Spur Gear

→ Two shafts exist in parallel, but one gear interlocks inside another gear. 
    As there are many interlocking teeth, vibration is low but large reduction ratio cannot be obtained. This gear can be installed in a small space if used for planet gear.

 Helical Gear

→ To prevent simultaneous interlocking of tooth stems creating during use of spur gear, this gear has tooth stems with twisted curve shape. Helical gear shows low vibration and noise as interlocking of teeth is softer than spur gear. Also, long contact wire allows for transfer of large force and strength. It is more complicated to manufacture than spur gear, and thrust is formed in the direction of shaft. This thrust can be resolved using thrust bearing. (Thrust bearing: withstands shaft load)

 Double Helical Gear

→ Double helical gear removed thrust in the direction of shaft that occurs in general helical gear. The use is similar to general helical gear. It is used for large sized and large capacity gears such as turbine on ships and large capacity reducers.

 Straight Bevel Gear

→ This gear transfers force between two crossing shafts. Bevel gear interlocks in the direction from tooth peak to tooth root, and it has lower contact rate compared to spiral bevel gear.

 Spiral Bevel Gear

→ This bevel gear has tooth stems cut into shape of a spiral. 
    As length of interlocked part is long, it shows soft motion. Especially at high speed, it can reduce vibration and noise. 
    Therefore, this gear is more frequently used than straight bevel gear.

 Worm Gear

→ This gear is used to transfer motion when two shafts are perpendicular instead of being on the same plane. It is characterized by high reduction ratio, small installation space and low gear efficiency. Also, it does not reverse worm in worm wheel, and this trait is used to prevent reversal of winch. This gear is mainly used for reducers and craft machines.