A machine for the finishing treatment of a textile web comprising [a] first and second accumulation chambers (4, 6) for accumulating said web with first and second take-up areas (8, 10) for taking up said web, [b] a conveyance duct having a length extending between first and second ends (14, 16), said duct communicating said first and second chambers (4, 6) with one another, said duct being configured so that, during treatment, said web is conveyed inside said duct widthwise, [c] said duct comprising at least first and second gas inlets (22, 24), and said machine further comprising [d] gas drive means functionally connected with said duct so that, during treatment, a gas is insufflated inside said duct in an alternating manner through said first and second gas inlets (22, 24), and with said first gas inlet being oriented such that, during treatment, said gas circulates towards said second chamber, and with said second gas inlet being oriented such that, during treatment, said gas circulates towards said first chamber, and [e] at least one impact element (2, 36, 38) arranged so that, during treatment, said web impacts said at least one impact element (2, 36, 38), and [f] said first gas inlet is provided inside said duct, at said first end and in a position adjacent to said first chamber in the first third of the length of said conveyance duct, and said second gas inlet is provided inside said duct, at said opposite second end of said duct and adjacent to said second chamber in a position of said duct that is mirror-symmetrical to said first gas inlet, characterized in that [g] said at least one impact element comprises at least one first impact element which is arranged inside said conveyance duct between said first and second gas inlets (22, 24), said first impact element being movable between: [i] a passage position of said web, in which, during treatment, said first impact element is arranged such that said web passes freely through said duct without impacting said first impact element, and [ii] an impact position of said web, in which, during treatment, said first impact element is arranged such that said web passes through said duct impacting said first impact element. [a] first and second accumulation chambers (4, 6) for accumulating said web with first and second take-up areas (8, 10) for taking up said web, [b] a conveyance duct having a length extending between first and second ends (14, 16), said duct communicating said first and second chambers (4, 6) with one another, said duct being configured so that, during treatment, said web is conveyed inside said duct widthwise, [c] said duct comprising at least first and second gas inlets (22, 24), and said machine further comprising [d] gas drive means functionally connected with said duct so that, during treatment, a gas is insufflated inside said duct in an alternating manner through said first and second gas inlets (22, 24), and with said first gas inlet being oriented such that, during treatment, said gas circulates towards said second chamber, and with said second gas inlet being oriented such that, during treatment, said gas circulates towards said first chamber, and [e] at least one impact element (2, 36, 38) arranged so that, during treatment, said web impacts said at least one impact element (2, 36, 38), and [f] said first gas inlet is provided inside said duct, at said first end and in a position adjacent to said first chamber in the first third of the length of said conveyance duct, and said second gas inlet is provided inside said duct, at said opposite second end of said duct and adjacent to said second chamber in a position of said duct that is mirror-symmetrical to said first gas inlet, [i] a passage position of said web, in which, during treatment, said first impact element is arranged such that said web passes freely through said duct without impacting said first impact element, and [ii] an impact position of said web, in which, during treatment, said first impact element is arranged such that said web passes through said duct impacting said first impact element.