An Internal Gear could be described as the opposite of an external equipment in that the teeth point towards instead of away from the guts, and addendum and dedendum consider reverse positions. Internal Gears give a compact parallel shaft transmitting drive with large velocity 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 is necessary to have two parallel shafts rotate in the same path, the inner gear eliminates the use of an idler gear.
Internal Gears possess a number of advantages when properly applied. One such advantage is reduced sliding action. The corresponding working areas of the teeth of an internal gear and pinion are more almost of the same duration than may be the case with an external gear and pinion getting the same tooth ratio and tooth duration. Therefore the relative slippage of the teeth is less planetary gearbox regarding the internal. This aspect presents one of the benefits of using Internal Gears. The sliding action of 1 tooth over another causes friction; and as friction outcomes 
in tooth put on, a reduction in the amount of sliding action is desirable.
Internal Gear drives could be operated with the gear in a fixed position and the pinion rotating along the pitch line, or the apparatus may be free to rotate with the pinion rotating in a fixed position.
When mating pinions are too close in size to the apparatus, interference may result. For that reason, the difference in teeth of the pinion to the gear should not be significantly less than 15.
RUSH GEARS inc. offers regular Internal Gears in STEEL, STAINLESS, CAST IRON, BRONZE, ALUMINUM, DELRIN and NON-METALLIC (PHENOLIC). We will gladly manufacture made to purchase Internal Gears to meet your needs.