Importance

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Abstract

A piston and geared rack assembly are moved by pressurized air in opposite directions within a power cylinder housing as the vehicle operator registers door closing and opening commands in a solenoid valve. This lateral movement is converted to rotary movement by a pinion gear driven by the rack and coupled to turn a spindle shaft which drives the door. At full stroke during door closing, the power piston actuates a valve to charge the lower chamber of an auxiliary cylinder to move a lift piston rod, movable within the spindle shaft, to raise the closed door into a locked position. Upon a door-open command, the solenoid valve exhausts the charged cylinder chambers, admits air into the upper chamber of the auxiliary cylinder to move the lift piston and rod to lower and release the door, and slowly charges the associated opening chamber. This enables the delayed movement of the power piston and rack assembly in the opposite direction, reversing the rotation of the pinion and spindle shaft, to open the door. If air pressure is lost with the door closed and locked, the weight of the door forces the lift piston and rod down, releasing the door from its locked position for emergency manual operation.

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First Claim