TELEPHONE APPARATUS SPRINGS 



Nickel Silver 



261 



Phosphor Bronze 



0.040 in. and 



thicker. . . . 



Below 0.040 



0.040 in. and 



thicker. . . . 



Below 0.040 



0.040 in. and 



thicker. . . . 



Below 0.040 



Extra hard 

 Extra hard 

 Spring 

 Spring 

 Extra spring 

 Extra spring 



55,000 



ISXlO'' 



Note: The proportional limit and modulus figures are representative. They are 

 only slightly changed by cold work. 



OPERATIONS 



Fig. 2 — Fiber stress vs. fatigue — brass sheet — 24 gage — 4 Nos. hard: 

 A, average of three specimens taken from test without failure. 



