Patent ID: 6890281

Claim:
A speed reduction device for preventing a rotational back-rush, said device comprising: a rotary plate in which an internal gear is formed provided at the inside of a generally square casing, said square casing adapted to be closed by a cover; an external gear disposed in eccentrically tooth-coupling relation with said internal gear, said external gear coupled on an output shaft that is installed on said square casing and said cover; operational grooves disposed at right and acute angles to said internal gear and said output shaft, at the outside of said rotary plate; eccentric shafts provided in said operational grooves to correspond to the eccentric quantity generated between said internal gear and said external gear, said eccentric shafts coupled to said square casing and at the same time driven by bevel gears coupled to end portions thereof; an input shaft extended from any one of said eccentric shafts to the outside of said square casing, to which power transmission is made; and eccentric parts provided in said eccentric shafts, said eccentric parts, at the time of being rotated in the respective operational grooves, constructed in such a manner that when said eccentric part of said eccentric shaft pushes said rotary plate to said output shaft side or to the opposite side to said output shaft, said eccentric part of said eccentric shaft serves to guide said rotary plate.