed to work at other angles as well.
One’s teeth on bevel gears can be direct, spiral or hypoid. Right bevel gear teeth actually have the same issue as Screw Vacuum Pump straight spur equipment teeth — as each tooth engages, it impacts the corresponding tooth all at one time.
Just like with spur gears, the solution to this problem is to curve the apparatus teeth. These spiral teeth engage exactly like helical tooth: the contact starts at one end of the apparatus and progressively spreads over the whole tooth.
On straight and 
spiral bevel gears, the shafts should be perpendicular to each other, but they must maintain the same plane. If you were to prolong the two shafts past the gears, they would intersect. The hypoid gear, on the other hand, can build relationships the axes in different planes.
Hypoid bevel gears in an automobile differential
This feature is utilized in many car differentials. The band equipment of the differential and the input pinion equipment are both hypoid. This allows the insight pinion to be mounted less than the axis of the band gear. Figure 7 displays the input pinion engaging the band equipment of the differential. Because the driveshaft of the automobile is connected to the input pinion, this also lowers the driveshaft. This means that the driveshaft doesn’t intrude into the passenger compartment of the car as much, making even more room for people and cargo.
