544 THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1953 



Fig, 22 — Air-driven wiring tool. 



end of an insulated wire, hooks or threads it onto the terminal and ap- 

 plies solder. The hooking or threading is important because it is cus- 

 tomary in production to attach several wires at first and then solder. 

 The question now is: If a similar procedure is to be followed with a 

 wrapped connection where the wire must surround the terminal wdth a 

 high pressure, how do we produce that pressure? 



In a screw connection a force is obtained by a high lever ratio. In a 

 crimped connection the force is applied by heavy and powerful com- 

 pression tools. These tools are not suitable for connecting wires to closely 

 spaced terminals such as shown in Fig. 22. To produce high tension in 

 the wire while it is being wrapped onto the terminal, a new method of 

 tensioning had to be devised. 



In the manufacture of helical springs it is customary to anchor the 

 end of the wire in a hole in the arbor and tension the wire with a friction 

 pad. By rotating the arbor a helical spring is produced. For closely 

 spaced terminals this method is not practical as the wire cannot be fed 

 tangentially to the terminal and the terminal cannot be rotated. A new 



