Abstract: A plural speed planetary gear box has an input member and output member coupled together directly by a shiftable coupling sleeve or coupled together indirectly by a planetary gear set. The shift from direct to indirect coupling involves shifting the coupling sleeve out of direct coupling position between the input and output members to a different position in which the input member is coupled to one portion of the planetary gear set and the output member is coupled to another portion of the planetary gear set. A hydraulically actuated piston drives the coupling sleeve through a resiliently loaded lost motion isolator which applies a first force to the coupling sleeve for disengagement, and also applies a second force to the coupling sleeve to produce meshing engagement with the input member or with the planetary gear set element.