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BELL SYSTEM TECHNICAL JOURNAL 



able of doing in a few minutes the work ordinarily requiring a large 

 gang of men, many times as long to complete. 



An active period of development and experimental field work soon 

 followed the advent of this labor-saving device which has resulted in 

 making available a light type of high grade steel tube derrick. 



Figs. 1 and 2 show a pole derrick of the latest type mounted on a 

 2}^ ton truck. Fig. 1 illustrates the method of erecting a pole where 

 the truck can be maneuvered into a position in close proximity to the 

 proposed location of the pole. Fig. 2, on the other hand, shows the 

 possibility of handling a pole at a considerable distance from the 

 location of the truck, which for any reason may be more practicable 

 or desirable. 



These illustrations show the derrick in each of the two possible 

 operating positions; in the first instance supported entirely upon the 



Fig. 1 — Erecting Pole, all Derrick Members Mounted on Truck 



truck, and in the second, supported from the ground by one of the 

 three pipe members. The derricks of this type are constructed of 

 high grade steel tubing having a strength at the yield point of ap- 

 proximately 70,000 pounds per square inch. 



