23 MACHINES FOR THE PRODUCTION OF SINGLE OR MULTI-PLY BOARDS OR PANELS OR OTHER FORM BODIES FROM CHIPS OR FIBERS OF WOOD; BELT, ROLLER AND CHAIN CONVEYORS; AND MECHANICAL, PNEUMATIC AND HYDRAULIC PROCESS CONTROL APPARATUS INCLUDING APPARATUS FOR CONTROLLING THE WEIGHT AND THICKNESS OF THE BOARDS OR PANELS AND PARTS THEREOF; AS WELL AS PLANTS COMBINING SAID MACHINES, CONVEYORS, AND CONTROL APPARATUS