US Patent 7162762 Dock leveler with inflatable bag

An air operated dock leveler is provided to selectively raise and lower a deck with an extendable lip. The deck includes a downwardly extending deck lift arm. An air lift assembly includes a single chamber, inflatable bag positioned between a stationary lower bag support and movable upper platform. A pull line is secured to the platform and the deck lift arm. When actuated, a blower inflates the bag and raises the platform. The pull line pulls the deck lift arm forward and raises the deck to an inclined position. When the blower is turned off, the ramp descends until the now extended lip engages the bed of a truck. After loading or unloading the trailer, the bag is reinflated to raise the ramp and retract the lip. The blower is then turned off, and the ramp descends to its stored position.