Arrangement for adjusting width of fibre web

An arrangement for adjusting the width of a fibre web when water is removed from pulp suspension in an apparatus comprising two filter wires permeable to water, the filter wires having the same direction of travel and both wires being arranged to be supported by surfaces equipped with water openings and to form therebetween a gap narrowing in the direction of travel, and side parts located on both edges of the gap to prevent the pulp suspension from being extruded out of the gap in the crosswise direction thereof, openings in the upper and lower surfaces of the gap being formed such that the two surfaces comprise a solid edge part next to the side parts such that the edges of the wires extend over said solid edge parts, and means for feeding the pulp suspension into the gap between the wires in the inlet direction thereof, wherein the arrangement comprises means for feeding water into the gap to the sides thereof such that while flowing together with the pulp suspension towards the outlet opening of the gap, the supplied water pushes the pulp suspension towards the centre of the gap at least substantially as far as to the openings in the upper and lower surfaces.