Patent ID: 8821333

Claim:
A planetary gear mechanism comprising: a first member; a second member that includes an internally toothed gear formed in an inner circumferential surface thereof and that is rotatable relative to the first member about an axis of input and output shafts; an oscillating member that is formed in an annular shape and that includes an externally toothed gear formed in an outer circumferential surface thereof to mesh with the internally toothed gear, a number of teeth of the externally toothed gear being less than a number of teeth of the internally toothed gear, the oscillating member being formed so as to oscillate relative to the second member so that only a circumferential portion of the externally toothed gear meshes with the internally toothed gear, and the oscillating member being able to oscillate relative to the first member while rotation thereof relative to the first member is restricted; and a third member including an eccentric portion, a center of an outer circumferential surface of the eccentric portion being displaced from the axis of input and output shafts, and the eccentric portion being operable to rotate about the axis of input and output shafts while supporting an inner circumferential surface of the oscillating member, thereby to oscillate the oscillating member, or being rotated about the axis of input and output shafts due to oscillation of the oscillating member, wherein a driving force is applied to the third member to oscillate the oscillating member and to move a circumferential position at which the externally toothed gear and the internally toothed gear mesh with each other, so that the driving force is delivered at a reduced speed to at least one of the first member and the second member, or the driving force is applied to at least one of the first member and the second member so as to move the circumferential position at which the externally toothed gear and the internally toothed gear mesh with each other, and oscillate the oscillating member, so that the driving force is delivered at an increased speed to the third member, wherein: a first pin protrudes from one of the oscillating member and the first member in a direction of the axis of input and output shafts; and one of the oscillating member and the first member includes an insert hole into which the first pin is inserted, so that rotation of the oscillating member relative to the first member is restricted via the first pin, wherein the externally toothed gear is formed by a plurality of second pins that protrude from the oscillating member in the direction of the axis of input and output shafts, and wherein: the oscillating member includes a first side face and a second side face that face in opposite directions in the direction of the axis of input and output shafts, the first pin protrudes from the first side face of the oscillating member, and the second pins protrude from the second side face of the oscillating member, and the first pin and the second pins are formed on the same circumference.