Patent ID: 7712390

Claim:
A ball type speed reducer device comprising: a follower wheel secured to an output shaft which is rotatably disposed within a housing; a plurality of follower balls rotationally placed in cavities which are provided on an outer periphery of said follower wheel at regular intervals in a circumferential direction; an input shaft having a cammed streak portion, both sides of which have a first engagement surface and a second engagement surface with which said follower balls come to engage, said input shaft being orthogonal with said output shaft; among said follower balls, at least four balls being on said input shaft, a first part of said balls situated on a first end side of said input shaft and a second part of said balls situated on a second end side of said input shaft being placed in such a direction as to approach each other; the first part of said balls situated on said first end side of said input shaft always engaging tightly with the first engagement surface; and the second part of said balls situated on said second end side of said input shaft always engaging tightly with the second engagement surface.