Spiral bevel gears are bevel gears
with helical teeth set in a 90° angle. The gears have a tooth trace that is curved and the tooth contact area is huge. Spiral bevel gears have a large axial force but produce higher strength and less noise. They have no offsets which means that they do not slip during operation. The result is a smooth and reliable transmission for high torque, high-speed applications. A spiral bevel gear set ought to be changed in pairs like the right hand and left hand gears should be changed at the same time as they manufactured and lapped in pairs. The pinion and spiral bevel gear are usually of opposite hand, including the case which has an internal gear. A right-hand gear is one with the outer half of the tooth inclined in the clockwise direction from the middle of the tooth point while the left-hand gear is inclined in the counterclockwise direction. Spiral bevel gearboxes are suitable for a variety of high-volume applications like the vehicle differential where the drive must be turned in a 90-degree angle from the driveshaft to drive the wheels.