suction-box

from The Century Dictionary.

• noun In paper-making, a chamber in which there is a partial vacuum, placed below the web of pulp to assist in removing the water from it.
• noun The chamber below the inlet-valves of a pump into which atmospheric pressure forces the water or other liquid when the pressure above the valves is made less by the suction stroke of pistons or plungers. The water or liquid goes through the inlet valves from the suction-box.