. The Bell System technical journal . Fig. 1—Erecting Pole, all Derrick Members Mounted on Truck truck, and in the second, supported from the ground by one of thethree pipe members. The derricks of this type are constructed ofhigh grade steel tubing having a strength at the yield point of ap-proximately 70,000 pounds per square inch. USE OF LABOR-SAVING APPARATUS 55 In order that country-wide conditions may be satisfactorily met,the present type of derrick has been made available in two generaltypes which are known as the middle and corner types for use,as the names imply, from the rear middle
. The Bell System technical journal . Fig. 1—Erecting Pole, all Derrick Members Mounted on Truck truck, and in the second, supported from the ground by one of thethree pipe members. The derricks of this type are constructed ofhigh grade steel tubing having a strength at the yield point of ap-proximately 70,000 pounds per square inch. USE OF LABOR-SAVING APPARATUS 55 In order that country-wide conditions may be satisfactorily met,the present type of derrick has been made available in two generaltypes which are known as the middle and corner types for use,as the names imply, from the rear middle or corner of the of these types are further available in light and heavy weights,depending upon the lengths and the kinds of poles, cedar or chestnutor other kinds of similar weights, that are generally used in any par-ticular part of the country. As contrasted with the early type of derrick, the present typesweigh from 370 to 520 pounds, depending upon the size used,. Fig. 2—Erecting Pole at Distance from Truck, One Derrick Member on Ground and are capable of readily and safely handling any load withinthe limits of the winch rope capacity, which leaves a satisfactorymargin when doing practically any work for which the derrick has aplace in telephone construction. Each of the four classes of derricksabove mentioned is designed with a view to making its operation asrapid as is consistent with safety. The chauffeur and one man canremove the derrick members from the carrying racks provided onthe truck, assemble them and erect the derrick ready for work infrom three to four minutes. The disassembling of the derrick re-quires about the same length of time. 56 BELL SYSTEM TECHNICAL JOURNAL Naturally, the greatest economies may be made in the applicationof this apparatus where the poles to be handled constitute a con-secutive line, the holes for which have been dug in advance. How-ever, because of the short time required for assembling and takingdown the
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
