Crank 1 rotates about fixed axis A of shaft b and is connected by a turning pair to gear 3. Gear 3 has four symmetrically located round holes d of a radius equal to the throw of crank 1 plus the radius of its pin. Pins c are rigidly attached to fixed housing 4 and enter holes d. Pins c are of the same diameter as crankpin 1. Thus, the dimensions of the mechanism satisfy the conditions A͞B=D͞C and A͞D=B͞C. Figure ABCD is a parallel-crank linkage. Identical linkages are formed by the otner pins c and holes d. Since gear 3 is the connecting rod of linkage ABCD, it has circular translational motion and all of its points describe circles of radius A͞B. Gear 3 meshes with internal gear 2 which is rigidly mounted on shaft a and rotates about axis A. The speeds n₁ and n₂ of crank 1 and gear 2 (in rpm) satisfy the condition n₂=n₁(z₂-z₃)/z₂ where z₂ and z₃ are the numbers of teeth of gears 2 and 3. Shafts a and b rotate in the same direction. If there is only a small difference between the numbers of teeth z₂ and z₃ the reducing gear transmits rotation with a very high transmission ratio.
$2880$CxG,PR$