low speed and for rotational speed control of the rotor or ring 156 thereof an electro magnetic drive mechanism is provided the purposes function constructional arrangement and manner of operation are described in full detail in my u s pat no 4 593 215 issued jun 3 1986 the electro motive drive mechanism is essentially a pair of side by side conventional polyphase induction motors the armature windings 130 are installed in an arcuate recessed housing portion 132 of the lower portion 38 of the repressor casing and firmly fastened in position in the peripheral sense the windings 130 and their magnetic cores 133 extend only as a partial semicircle the electro magnetic rotor 134 is fabricated as a side by side pair of rings 136 inset into the repressor rotor or ring 156 and firmly attached thereto in registry with the stationary armature electro magnetic circuitry comprising windings 130 and magnetic cores 133 interjacent recesses 138 in the armature housing 132 and repressor rotor 156 are filled with high temperature particulate iron epoxy platic 140 which laterally encloses and anchors windings 130 cores 133 and rings 136 in place polyphase electric current is led into the armature section by electrically insulated leads 142 as shown in fig8 and in more detail in u s pat no 4 593 215 the disposition of the armature windings 130 provides for opposed magnetic polarities to provide opposed induced rotor currents which serve to oppose the setting.