Bevel gears are of help when the direction of a shaft’s rotation must be changed. They are often installed on shafts that are 90 degrees aside, but could be designed to work at additional angles as well.
One’s teeth on bevel gears could be straight, spiral or hypoid. Right bevel gear teeth actually have the same issue as straight spur gear tooth — as each tooth engages, it impacts the corresponding tooth all at one time.
Exactly like with spur gears, the perfect solution is to this problem is to curve the gear teeth. These spiral teeth engage just like helical teeth: the contact starts at one end of the gear and progressively spreads across the whole tooth.
On direct and spiral bevel gears, the shafts should be perpendicular to one another, but they must also be in the same plane. In the event that you were to lengthen the two shafts at night gears, they would intersect. The hypoid equipment, however, can engage with the 
axes in different planes.
Hypoid bevel gears in an automobile differential
This feature is used in many car differentials. The band equipment of the Vacuum Pump differential and the input pinion gear are both hypoid. This allows the insight pinion to be mounted less than the axis of the band gear. Figure 7 shows the input pinion engaging the ring gear of the differential. Since the driveshaft of the automobile is connected to the input pinion, this also lowers the driveshaft. This means that the driveshaft doesn’t intrude in to the passenger compartment of the automobile as much, making more room for people and cargo.