To prevent contamination in a cleaning chamber 12 due to a press releasing means 7 for separating a sliding surface between a distributor 52 and a rotor 24.

The rotor 24 is fixed to a rotary wheel 10 attached to a main shaft 4 and a stator 40 and the distributor 52 connected to the stator 40 are arranged thereabove. In a normal production operation, the distributor 52 is brought into press contact with the rotor 24 by a spring 46. A through-hole is formed at the center of the main shaft 4 an the rotary wheel 10 and a slide shaft 70 is inserted. The slide shaft 70 is vertically moved by an air cylinder 78 mounted outside the cleaning chamber 12. The upper end of the slide shaft 70 is connectable to the stator 40 through a bush rod 84 and a bush plate 60 and at the upward movement of the slide shaft 70, the stator 40 is pushed up and the distributor 52 is separated from the rotor 24.