88 



BULLETIN 711, U. S. DEPARTMENT OF AGEICULTUEE. 



made in this manner, and it has become standard for general work. 

 In the latter, the wires in the strand and the strands in the ropes 

 are twisted in the same direction. 



Wire ropes are made almost exclusively from iron or steel, and 

 the materials used may be further grouped into three main divi- 

 sions, viz, iron, crucible cast steel, and plow steel. The wire rope 

 used for ^''arding lines is for the most part made from plow steel 

 and special plow steel. These two classes of rope, besides being 

 used for main, trip, and straw lines, are used for chokers and over- 

 head yarding lines, the special plow steel being especially adapted 

 for overhead work. For lines other than chokers a 6 by 19 con- 

 struction with a hemp core is used. A small percentage of operators 

 make their main j^arding lines from rope that has a steel core. 



The diameter and length of lines is discussed under the heading 

 " Wire rope cost." 



The selling price of wire rope, besides varying with the grade and 

 type of construction, fluctuates with economic conditions. The list 

 prices of manufacturers for the same grade and construction are 

 the same. On March 8, 1916, the discount quoted b}'^ one wire- 

 rope agent was 37^ per cent off the list prices. About two years 

 ago the discount was about 60 per cent. Under normal conditions 

 the discount is about 50 per cent. 



The following tables give the net prices on wire rope of the 

 grade and type of construction ordinarily used in logging opera- 

 .tions. The prices are based on a discount of 50 per cent off the list. 

 The strengths given are standard, being those adopted hj the manu- 

 facturers on Mav 1. 1910. 



Table 12. — Standard plow steel hoisting rope. 

 [6 strands, 19 wires to the strand, 1 hemp core.] 



Net price 



] diameter 



Approxi- 

 mate 

 weight 

 per foot in 

 pounds. 



Approxi- 

 mate 

 strength 



Proper 

 working 

 load in 



per foot. 



in inches. 



in tons of 



2,000 



pounds. 



tons of 



2,000 



pounds. 



$0.06 



i 



0.10 



2.65 



0.53 



. 06025 



A 



.15 



3.8 



.76 



.0625 



t 



.22 



5.75 



1.15 



.065 



17 



.30 



8 



1.6 



.07 



i 



.39 



10 



2 



.08 





.50 



12.3 



2.4 



.095 



1 



.62 



15. 5 



3.1 



.13 



1 



.89 



23 



4.6 



.17 



1 



1.20 



29 



5.8 



.215 





1.58 



38 



7.6 



.27 



li 



2 



47 



9.4 



.325 





2.45 



58 



12 



.395 



l| 



3 



72 



14 



.465 



14 



3.55 



82 



16 



.54 



}t 



4.15 



94 



19 



.65 



4.85 



112 



22 



.73 



li 



5.55 



127 



25 



.79 



2 



6.3 



140 



28 



Note.— The net prices given are based on a discount of 50 per cent off the list prices. Add 10 per cent 

 to the list prices for wire center. 



