as represented by the measured speed line of fig7 fig5 represents in the speed versus torque characteristic of a motor and its driving apparatus which is enhanced to improve motor speed change the slope of the line between points a 1 and b 1 on fig5 results in a change of speed of approximately 47 to 48 rpm per inch pound of torque thus making speed changes more easily detected a characteristic as shown in fig5 can be achieved by producing a motor with the appropriate parameters fig8 a and 8b are views of a field winding stator of an induction motor fig9 a and 9b represent the induction rotor of such a motor the rotor of an ac induction motor includes a plurality of ferris metal rotor lamination formed together into a cylinder as represented at 62 the rotor laminations have a plurality of regularly spaced apertures which are arranged to extend from one end of the rotor cylinder at an angle as represented by 64 the apertures are filled with an electrically conductive non ferris metal such as aluminum finally end rings 64 are formed at the ends of the diagonal conductive lines 64 from non ferris electrical conductors to provide conductive paths between the diagonals 64 due to current induced by ac applied to the field coils magnetic fields are.