Lesson 2/Learning Event 2
FIGURE 16. SPIRAL AND HYPOID GEARS.
It was found that, by lowering the pinion below the centerline of the bevel ring gear, the
teeth in mesh could be longer. This meant that the gear set would be still stronger than
the spiral bevel set. It also lowered the propeller shaft and allowed the vehicle body to be
lowered. The improved version of the spiral bevel gear set is known as hypoid gearing.
It is used in many commercial and military vehicles. The pinion and ring gear are both
mounted on the same type bearings as the spiral bevel gearing. The pinion may be above
or below the ring gear centerline. Compare the illustrations of the spiral bevel gears and
the hypoid gears.