<p>The mechanism comprises outer and inner distributor cylinders, located coaxially. Liq. inlet pipe around which the whole assembly rotates, and which is connected to the inside of the inner cylinder. The space between the outer and inner cylinders is connected to the inside of the inner cylinder at the top end of the inner cylinder. The inside of at least one distributor arm is connected to the inside of the inner cylinder. The inside of at least one of the other distribution arms is connected to the space between the inner and outer distributor cylinders.</p>
