SOLDERLESS WRAPPED CONNECTIONS PART I 553 



EVALUATION 



The solderless wrapped connection has been compared with other 

 pressure connections. (See Fig. 35.) However, when compared with a 

 soldered connection its advantages are as follows: 



1. A substantial reduction in wiring defects in manufacture and in 

 service because of: — 



a. Greater uniformity obtained with a calibrated tool. 



b. Less breakage of wires due to handling and vibration. 



c. No solder splashes. 



d. No clippings. 



e. No cold joints. 



f. No rosin joints. 



2. Less expensive connection. 



3. More compact connection. 



4. More clearance between current carrying parts. 



5. Easy to disconnect. 



6. Saving of tin — a critical material. 



7. No contact contamination from soldering fumes. 



8. No damage to heat sensitive materials in circuit components. 



9. No hazard from hot soldering iron. 



SUMMARY 



A good pressure connection depends on the amount of elastic energy 

 which can be stored in the mutually stressed members, namely the wire 

 and terminal. If the ratio of elastic energy to the size of the connecting 

 members is favorable, and the contacting areas are sufficiently large, 

 then the connection can be termed good. The solderless wrapped con- 

 nection when properly proportioned not only meets these requirements, 

 but is uniform in quality and low in cost. 



Appendix I 



EFFECTIVE MOMENT ARM FOR TORSION OF RECTANGULAR TERMINAL 



In this appendix the relationship between the wrapped tension in the 

 wire and the twist of the terminal will be analyzed. The structure of the 

 solderless wrapped connection is equivalent to a terminal having springs 

 attached between its edges as shown in Fig. 36. The springs are arranged 

 in such a way as to form a helix of pitch p. Now let: 



Su = torsional stiffness of a unit length terminal 

 WF = wrapped tension 



