An planetary gearbox Internal Gear could be described as the contrary of an external gear in that the teeth point towards instead of away from the center, and addendum and dedendum consider reverse positions. Internal Gears give a small parallel shaft transmission drive with large quickness reduction. Used with a typical spur pinion the ratio is equivalent to that of two external gears, but the center distance is a lot smaller. In cases where it is necessary to possess two parallel shafts rotate in the same direction, the inner gear eliminates the use of an idler gear.
Internal Gears possess several advantages when properly applied. One such benefit is reduced sliding actions. The corresponding working surfaces of one’s teeth of an internal gear and pinion are more almost of the same length than is the case with an exterior gear and pinion getting the same tooth ratio and tooth duration. Therefore the relative slippage of the teeth is less in the case of the internal. This point presents one of the advantages 
of using Internal Gears. The sliding actions of one tooth over another causes friction; and because friction results in tooth use, a reduction in the amount of sliding action is usually desirable.
Internal Gear drives may be operated with the gear in a set position and the pinion rotating along the pitch line, or the gear 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. Consequently, the difference in teeth of the pinion to the gear should not be significantly less than 15.
RUSH GEARS inc. offers standard Internal Gears in STEEL, STAINLESS, CAST IRON, BRONZE, ALUMINUM, DELRIN and nonmetallic (PHENOLIC). We will gladly produce made to order Internal Gears to meet your needs.