Developments in the Manufacture of Lead-Covered Paper- 

 Insulated Telephone Cable * 



By JOHN R. SHEA 



This paper describes developments in the manufacture of lead covered 

 paper insulated telephone cable completed during the past three years. 

 The introduction describes the manner in which cable is used in the telephone 

 system and briefly outlines the manufacturing processes and equipment as 

 they existed about three years ago. The new developments are then 

 treated in considerable detail, the most outstanding of which are the 

 application of wood pulp insulation direct on the wire instead of spirally 

 wrapping manila rope ribbon paper; new equipment for vacuum drying and 

 storing cable in which a large storage room of unique construction is provided 

 with conditioned air at a relative humidity of .5 per cent at 100° F.; the 

 central melting of large quantities of lead alloy and its distribution through 

 piping systems to a number of lead presses; improved and larger sheathing 

 presses; and precision electrical testing of the finished cable. Most of these 

 improvements are incorporated in the new Baltimore Cable Plant of the 

 Western Electric Company. 



PAPER-INSULATED lead-covered telephone cable constitutes 

 approximately 25 per cent of the Bell System telephone plant. 

 The cost of new telephone cable each year, including installation, 

 averages $100,000,000. Developments in the process and equip- 

 ment for its manufacture are numerous and have been a large con- 

 tributing factor in the establishment of a high standard of service in 

 the long-distance communication field. The problems involved in 

 manufacturing engineering are extremely interesting both from an 

 economic and technical standpoint to the mechanical and the electrical 

 engineer, the physicist, and the chemist, and the illustrations which 

 follow contain fundamental engineering principles of use in many lines 

 of industry. 



Before proceeding directly with these problems, a brief outline of 

 how cable and its associated apparatus function in the long distance 

 communication field will be of value. After presenting this broad 

 picture, the bulk of the paper will be devoted to an engineering dis- 

 cussion of developments in the process and equipment for manu- 

 facturing cable as illustrated by recent improvements introduced in the 

 new cable plant of the Western Electric Company at Baltimore and at 

 the Kearny, New Jersey, and Chicago plants. 



* Presented at A. S. M. E. meeting, Cleveland, Ohio, April 13-17, 1931. Published 

 in abridged form in Mech. Engg., April. 1931. 



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