Gear Types- Review

The spur gear is the most common gear type. The teeth on these gears are straight. Spur gears are basically used for transmitting power between two parallel shafts, for example, a bicycle wheel. 

Helical gears have curved teeth, which mesh together better than spur gears. The curved teeth allow them to operate more smoothly and Quietly than spur gears. 

The internal annual gear has teeth inside a ring, which allows shafts with gears on the end to fit in, for example, a salad spinner and a lawn mower. 

The compound gear is made up of several gears of different sizes. Spinning a single shaft moves all of the gears at the same time. 

The worm gear is thin in shape, and is used to achieve high gear ratio, or Mechanical advantage. This gear also enables one to change the axis angle by 90 degrees, for example, in an electric mixer and a lawn sprinkler. 

The crown gear is similar to a spur gear, but its teeth are curved. It fits easily with the worm gear and can be used to change the axis angle by 90 degrees.

Bevel gears, like worm gears, also allow some change to the axis angle, for example, in a manual eggbeater.