"Jim as you said, 'assuming Fourdrinier technology' and assuming that dryer section length is proportional to output speed, the rest of the machine is not proportional to output for a couple of reasons.  The first is cantilevering requirements imposed on the Fourdrinier by added components for dewatering. The proportional increase in mass for the cantilever beams is far less than the increase in output capacity.  The same applies to press sections.  Now if both sections used seamed wires, then the increase in mass would be close to proportional but the initial weights would be far lower to start with.  Same thing for the press section.  The reason weight increase is the higher mass of the rotating components due to critical speeds.