Hypoid gears are cone shaped gears similar to spiral bevel gears except they transmit motion between non-intersecting shafts. The small gear shaft (hypoid pinion side) is offset from the larger gear shaft (hypoid gear side). Given the proper offset amount, the pinion shaft and large gear shaft can pass each other without interference, enabling the shafts to be supported securely on both ends.
Generally, compared with bevel gears, hypoid gears can obtain higher speed reduction. Their large contact ratio allows heavier load transmission compared to similar size bevel gears. Also because of the smooth meshing, it is possible to further suppress noise and vibration. However, the meshing is very complicated and the production itself is more difficult.
As mentioned before, it is possible to obtain very high speed reduction with one pair of hypoid gears. Compared to worm gear drives of similar high speed reduction, hypoid gears generally have the following advantages.
- Both pinion and gear can be heat treated resulting in high rigidity which leads to a smaller unit.
- Less sliding and high efficiency result in smaller capacity motors.
- Compared to worm, the offset between pinion and gear is small with resultant space savings.
