. The Bell System technical journal . tioned previously isto form a nonmagnetic surface between the magnetic coating and thecast-iron core since, if the coating were applied directly to a ferro-mag-netic material, its effectiveness would be greatly reduced by the shuntingeffect of the base material. The brass sleeve also serves to facilitate plat-ing the drum, since brass, unlike cast-iron, is amenable to the electro-plating process. Read-Write Heads One of the read-write heads is shown in Fig. 9. The magnetic structuredconsists of three rectangular bars of laminated material, arranged in thei
. The Bell System technical journal . tioned previously isto form a nonmagnetic surface between the magnetic coating and thecast-iron core since, if the coating were applied directly to a ferro-mag-netic material, its effectiveness would be greatly reduced by the shuntingeffect of the base material. The brass sleeve also serves to facilitate plat-ing the drum, since brass, unlike cast-iron, is amenable to the electro-plating process. Read-Write Heads One of the read-write heads is shown in Fig. 9. The magnetic structuredconsists of three rectangular bars of laminated material, arranged in theijform of a triangle (as schematically represented in Fig. 2). Two legs of jthis triangle carry single-layer coils which are series-connected. These;two legs also serve as pole-tips, being pointed at the end and separated (by an air gap. The third leg sorx-es to complete the magnetic circuit and, fin assembly, is butted tightly against the other members by means of a-,Icafspring. MAGNETIC DRUM TRANSLATOR FOR TOLL SWITCHING OFFICES 731. Fig. 9 — Magnetic head and mounting bracket showing means of adjustment. I The magnetic structure is assembled on a nickel-silver plate to whichhave been soldered two copper shoes which serve to locate the pole piecesand shield the pole-tips, thereby focusing the recording flux to some de-gree. After adjustment of the pole-tips, the assembly is clamped in aI sandwich by means of a second, smaller nickel-silver plate. As is evidenti from the illustration, this magnetic assembly is in turn assembled to amounting bracket which contains facilities for precisely adjusting theclearance between pole-tips and drum surface. The pole-tips of the head are wide and the tracks are on , leaving a nominal value of between tracks to allow formisalignment of heads and for flux-spreading. Heads which are physi-i cally adjacent in each of the four corner stacks are mounted on , but the stacks are offset with respect to one another
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
