a mesh - belt conveyor for conveying materials into industrial furnaces comprises a conventional continuous mesh - belt wound at one end around an idle reversing roller and engaged at its other end in a labyrinth device subjected to a reciprocating motion in the general direction of the conveyor , the belt being also intermittently clamped , close to the reversing roller , by a gripping device which produces intermittent movements of the belt toward the reversing roller in alternation with the movements of the labyrinth device , in order to cause an intermittent advance of the belt .