Keterangan :

Helical gears are very similar to spur gears except the teeth are not perpendicular to the face. The teeth are at an angle to the face giving helical gears more tooth contact in the same area.

Helical gears can also be used on non-parallel shafts to transmit motion.
Helical gears tend to run quieter and smoother than spur gears due to the increased number of teeth in constant contact at any one period of time.