Suction duct for the pneumatic removal of fiber tufts detached by a bale opener

In a fiber bale opener including a downwardly open housing adapted to be supported above fiber bales to be opened and accommodating an opening roller having an axis and being arranged for detaching fiber tufts from upper bale surfaces and a suction duct through which fiber tufts detached by the opening roller are adapted to be removed by a suction air stream flowing therethrough;

• said suction duct being bounded by two lateral walls facing one another and being spaced from one another in a direction parallel to said axis;
• one said lateral wall having an upwardly extending first oblique air guiding face and the other lateral wall having an upwardly extending second oblique air guiding face;
• the improvement wherein said first oblique air guiding face projects into said suction duct to an extent of between one fourth and one third of a width dimension of said suction duct measured parallel to said axis at a location adjacent said opening roller and further wherein said second oblique air guiding face has a lower guiding face part arranged generally symmetrically to said first oblique air guiding face relative to an imaginary center plane of said suction duct oriented perpendicular to said axis whereby travelling paths of air streams from opposite longitudinal ends of said opening roller towards said center line are of approximately equal length;
• and further wherein said second oblique air guiding face has an upper guiding face part adjoining an upper end of said lower guiding face part and extending upwardly therefrom at an orientation different from that of said lower guiding face part.