EXTENDED FIBROUS WEB PRESS NIP STRUCTURE WITH CONTOURED LEADING AND TRAILING SILLS

A press structure and method for pressing a traveling fibrous web such as a web of paper received from the forming section of a paper machine including a pair of looped traveling impervious belts which come together in a pressing zone and pass the fibrous paper web through the pressing zone against a traveling felt. The belts are urged toward each other by fluid pressure chambers outwardly of the belts and the chambers have side walls which are sealed to the belt at their edges, and the side walls have a leading sill on the oncoming side and a trailing sill on the offrunning side with the leading sill contoured to provide a gradual increase in pressure over a period of time to avoid crushing of the fibers and with a trailing sill on the offrunning side which is short and flat to obtain a sudden drop of pressure at the end of the pressing zone.