A New Multicoiitact Relay for Telephone 

 Switching Systems 



By I. S. RAFUSE 



(Manuscript received April 8, 195-1) 



The trend in new telephone switching systems toward faster operation, 

 longer life and lower cost, indicates a need for faster and more capable control 

 circuits. This paper describes a new high speed wire spring ynulticontact 

 relay designed primarily for these applications. The basic unit contains 30 

 make-contact pairs. Two variations of the new design provide relays of 

 60-contact capacity. They are mechanically and electrically interchangeable 

 with all crossbar system muUicontact relays. 



INTRODUCTION 



In a modern dial telephone central office, many thousands of mo- 

 mentary intraoffice control connections are made daily between the 

 various parts of the switching equipment. For example, in the No. 5 

 crossbar S3^stem, seven major types of connectors are used to associate 

 markers^ with other common control circuits, and with the switching 

 frames, for brief intervals, to assist in setting up the talking connection. 

 Connectors are required to simultaneously close a large number of circuit 

 paths, as many as 240 in the trunk link connector. The earlier flat spring 

 type multicoiitact relays* used for this purpose provide large blocks of 

 contacts per relay and provide an economical means for common or 

 multiple wiring. 



The trend in new improved switching systems toward longer life, 

 faster operation, lower cost and reduced maintenance, indicates a need 

 for faster and more rehable connector circuits. This paper describes 

 a new multicontact relay, designed primarily for these apphcations. 

 It is a wire spring relay incorporating the improved manufa('turing 

 processes and many of the design features of the new general purpose 

 wire spring relay.* The basic unit. Fig. 1, for use in new equipments, is a 

 high speed 30-contact pair relay, with wiring terminals arranged for 

 horizontal multiple connections. 



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