Gears Types

1. According to position of tooth and gear surface, gears can be divided into external gears and internal gears.

2. According to shapes of gears, gears can be divided into spur gears, bevel gears, non-circular gears, racks.

3. According to shapes of gears tooth, gears can be divided into spur gears, helical gears(spiral gears), herringbone gears(double helical gears).

4. According to gear tooth profile, gears can be divided into involute gears, cycloidal gears.

7 Common Gears

1. Spiral bevel gears and Straight bevel gears
spiral bevel gear

2. Hypoid gears

Hypoid gears resemble spiral bevel gears except the shaft axes do not intersect.
hypoid gear

3. Worm gears

Worm gears resemble screws. A worm gear is usually meshed with a spur gear or a helical gear, which is called worm wheel.
Worm gears

4. Epicyclic gears (Planetary gears)
epicyclic drive

5. Harmonic gears
harmonic drive

6. Involute gears
involute gear

7. Cycloid gears (Cycloidal gears)
Cycloidal gears