MAGNETIC DRUM TRANSLATOR FOR TOLL SWITCHING OFFICES 729 



Fig. 8 — Magnetic diiun unit pnrllN- uncovered to show magnetic iieads and 

 wiring terminals. 



dirt iiiid foreign material from the magnetic drum surface and the bear- 

 ings. The Ke-hp motor dri\'es the drum through a spring-diaphragm 

 coupling. 



The drum is comprised of a stress-reheved iron casting of high dimen- 



-^ional stabiHty, a press-fitted steel shaft, and a ^^ie" thick brass outer 



, sliell which carries the magnetic recording medium. Since both drum and 



