Patent ID: 7628727

Claim:
An automatic speed reducing ratio-switching apparatus arranged between a rotary driving source and a drive apparatus, for automatically switching a speed reducing ratio of a member, which is operated on the basis of a rotary driving force of said rotary driving source, said automatic speed reducing ratio-switching apparatus comprising: a first planetary gear mechanism and a second planetary gear mechanism including a input shaft connected to said rotary driving source, an output shaft connected to said driven apparatus, an input side sun gear and an output side sun gear, input side planet gears and output side planet gears, an input side ring gear and an output side ring gear, which are meshed with said input side planet gears and said output side planet gears respectively, and an input side carrier, an output side carrier and an intermediate carrier, which rotatably support said input side planet gears and said output side planet gears and which are rotated integrally in accordance with revolution of said input side planet gears and said output side planet gears, said first planetary gear mechanism and said second planetary gear mechanism being juxtaposed in an axial direction of said input shaft; a first inner clutch member and a second inner clutch member, each of which enables rotation in one direction while locking rotation in the other direction of said input shaft, and which have mutually different locking directions; a first outer clutch member and a second outer clutch member, each of which enables rotation in one direction while locking rotation in the other direction of said input side ring gear or said output side ring gear, and which have mutually different locking directions; and a viscous resistance member, which functions based on action of a static frictional force, so that said input side sun gear, said input side planet gears, and said input side ring gear are integrally rotated respectively in an identical direction, or so that said output side sun gear, said output side planet gears, and said output side ring gear are integrally rotated respectively in an identical direction.