SOLDERLESS WRAPPED CONNECTIONS PART I 



539 



arm A^ , which decreases a slight amount as the wrapping tension AF 

 increases (see Fig. 15), is equal to 2ah/{a + 6)*. Therefore, Ae = 2 

 (0.042'' X 0.0242'0/(0.042'' + 0.0242'0 = 0.0307 in. Thus the tension 

 in the wire WF = T/Ae = 37.2/0.0307 = 1210 grams. Using the re- 

 covery angle of the terminal as a measure of force, the tension in the 

 wire can now be plotted in terms of angular twist. This is shown in 

 Fig. 16. It should be noted that the tension in the wire WF (wrapped 



25 30 35 40 45 



ANGLE OF TWIST IN DEGREES 



Fig. 16 — Forces in terms of angular twist. 



force) is not directly proportional to the wrapping tension AF (appUed 

 force). The reason for this is that at low applied wrapping tension the 

 bending of the wire around the corner of the terminal produces an addi- 

 tional increment of tension. For example at an angle of 15° the wrapped 

 tension WF is nearly twice as high as the applied tension AF. The 

 wrapped tension WF and the applied tension AF are about equal when 

 the angle of twist is 33°. At higher values of applied tension, the wrapped 

 tension increases at a much lower rate. This is caused by the terminal 

 taking a set. (See Fig. 13.) At 1300 grams of applied tension, which is 

 the reconamended wrapping tension for No. 24 copper wire, the wrapped 

 tension is 1210 grams. 



See Appendix I. 



