An Internal Gear may be described as the opposite of an external gear in that the teeth point towards rather than away from the guts, and addendum and dedendum consider reverse positions. Internal Gears provide a compact parallel shaft transmitting drive with large acceleration reduction. Used with a standard spur pinion the ratio is the same as that of two external gears, but the center distance is a lot smaller. Where it is necessary to have two parallel shafts rotate in the same direction, the internal gear eliminates the use of an idler gear.
Internal Gears possess several 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 almost of the same length than is the case with an exterior gear and pinion planetary gearbox having the same tooth ratio and tooth duration. Which means relative slippage of the teeth is less in the case of the internal. This aspect 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 wear, a reduction in the quantity of sliding action is definitely desirable.
Internal Gear drives may be operated with the apparatus 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 as well close in proportions to the gear, interference may result. Therefore, the difference in teeth of the pinion to the apparatus should not be less than 15.
RUSH GEARS inc. offers regular Internal Gears in STEEL, STAINLESS, CAST IRON, BRONZE, Aluminium, DELRIN and nonmetallic (PHENOLIC). We will gladly produce made to purchase Internal Gears to your requirements.