PURPOSE: To control abnormal oscillation amplitude for a wide range, by absorbing the unbalance of materials to be dehydrated contained in the rotary tank with the liquid balancer and ball balancer installed at the upper part of tank and absorbing the load with the balancer installed at the lower part of tank.
CONSTITUTION: Annular case 22 is concentrically installed at the upper end part of rotary tank 20 made of plastic. Case 22 is divided into two parts, the upper and lower parts. Liquid balancer part 23 is provided in the upper part and ball balancer part 25 is provided in the lower part, and thus upper balancer part 21 is formed. In this way, the oscillation amplitude of the upper part of rotary tank 20 is controlled so that the amplitude is always small for the change of a wide range of unbalancing extent. Moreover, the second ball balancer part 28 is provided at the bottom of rotary tank 20, by forming annular case at the periphery of bottom surface of rotary tank 20. In this way, the oscillation amplitude at the lower part of tab can be controlled effectively even when an unbalanced load is applied to the lower part, and low-noise and low-oscillation can be achieved on the whole.