Agitator with a rotary shaft and hollow shaft for stirring and mixing materials

An agitator, which comprises:

• a first and second hollow shaft which are coaxial, said second shaft extending from a distal end of said first shaft;
• a rotary shaft positioned within said first and second hollow shafts;
• a first and a second stirring rotor which are coaxial and are positioned at a distal end of said rotary shaft and said second hollow shaft, respectively;
• an electric motor disposed at an end portion of the rotary shaft, said motor having a casing, a rotor and a stator wherein said motor drives the first hollow shaft;
• a gear reduction mechanism which includes a rotary member, said gear reduction mechanism being driven by said first hollow shaft and being positioned in said casing for engaging said rotary shaft, wherein a portion of the rotary shaft extends within the casing and is rotatably received in said first hollow shaft and wherein said gear reduction mechanism includes means for rotating said rotary member at a speed which is lower than that of the first hollow shaft;
• and
• bearing members for journaling the rotary shaft at upper and lower ends of the casing, wherein the rotor of the electric motor is fixed to a middle portion of the first hollow shaft, and the rotary shaft and the first hollow shaft are interlocked with each other by said gear reduction mechanism.