| 摘要 |
A shift assembly for a two-speed transfer case (16) utilizes a single actuator to drive both the gear or speed range selection mechanism and a modulating friction clutch pack (150) which selectively transfers drive torque from a primary transfer case output (140) to a secondary transfer case output (246). The shift assembly (200) includes an actuator (202) which rotates a shift rail (204) and cam (212) having an intermediate helical track and a dwell region at each end. A lost motion assembly operating in conjunction with the helical cam selectively engages and disengages the friction clutch pack (150) when the cam follower is in one of the two dwell regions. Thus, the shift assembly (200) provides sequential operation from full clutch engagement in a first speed range through clutch disengagement in the first speed range, de-selection of the first speed range and selection of neutral, de-selection of neutral and selection of the second speed range and thence increasing engagement, up to full engagement, of the friction clutch pack (150) in the second speed range. |
