An Internal Gear could be described as the contrary of an external gear in that one’s teeth point towards instead of away from the center, and addendum and dedendum consider invert positions. Internal Gears provide a compact parallel shaft tranny drive with large acceleration reduction. Used with a standard spur pinion the ratio is the same as that of two external gears, however the center distance is much smaller. In cases where it’s important to have two parallel shafts rotate in the same direction, the internal gear eliminates the use of an idler gear.
Internal Gears possess a number of advantages when properly used. One such benefit is reduced sliding actions. The corresponding working surfaces of one’s teeth of an internal equipment and pinion are more nearly of the same size than may be the case with an exterior gear and pinion getting the same tooth ratio and tooth length. Therefore the relative slippage of one’s teeth is less regarding the internal. This point presents among the advantages of using Internal Gears. The sliding actions of one tooth over another causes friction; and because friction outcomes in tooth put on, a reduction in the amount of sliding action is usually desirable.
Internal Gear drives could be operated with the apparatus in a fixed position and the pinion rotating along the pitch line, or the apparatus may be absolve to rotate with the pinion rotating in a fixed position.
When mating pinions are too close in size to the apparatus, interference may result. As a result, the difference in teeth of the pinion to the gear 
should not be less than 15.
RUSH GEARS inc. provides standard Internal Gears in Metal, STAINLESS STEEL, CAST IRON, BRONZE, Light weight aluminum, DELRIN and nonmetallic (PHENOLIC). We will gladly planetary gearbox manufacture made to order Internal Gears to your requirements.