An Internal Gear could be described as the contrary of an external gear in that the teeth point towards instead of away from the guts, and addendum and dedendum take reverse positions. Internal Gears give a compact parallel shaft tranny drive with large acceleration reduction. Used with a typical spur pinion the ratio is equivalent to that of two exterior gears, but the center distance is a lot smaller. Where it’s important to possess two parallel shafts rotate in the same path, the internal 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 the teeth of an internal gear and pinion are more nearly of the same length than is the case with an external gear and pinion getting the same tooth ratio and tooth length. Which means relative slippage of one’s teeth is less 
regarding the internal. This point presents one of the advantages of using Internal Gears. The sliding planetary gearbox action of 1 tooth over another causes friction; and since 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 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 the teeth of the pinion to the apparatus should not be less than 15.
RUSH GEARS inc. provides standard Internal Gears in Metal, STAINLESS STEEL, CAST IRON, BRONZE, Aluminium, DELRIN and NON-METALLIC (PHENOLIC). We will gladly manufacture made to order Internal Gears to meet your needs.