Gear 1 is keyed to the driving shaft, rotates about fixed axis A and meshes with planet gears 2 which, in turn, mesh with internal gear 5, rigidly attached to hoisting drum b. Planet gears 3 are rigidly attached to gears 2 and mesh with internal gear 4, rigidly attached to hoisting drum a. Planet gears 2 and 3 are connected by turning pairs to carrier 6 which rotates freely about axis A. The speeds n₁, n₅ and n₄ of gear 1,and drums b and a (in rpm) are related by the equation n₁=n₅z₅/z₁(z₁z₃-z₂z₄)/(z₃z₅-z₂z₄)+z₄/z₁(z₂z₅-z₁z₄)/(z₃z₅-z₂z₄) where z₁, z₂, z₃, z₄ and z₅ are the numbers of teeth of gears 1, 2, 3, 4 and 5. The mechanism permits various modes of operation in hoisting. If drum b is braked, a load can be hoisted by drum a and vice versa. If one of the drums is rotated by the action of a descending load, the other drum can hoist a load, etc.
$2954$CxG,MH$