Gear 1 is keyed to the driving shaft, rotates about fixed axis A and meshes with planet gear 2 which is rigidly attached to planet gear 3. Gear 3 meshes with internal gear 4 which is rigidly attached to drum 9 of the pulley block. Drum 9 rotates about axis A. Internal gear 7 is rigidly attached to drum 9 and meshes with gear 6 which rotates about fixed axis B. Gear 6 meshes with gear 5 which is rigidly attached to carrier 8. Carrier 8 is connected by a turning pair to planet gears 2 and 3. The speeds n₁ and n₉ of gear 1 and drum 9 (in rpm) are related by the equation n₉=n₁(z₁z₃z₅)/(z₂z₄z₇-z₂z₄z₅+z₁z₃z₇) where z₁, z₂, z₃, z₄, z₅ and z₇ are the numbers of teeth of gears 1, 2, 3, 4, 5 and 7.
$2955$CxG,MH$