1.  Spur Gears  Known as the common gear.  Strong  Easy to manufacture  Cost effective  Makes noise under curtain types of load.  Common use: Industrial applications where gear noise is not a concern.

2.  Helical  Strong  Moderate difficulty in manufacturing.  Reduced noise at higher revelation speeds.  Common use: Manual transmission in an automobile.

3.  Herringbone  AKA: Double Helical  Very difficult to manufacture  Expensive  Does not require a thrust bearing. Side load is pushed to the center of the gear and does not allow for gear misalignment.  Very smooth  Common use: Large displacement pumps

4.  Spur Bevel  Same rules as a common spur gear.  Used when an output shaft location requires offset location.  Often 90 degrees of separation from input shaft to output shaft. Other degrees of separation are possible with a change in gear geometry.  Common use: Roll up doors and angle grinders.

5.  Spiral Bevel  Similar to the Spur Bevel gear.  Used when a smother and quieter application is required.  Difficult to manufacture  High strength  Bevel gears of equal size are often known as Miter gears.  Hypoid gears are arranged with the pinion above or below the ring gear centerline. Thus allowing for bigger and stronger pinion gears.  Common use: Differential in an automobile.

6.  Worm  Used when an output shaft location requires offset location and additional gear reduction is required.  Advanced manufacturing  Input and output are not interchangeable.  Considered to be a self locking.  Common use: Conveyer belts, presses and other industrial machinery.

7.  Rack and Pinion  Moderate strength  Less difficult to manufacture.  Used to convert rotational motion to linear motion.  Lesser mechanical advantage  Reduced gear backlash offers great feel if manually controlled by a human.  Common use: Steering mechanism in automobile

8.  Planetary  Very strong  Advanced manufacturing  Light weight  Very low noise  Can be stacked for additional gear reduction.  Can be manipulated to create a reverse direction output.  Common use: Shifting transmissions on power drills and automobiles.