has an end cap 9 the bearing associated with the cover has an end cap 8 the bearings 4 assist in maintaining proper alignment of permitting free rotation of a stainless steel drive shaft 6 the end of the shaft can be coupled to a motor or power takeoff in a conventional manner neither a motor nor power takeoff are shown the drive shaft 6 is used to impart rotational motion to a rotor 5 the rotor is comprised of two pieces a rotor insert 20 and a rotor body 22 the rotor insert 20 is preferably made of stainless steel and is keyed as is the drive shaft 6 so that a stainless steel key 7 can be used to couple the rotor 5 to the drive shaft 6 after the rotor 5 has been placed on the drive shaft the outside of the rotor insert 20 and the inside of the rotor body 22 are shaped such that rotational motion imparted to the rotor insert 20 by the drive shaft 6 is conveyed to the rotor body without any appreciable slippage in fact the rotor body 22 can be molded around the rotor insert 20 the rotor body 22 includes a front wall 24 a back wall 26 and a side wall 28.