Wave generator 1 is a cam of elliptical shape and rotates about fixed axis A. The flexible (radially deflectable) link consists of external ring gear 2 and internal ring gear 4, rigidly attached to (or integral with) each other, with numbers of teeth, z₂ and z₄, that differ only slightly. Flexible ring gear 2 meshes at two opposing areas with circular internal gear 3 which is rigidly attached to the base, i.e. fixed. Flexible internal ring gear 4 meshes at two opposing areas with circular external gear 5 which rotates about fixed axis B. The transmission ratio from wave generator 1 to gear 5 is i₁₅=ω₁/ω₅=n₁/n₅=-(z₃z₅)/(z₃+z₅+2) where ω₁, ω₅, n₁ and n₅ are the angular velocities and speeds (in rpm) of generator 1 and gear 5; and z₃ and z₅ are the numbers of teeth of gears 3 and 5, which are equal to z₃=z₂+2 and z₅=z₄-2.
$2928$CxG,SW$