Power drive mechanism for a motor vehicle liftgate having a disengageable gear train

A power drive mechanism for providing power assisted opening and closing of a liftgate pivotally mounted on a vehicle, said vehicle including a body controller to control operation of said power drive mechanism, said liftgate including a power operated latch assembly capable of latching engagement with a striker on the vehicle to releasably latch said liftgate and of power operated unlatching movement, said power drive mechanism comprising:

• a mounting bracket mountable on a “D” pillar of said vehicle;
• a linking arm pivotally connected with the liftgate;
• a crank arm pivotally mountable on the mounting bracket and pivotally connected with the linking arm;
• a gear train pivotally mounted on said mounting bracket;
• a drive motor mounted to said mounting bracket, said drive motor operatively connected with said crank arm through said gear train, said gear train being movable between an engaged position and a disengaged position, said engaged position effecting a driving engagement between the drive motor and the crank arm such that energizing said drive motor drivingly rotates said crank arm to responsively effect said opening and closing of said liftgate and said disengaged position disengages said drive motor from said crank arm permitting movement of said crank arm without backdriving said drive motor;
• an actuator operatively connected with said gear train and being operable to effect said movement of said gear train;
• a bracket assembly operatively connected with said gear train;
• a holding linkage operatively connected between said gear train and said actuator to maintain said driving engagement once said actuator moves said gear train into the engaged position, said holding linkage comprising a holding link and a connecting link, said holding link pivotally connected with said bracket assembly and said connecting link, said actuator includes a pivotally mounted actuating link pivotally connected to said bracket assembly and said holding link;
• a switch mounted on said mounting bracket and switchable in response to movement of the crank arm for indicating open and closed conditions of the liftgate;
• an electronic control unit electrically communicating with said body controller, said latch assembly, said drive motor, said switch and said actuator;
• and
• a fixedly mounted pin, said holding link includes a slot having a holding notch, said holding link slidably receiving said pin in said slot for guiding movement of said holding link, such that when said holding link engages said pin in said holding notch, said holding linkage maintains said engaged position of said gear train.