Abstract: The rotor core of an armature or coil-carrying rotary member of a generator comprises a stack of notched magnetically permeable plates held between a pair of flanges, one rigid with the shaft of the machine and the other held elastically thereon. Each of the flanges is provided with an annular array of angularly equispaced hollow lugs which alternate in length between long and short and extend into the notches of the stacked plates. The long lugs or bosses of one flange lie opposite the short bosses of another and the aligned bosses in the notches of the stack receive the conductors of the rotor windings.