Internal gear 1 rotates about fixed axis A-A and meshes with external planet gear 4 which is rigidly attached to internal gear 5. Planet gear 5 meshes with gear 6 which rotates about axis A-A. Carrier 2, designed as a hollow journal, is rigidly attached to gear 3 which meshes with gear 7. Gear 7 rotates about fixed axis B. The speeds n₁, n₇, and n₆ of gears 1, 7 and 6 (in rpm) are related by the equation n₇=(z₃/z₇)((z₁z₅n₁-z₄z₆n₆)/(z₄z₆-z₁z₅)) where z₁, z₃, z₄, z₅, z₆ and z₇ are the numbers of teeth of gears 1, 3, 4, 5, 6 and 7.
$2901$CxG,DR$