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BELL SYSTEM TECHNICAL JOURNAL 



would be most favorable to the making of the smallest size of wire and to 

 use the average torque value from an empty to a full reel for the different 

 tension requirements for the other curves. Therefore the composite curves 

 as shown by diagram, Fig. 8, show the result of this compromise. 



The curves showing the results of the test run of the takeup motors are 

 shown by Fig. 9, which demonstrates how closely the motor manufacturer 

 met the requirements of Fig. 8, which are superimposed for reference. 



The minimum of slip between the wire and capstans has been incorporated 



TAKE-UP SHAFT SPEED 



Fig. 7 — Power requirements for torque motor for takeup of wire sizes No. 19 A.W.G. 

 and smaller to secure uniform tension 



into the design to secure the greatest economy of power. Each reduction of 

 one size A.W.G. increases the length by 26%; and a ratio of 23% between 

 each capstan step has been found most economical. To further reduce 

 power required, ratios of 25% have been used, but because of the uneven 

 wear of diamonds this ratio is disturbed and excessive breaks occur at the 

 location where the die has worn the fastest. With the ratio of 25%, dies 

 must be kept more evenly matched for reduction in area, and the expense 

 of rematching dies, and the loss of production during the period of re- 



