PURPOSE: To prevent wear of an elastic tube and increase its life, by forming a fitting hollowed part to the peripherally longitudinally central part of a squeeze roller and fitting an elastic pressing member to said fitting hollowed part.

CONSTITUTION: A motor is started to rotate a driving shaft 16, if a chain 18 is turned around, always at least one of the squeeze rollers 19 is moved rolling from the suction side to the delivery side of an elastic tube 12 while pressing the elastic tube 12 to a main pad 10 and intermediate pad 9. While a restoring roller 23 is moved rolling while pressing the elastic tube 12, flatly pressed by the squeeze roller 19, from its both sides to promptly restore said elastic tube 12 to cylindrical shape, in this way, slurry is sucked in a follow-up state to said squeeze roller 19. An elastic pressing member 19b is flexed slightly downward by its elasticity, and the elastic tube is prevented from damage.