Abstract: A planetary gear assembly comprising a primary array (2) of co-axial planetary gear sets and a secondary array (3) of co-axial planetary gear sets, planetary gear set being provided with an associated gear engagement means (21), the arrangement being such that in use each planetary gear set and the associated gear engagement means are arranged for relative translational movement which is substantially parallel to the axis of the respective array of planetary gears and a rotational input drives a selected primary gear set which is engaged with the associated gear engagement means, the rotational output of the engaged primary gear set (2) being transmitted through the associated gear engagement means (21) to gear engagement means which is engaged with the associated selected secondary gear set (3), the output from the selected secondary gear set being transmitted to rotational output means (18, 49).

Abstract: The size, weight, and cost of a full-traction differential are significantly reduced by the synergism of several interrelated design features of a cartridge-like gear complex: (1) Each combination gear has only a shallow journal hole in each end of an otherwise solid gear body, being supported on mating hubs fixed to mounting plates slipped into a one-piece differential housing. (2) The solid worm-wheel portion of the combination gears has a deeper hour-glass shape. (3) Mating worm/worm-wheel teeth have a broad “supra-enveloping” contact pattern on only the drive side of the mesh. (4) The side-gear worms have closed-end teeth. (5) Both diameter and axial length of the side-gear worms are reduced by a special cutting process. The efficiency of the differential is increased by a thrust plate supported in the mounting plates and positioned between inner ends of the side-gear worms.