an overhead conveyor system transports a selectable workpiece from vertically extending storage racks having a plurality of horizontally extending shelves with stationary stacks of workpieces to be processed on each shelf . each shelf includes horizontally spaced shelf support members defining openings complementary to horizontally extending support members of a carriage . the horizontally extending members of the carriage are insertable between adjacent horizontally spaced shelf members to engage the upper most workpiece supported by the shelf located below the horizontally extending support members of the carriage . workpiece engaging members operably associate or engage the upper - most workpiece with the carriage for movement vertically and horizontally along the path of travel to a workstation for processing .