Twentieth century hand-book for steam engineers and electricians with questions and answers; a practical non-technical treatise .. (1913)
Swingle, Calvin Franklin, 1846- [from old catalog] · Chicago, F. J. Drake & company · leaf 1075
called Drum cores when the central holeis just large enough for the shaft and the insulation aroundit (Fig. 439) ; and are named Ring cores when the inter-nal diameter of the ring is much larger than the shaft.(Fig. 441.) The armature in Fig. 442 has a ring core^, butthe end plates being in… … Fig. 441simple gramme ring winding parted on. The rust, varnish and paper are all insulatorsand when the punchings are assembled in a qotq, preventEddy currents from flowing from one end of the armatureto the other and heating it. These cores are sometimes smooth, but more frequentlyare slotted…
