A New Multicontact Relay for Telephone Switching Systems

In a modern dial telephone central office, many thousands of momentary intraoffice control connections are made daily between the various parts of the switching equipment. For example, in the No.5 crossbar system, seven major types of connectors 1 are used to associate markers 2 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 multicontact relays3 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 reliable connector circuits. This paper describes a new multicontact relay, designed primarily for these applications. It is a wire spring relay incorporating the improved manufacturing processes and many of the design features of the new general purpose wire spring relay.4 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. 1111