Shedding device for labelling on selvedges (S1, S2) or on fabrics on a weaving loom, the shedding device comprising: - a beam meant for extending over the loom, parallel to its weft axis; - at least a Jacquard head, the Jacquard head comprising: • selectable hooks; • driving means for moving the selectable hooks between an upper position and a lower portion, the driving means comprising a main pulley; • a harness connected to the hooks; and • a harness support for anchoring the harness; - a main shaft for driving the main pulley in rotation, the main shaft extending parallel to the beam; and - a motor for driving the main shaft, characterized in that - the Jacquard head rests, via at least one pad having a low friction coefficient with the material of the beam, on at least one supporting rib of the beam; - the main pulley is fixed in rotation with the main shaft and slidable along this shaft. - the main shaft and the main pulley are splined, with matching splines (504/2144, 506/2146), - the main shaft is inserted in a central bore of the main pulley, - the Jacquard head is provided with a quick locking mechanism for locking the Jacquard head along the beam and wherein the Jacquard head is slidable along the beam when the quick locking mechanism is not active, and - the quick locking mechanism includes a clamp reversibly movable with respect to a frame of the Jacquard head between a first locked position, where the beam is pinched between the pad and the clamp, and a second released position, where the clamp does not brake a sliding movement of the Jacquard head along the beam. - a beam meant for extending over the loom, parallel to its weft axis; - at least a Jacquard head, the Jacquard head comprising: • selectable hooks; • driving means for moving the selectable hooks between an upper position and a lower portion, the driving means comprising a main pulley; • a harness connected to the hooks; and • a harness support for anchoring the harness; • selectable hooks; • driving means for moving the selectable hooks between an upper position and a lower portion, the driving means comprising a main pulley; • a harness connected to the hooks; and • a harness support for anchoring the harness; - a main shaft for driving the main pulley in rotation, the main shaft extending parallel to the beam; and - a motor for driving the main shaft, - the Jacquard head rests, via at least one pad having a low friction coefficient with the material of the beam, on at least one supporting rib of the beam; - the main pulley is fixed in rotation with the main shaft and slidable along this shaft. - the main shaft and the main pulley are splined, with matching splines (504/2144, 506/2146), - the main shaft is inserted in a central bore of the main pulley, - the Jacquard head is provided with a quick locking mechanism for locking the Jacquard head along the beam and wherein the Jacquard head is slidable along the beam when the quick locking mechanism is not active, and - the quick locking mechanism includes a clamp reversibly movable with respect to a frame of the Jacquard head between a first locked position, where the beam is pinched between the pad and the clamp, and a second released position, where the clamp does not brake a sliding movement of the Jacquard head along the beam.