126 which in turn causes follower segment 136 to move within spiral groove 132 until shift collar 84 is located in its h position at this position follower segment 136 enters high range dwell groove 128 which permits continued rotation of drive shaft 120 in the first direction while shift collar 84 is retained in its h position with the high range drive connection established between input shaft 60 and annulus gear 90 thereafter rotation of driveshaft 120 and range cam 126 in the opposite second direction causes follower segment 136 to exit high range dwell groove 128 and re enter intermediate spiral groove 132 for causing shift collar 84 to begin moving from the h position toward its l position upon continued rotation of range cam 126 in the second direction follower segment 136 exits spiral groove 132 and enters low range dwell groove 130 for locating shift collar 84 in its l position and establishing the low range drive connection between planet carrier 70 and annulus gear 90 clutch actuator assembly 124 is also driven by motor assembly 58 and includes a ball ramp unit 140 and a gear assembly 142 ball ramp unit 140 includes a first ball ramp plate 144 a second ball ramp plate 146 and a plurality of balls 148 disposed in ramped grooves 150 and 152 formed in corresponding face surfaces of plates 144 and 146 first ball ramp plate 144 is non rotatably secured to housing 66 and is supported for bi directional axial movement specifically first ball ramp plate 144 is shown to coaxially surround rear output shaft 40 and is arranged to move axially for exerting an axially directed clutch engagement force on apply plate 114 for frictionally engaging clutch pack 109 a thrust bearing is shown located between.