86 



BULLETIN 711, U. S. DEPAETMENT OF AGEICULTURE. 

 Trip-line head hloeks {Fig. 22). 



No. 



Sheave. 



Pin. 



Hub. 



Weight. Net price. 



1 

 2 

 3 



Inches. 

 14 by U 

 18byl| 

 24 by 2 



Inches. 

 24 

 2i 

 3 



Inches. 

 3 

 4 

 5 



Pounds. 



95 1 $17. 60 

 140 26.00 

 235 ; 44.00 



1 



Extra parts. 



Items. 



Net price. 



No. 1. No. 2. No. 3 



Forged-steel shackle 1 $1.20 



- 7.20 



2.00 



.60 



.40 



1.60 



7.60 



Pair steel block sides . 



Casehardened steel pin 



Oil cup and nut with lock washer 



Half nut with lock washer 



Bronze bushing 



Manganese-steel sheave, bronze bushed. 



$1.60 



9.60 



2.60 



.60 



.45 



2.00 



12.20 



$2.80 



18.80 



3.20 



1.40 



.60 



3.60 



20.00 



1 No. 3 has tool-steel forged shackle. 



Table 11 gives the fixed investment in ground yarding blocks for 

 one yarding engine. To allow for a proper range, the total cost and 

 weight, including blocks of different sizes, is shown in three cases. 

 The aim is to include a liberal amount of such equipment, taking into 

 account the fact that the number of blocks needed for different yard- 

 ing chances varies and that some blocks are undergoing repairs at 

 times. This table can be easily modified to take care of a given set 

 of conditions. 



Table 11. — Fixed investment in blocks for one yarding engine. 



Items. 



Butt chain blocks. . . 



Moving blocks 



Yarding blocks 



Head trip block 



Comer or side block. 



Side blocks 



Extra parts 



Total. 



Case 1. 



24 by 8 

 16 by 3 

 12 by 2i 

 24 by 2 

 14 by U 

 12 by li 



1,640 

 540 

 290 

 235 

 96 

 440 

 400 



3,640 



$256. 00 

 99.00 

 63.60 

 44.00 

 17.60 

 96.00 

 100. 00 



666. 00 



Case 2. 



20 by 7 

 14 by 3 

 10 by 2i 

 18 by l| 

 14 by H 

 12byli 





1,300 

 460 

 220 

 140 

 95 

 440 

 300 



2,955 



$204.00 

 90.00 

 45.60 

 26.00 

 17.60 

 96. 00 

 75.00 



Cases. 



16 by 7 

 14 by 3 

 10 by 2i 

 14 by li 

 14 by li 

 12 by li 



554. 00 



950 

 460 

 220 

 95 

 95 

 440 

 250 



Prices are those of March, 1916. 



Yarding rollers. — Figure 28 shows a yarding or stump roller. 

 The use of such rollers in connection with ground yarding is dis- 

 cussed on page 72. The method is also shown in figure 15, They 

 weigh from 210 to 325 pounds and cost from $45 to $60. 



Ground yarding lineft. — Ground yarding lines are all made of wire 

 rope, without which modern methods of logging could not have 

 developed. Wire rope consists of a group of strands laid sym- 



