94 BELL SYSTEM TECHNICAL JOURNAL 



municated by a system of rods to the clutch so that it tends to speed up or 

 reduce the speed of the take-up spool. With the long coiled spring wound 

 to a definite tension a predetermined pull on the wire can be maintained. 

 Two spools are driven simultaneously side by side through suitable gears. 

 Each spool, however, is held on a separate arbor which can be pulled out of 

 mesh with the driving gear so that the take-up spool can be stopped and 

 removed. When it is desirable to do this the wire being taken up is simply 

 switched over to the other spool and when a few turns have been taken up 

 the wire between the spools is cut so that the first spool can be removed 

 from the machine (Fig. 8). Sixty spools are run at one time at an average 

 speed of 140 feet per minute or a total wire footage of 8400 feet per minute 

 of running time. Improved beating, better pulp, better cleaning and im- 

 proved drying and polishing as well as better trained employees in the last 

 few years have greatly improved the product over the original and simplified 

 the control of the process. 



Types of Wire Insulated 



As mentioned in the first few paragraphs the trend in telephone cable 

 construction has been toward finer and finer wire. The insulating equip- 

 ment and process described are particularly well adapted to apply coatings 

 of pulp from six to ten mils in thickness to gauges of wire between 19 and 

 30-gauge. Changes in the mechanical equipment would be necessary for 

 handling wire finer than 30-gauge or wire heavier than 19-gauge. As little 

 demand for these gauges exists in exchange area telephone circuits, no 

 attempt has been made to adapt the machine to these sizes. However, use 

 of the process can be extended quite widely both in the type of materials 

 used for insulating and kind of wire covered, if demand for such extension 

 exists. So far the development of this insulation process has made it 

 possible to produce wires with insulations so thin that 1515-pair cables of 

 24-gauge wire and 2121-pair cables of 26-gauge wire are now commercially 

 available to the telephone companies with no increase in external diameter 

 of the lead sheath now used. More effective use of existing underground 

 ducts can therefore be made, eliminating possible large expenditures by the 

 telephone companies for such facilities. 



