63 Frame to 90S Frame - Motor body in aluminium 90L Frame to 180M Frame - Motor body in aluminium / cast iron 200L Frame to 250M Frame - Motor body in cast iron End shields made of aluminium / cast iron Cylindrical shaft made of 45C8 / SS 410 Rotors are pressure die cast and dynamically balanced with shaft and key Stator core pack is built from low loss electrical grade steel lamination Terminal box rotation in steps of 900 Cooling fan made of nylon / aluminium material and designed for better cooling Cooling fan cover made of sheet metal