A New General Purpose Relay for Telephone Switching Systems

A New General Purpose Relay for Telephone Switching Systems By ARTHUR C. K E L L E R (Manuscript received July 14, 1952) This paper describes a new general purpose electromagnetic relay for use in telephone switching syste?ns. It is a wire spring relay known as the AF type relay and, with variations which provide slow release or marginal characteristics, it is known as the AG and A J relay, respectively. Fig. 1 shows a typical AF type relay, Fig. 2 shows all of the parts of the relay and Fig. 3 is a drawing showing the relay assembly. 1. BACKGROUND T h e general purpose relay is one of t h e most i m p o r t a n t c o m p o n e n t s of telephone switching systems. 1 These relays c o n s t i t u t e t h e m o s t repetitive building block in switching e q u i p m e n t . Since several million are produced annually, low m a n u f a c t u r i n g cost is extremely desirable. Also of prime importance are low operating and m a i n t e n a n c e costs. General purpose relays are, therefore, u n d e r c o n s t a n t observation a n d s t u d y by the telephone operating companies as the users, by the W e s t e r n Electric C o m p a n y as the m a n u f a c t u r e r , a n d by Bell Telephone Laboratories as t h e designer. T h e AF wire spring relay a n d its variations are t h e result of such studies. A general purpose relay for telephone switching systems m u s t meet a large n u m b e r of diverse requirements. It m u s t be capable of being assembled with a n y one of a v a r i e t y of m a g n e t coils h a v i n g a wide range 1 S.