84 



BULLETIISr 711, V. S. DEPARTMENT OF AGRICULTURE. 



blocks, SO thiit there is a large assortment for operators to select 

 from. 



Blocks of as large size as possible should be used. Wire-rope man- 

 ufacturers recommend blocks with much larger sheaves than are 

 practical in the woods. For 1-inch lines sheaves should not be less 

 than 12 inches in diameter; and for 1^ to 1^ inch lines, from 14 to 

 18 inches. The standardization committee of the Pacific Logging- 

 Congress in 1913 recommended that blocks having sheaves of the 

 following sizes be adopted : 



Trip-line Wocks: 



9 by li by lis inches, hub length 3 inches, grooved for a f-inch line. 

 12 by li by lil inches, hub length 3 inches, grooved for a |-inch line. 

 14 by 1^ by 2i's inches, hub length 3 inches, grooved for a |-inch line. 

 18 by l| by 2/5 inches, hub length 4 inches, grooved for a |-inch line. 

 24 by 2 by Si^ inches, hub length 5 inches, grooved for a |-inch line. 



Yarding blocks: 



10 by 2 by 2^ inches, hub length 3 inches, grooved for a l:i-inch line. 



12 by 21 by 211 inches, hub length 3^ inches, grooved for a li-inch line. 

 Butt-chain blocks: 



16 by 8 by 3iV inches, hub length 8 inches, if grooved for a li-inch line. 

 20 by 8 by S/s inches, hub length 8 inches, if grooved for a l^-inch line. 

 24 by 8 by 3iV inches, hub length 8 inches, if grooved for a Iz-inch line. 



The cost of blocks varies because of differences in the type, size, 

 •and make and because different material is used in their construction. 

 The following tabulations give the type, size, and weight of blocks 

 that are more or less standard, also the selling prices f. o. b. Port- 

 land in March, 1916. The material used in the construction of these 

 blocks is indicated in the list of extra parts. 



Butt-cJiain lead blocks {Fig. 25). 





No. 



Sheave. 



Shaft. 



Bearing. 



AVeight. 



Net price. 









1 

 2 

 3 



Inches. 

 24 by 8 

 20 by 7 

 16 by 7 



Indies. 



f 



Inches. 

 10 

 10 

 10 



Pounds. 

 820 

 650 

 475 



8128.00 

 102.00 

 72.00 











Extra parts. 















Itei 



ns. 





Net piice. 





No. 1. 



No. 2. 



No. 3. 



Tool-steel si 

 Pair steel b] 

 Casehardene 



lackle 









$18.80 



44.00 



6.00 



1.40 



.60 



7.60 



50.00 



«17. 20 



34.00 



6.00 



1.40 



.60 



7.60 



fl5.25 



ock sides 









24.00 



d steel Renter shaft 







6.00 



on cup and nut with lock wa-sher 



1.40 



iialf nut with lock washer. 









.60 



Bronze bus! 

 Manganese-s 



in? 









7.60 



teel sheave, bronze buhhcd 







38 



00 



28.00 



