Internal gears have cylindrical pith surface with teeth parallel to the axis and teeth cut from inside the rim rather than outside. These gears are used along with the pinion. Teeth of internal gears carry the load and are evenly distributed. The center distance of given velocity is short. One thing, which should be kept in mind, is that the difference between teeth of girth gear and pinion gear should not be less than 15. Internal gears are used to transmit rotary motion between parallel shafts that rotate in same direction. Internal gearâ€™s non-binding tooth design ensures smooth and quiet operation. Brass, carbon steel, nylon are the metal used in manufacturing the internal gear. These gears provide low sliding and high stress loading. They are used in planetary gears to produce large reduction ratios.
The main applications of internal gears are in rollers, indexing, timing and other light duty applications. They are used as tools for creating solid models of drive components.