To reduce the noise generated when the planetary gear assembly is driven.

In a two-speed planetary gear assembly and a zdouble disengaging mechanism for a transfer case of an automobile or a similar device, a reduction assembly is completely disengaged from a power route, when a neutral or high speed gear rate (typically direct drive) is selected. The double disengaging mechanism comprises a clutch collar 146 slidable in an axial direction. The clutch collar is freely rotatable in a hub 120 for reduction movable corresponding thereto. By selectively translating the hub for reduction, a direct drive member or an input 62 is engaged with a planetary gear assembly 90. When the hub for reduction, is positioned to be engaged with the input part of the planetary gear assembly, a gear 112 set on a carrier 110 of the planetary gear assembly, is engaged with the hub for reduction. Whereby the hub for reduction 120 and an output member 70 are decelerated and driven.