Abstract: Control of the flow of fibrous material and selective shearing the material at predetermined lengths is provided by apparatus including a first shear element having an aperture in a plane face thereof and adapted with an input tube for feeding the fibrous material through the aperture in the shear element. A second shear element is rotatably attached to the first shear element and has an aperture in a plane face thereof alignable with the aperture of the first shear element. An egress tube is attached to the second shear element for receiving material from the aperture in the second shear element when aligned with that of the first shear element. The fibrous material is moved through the input tube and out of the egress tube by air pressure when the apertures in the shear elements are aligned. By rotating the first shear element relative to the second shear element, the fibrous material passing through the apertures therein is sheared and the flow of material therethrough stopped.