Design features of Bell System wire spring relays

THE Bell Telephone System wire spring relays have become the basic circuit components of telephone switching systems developed during the past few years. These relays are provided in many varieties to meet circuit needs. They are similar in operation and construction and have been described to a large extent in earlier publications.1,2 It is the purpose of this paper to highlight some of the design features which permit automatic control, during manufacture, of important operating characteristics. This subject has not been covered in the earlier articles and is of considerable importance to low-cost manufacture and proper operation of these relays.