Lift assist system for vehicle tailgates

A vehicle tailgate lift assist system, comprising:

• a) a vehicle tailgate adapted to open and close by rotating about a tailgate pivot axis in relation to a vehicle body;
• b) coupling means to releasably connect the vehicle tailgate and the vehicle body;
• c) an energy storage device located within the vehicle body and adapted to be pivotally anchored at a first end to the vehicle body;
• d) a crank arm pivotally attached to a second end of the energy storage device and rigidly attached to an actuation shaft that is coaxially aligned with the tailgate pivot axis;
• e) a pivot bracket assembly comprising a mounting bracket fixed to the vehicle body and holding a pivot bearing arrangement to facilitate a rotary joint about the tailgate pivot axis;
• f) wherein the pivot bearing arrangement comprises a unitary component overmolded on a pivot sleeve to act as a bushing between the actuation shaft and the pivot sleeve, and the overmolded bushing sealably engages the crank arm at one end of the overmolded bushing and the actuation shaft at the opposite end of the overmolded bushing;
• such that relative rotary motion of the tailgate and the vehicle body results in linear extension of the energy storage device and maximum energy storage at the tailgate fully open position.