Single actuator lost motion shift assembly

A lost motion shift assembly comprising, in combination,

• a first clutch for selectively driving a first output from one of two drive members,
• a shift rail having at least one cam follower disposed thereupon,
• a motor for bi-directionally rotating said shift rail,
• a shift fork disposed on said shift rail and defining at least one cam in cooperating relationship with said cam follower, said cam defining a pair of dwell regions and an intermediate helical region,
• a second clutch for providing modulating engagement between said first output and a second output,
• a lost motion mechanism including a projection on said shift rail and a drive member disposed on said shift rail and having a pair of spaced-apart shoulders engageable by said projection, and
• an actuator coupled to said drive member and adapted to actuate said second clutch,
• whereby said first clutch is translated between said two drive members while said projection moves between said pair of shoulders and said second clutch is actuated while said follower engages one of said dwell regions of said cam.

A transfer case for a motor vehicle comprising, in combination,

• an input shaft,
• a speed reduction assembly driven by said input shaft and configured to provide a first, direct drive output and a second, reduced speed output,
• a first output member adapted to drive a first vehicle driveline,
• a second output member adapted to drive a second vehicle driveline,
• a first clutch for selectively engaging said first output member with one of said outputs of said speed reduction assembly,
• a second clutch for providing modulating engagement between said first output member and said second output member,
• a rotatable shift rail having at least one cam follower,
• a drive assembly for bi-directionally rotating said shift rail,
• a shift fork adapted to translate said first clutch, said shift fork disposed adjacent said cam follower and defining at least one cam having helical and dwell regions,
• a clutch actuator adapted to generate and apply compressive force to said second clutch, and
• means driven by said shift rail and adapted to activate said clutch actuator when said cam follower is in a dwell region of said cam and to release said actuator when said cam follower is in a helical region of said cam.