Teaching model for reduction gearbox of small-tooth-difference transmission door roller

The utility model relates to a teaching model for a reduction gearbox of a small-tooth-difference transmission door roller. The teaching model comprises a base and the reduction gearbox. The reductiongearbox comprises a left end cover, a right end cover, an output shaft and a working cavity; the left end cover and the right end cover are both made of transparent materials. An inner gear ring is arranged in the working cavity, the left end of the inner gear ring and the right end of the output shaft are connected into a whole, a concave bearing seat is arranged in the center of the inner gearring, an input shaft rotationally connected with the bearing seat and the right end cover through bearings is arranged between the bearing seat and the right end cover, and a hand crank is arranged atthe end of the input shaft; the input shaft is of a double-eccentric-shaft structure forming an angle of 180 degrees with each other, and two planet wheels are arranged on the double-eccentric-shaftstructure and are respective