Wave generator 1 is designed as two conical members a, facing each other, around which balls 4 roll. The axes b of the balls form angles of 120°. Generator 1 rotates about fixed axis A. Flexible (radially deflectable) ring gear 2, having teeth on its outside circumference, rotates about fixed axis B and meshes at three symmetrically located areas with teeth of circular internal ring gear 3, which is rigidly attached to the base, i.e. fixed. A large number of teeth are simultaneously in engagement in areas which are symmetrical with respect to axes b. The transmission ratio from wave generator 1 to link 2 is i₁₂=ω₁/ω₂=n₁/n₂=-z₂/3 where ω₁, ω₂, n₁ and n₂ are the angular velocities and speeds (in rpm) of generator 1 and link 2; and z₂ is the number of teeth of link 2, which is equal to z₂=z₃-3.
$2931$CxG,SW$