I think everyone has gear interference when using internal gears, which will cause internal components to fail, but why does this phenomenon occur? We still have to understand the lower internal gear. First of all, we must understand that the internal gear is divided into an external gear and an internal gear, which are all meshing with each other. Next, I will tell you why the meshing interference of the internal gear occurs.

1. Involute Interference

In the internal meshing transmission, when the tooth tip of the internal gear exceeds the theoretical meshing limit point N1 of the gear, involute interference will occur, which is essentially the same as the involute interference of external meshing.

2. Overlapping interference of involute tooth profile

In a pair of internal gear transmission, if the difference in the number of teeth ((z2-Z1) is small, the phenomenon that the tooth profiles that are not in the meshing area may overlap with each other, that is, the pinion after meshing exits the internal gear slot. The tooth profile overlap interference occurs on the tooth top of the gear; the gear pair with such tooth profile interference cannot realize transmission (see Figure 2-7). The interference phenomenon of the tooth tip of the internal gear.

3. Radial interference

When assembling the internal gear pair, sometimes the external gear can only be inserted into the internal gear in the axial direction, and the external gear cannot be installed in the meshing position with the internal gear in the radial direction. The external gear installed in the meshing position in the axial direction cannot withdraw from the ring gear of the internal gear in the radial direction. This phenomenon is called radial interference. When the gear shaper cutter is used to process the internal gear, the radial interference will cause the top cut of the gear shaper cutter during the radial feed.