Press method in a paper machine

A method in a paper machine press section for dewatering a wet paper or paperboard web by threading the web through at least three nips of the press section, the web being supported by the surface of a felt or a roll at all times, comprising the steps of:

• detaching the web from the paper machine forming wire by means of a first felt loop and a pick-up roll operating within said first felt, and adhering the web onto the lower outer surface of said first felt loop by means of suction prevailing in the suction sector of said pick-up roll;
• transferring the web which adheres to the lower surface of said first felt loop primarily by adhesion forces and without any substantial support from below to a first dewatering press nip of the press section which nip is formed by and between an upper foraminous suction roll and a second water receiving lower roll;
• threading a second felt loop into the first dewatering press nip so that said second felt comes into contact with the web adhered on the first felt not until substantially in region of said first press nip;
• pressing the web in the first dewatering press nip between the first felt and the second felt while applying between the press rolls a first linear pressure to dewater the web simultaneously in two directions through both sides of the web;
• detaching the web from contacting the second felt by means of suction prevailing inside said upper suction roll;
• treating the second felt after having left the first nip by felt conditioning means and threading it back to the first nip in said manner;
• adhering the web by suction on the surface of the first felt wrapping said suction roll on a sector following the first nip, said sector corresponding to a central angle of 90 to 160 degress of the suction roll and so transferring the web to a second dewatering press nip formed by said suction press roll and by a smooth surface plain press roll;
• pressing the web in said second nip using a second linear pressure so as to dewater the web through the one side facing the first felt;
• detaching the web from the first felt utilizing the adhesion force of the surface of said plain press roll and adhering the web on last mentioned surface;
• treating the first felt after having left the second nip by its felt conditioning means and threading the first felt back to wrap said pick-up roll;
• transferring the web adhered on the surface of said plain press roll, to a third nip formed by said plain press roll and a fourth press roll which fourth roll is a water receiving roll so that the travel of the web while proceeding adhered to the plain roll surface from the second nip to the third nip corresponds to a central angle of 70-160 degrees of the plain roll;
• threading a third felt into said third nip and pressing the web in said third dewatering press nip using a third linear pressure so as to dewater the web through its one side facing the third felt;
• and
• transferring the web, which beginning from the second nip, is continuously adhered to the surface of said plain press roll after said third nip, to a following web processing phase.