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BELL SYSTEM TECHNICAL JOURNAL 



20g. Then, from Equation 1.3.4, the approximate displacement that will 

 be required is 



, 2 X 60 ^ . , 



dm = — r^r — = 6 mched 



(1.7.1) 



The actual maximum displacement in a tension spring package will prove 

 to be somewhat more than 6 inches, but the preliminary calculation shows 

 the displacement to be large enough to warrant the use of this type of 

 cushioning. 



H G 



Q B 



Fig. 1.7.1 — Schematic diagram of a tension spring package. 



A schematic diagram of a typical tension spring package is shown in Fig. 

 1.7.1 and a photograph of one design is given in Fig. 1.7.2. The packaged 

 item is suspended on eight identical helical tension springs which diverge 

 to the outer frame. The analysis and design procedures described in this 

 and the following section apply equally well if the springs converge from the 

 packaged item to the outer frame. With a slight modification, indicated 

 in the next section, the procedure also applies if four of the springs (say, 

 BJ, DL, EM, OG in Fig. 1.7.1) are omitted. 



In all cases, however, we shall consider only systems having reflected 

 symmetry about each of three mutually perpendicular planes through the 

 center of gravity of the packaged article. 



