84 
BULLETIN 711, U. S. DEPARTMENT OF AGRICULTURE. 
blocks, so that 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 lj to 1J 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 blocks: 
9 by li by Iff inches, hub length 3 inches, grooved for a f-inch line. 
12 by 1£ by lit inches, hub length 3 inches, grooved for a f-inch line. 
14 by 1L by 2iV inches, hub length 3 inches, grooved for a f-inch line. 
18 by li by 2t 7 b- inches, hub length 4 inches, grooved for a f-inch line. 
24 by 2 by 3ik inches, hub length 5 inches, grooved for a f-inch line. 
Yarding blocks: 
10 by 2 by 1\ inches, hub length 3 inches, grooved for a 11-inch line. 
12 by 2i by 2 if inches, hub length 3 J inches, grooved for a li-inch line. 
Butt-chain blocks: 
16 by 8 by 3t 7 6 inches, hub length 8 inches, if grooved for a l^-inch line. 
20 by 8 by 3t 7 6 inches, hub length 8 inches, if grooved for a l|-inch line. 
24 by 8 by 3i 7 6 inches, hub length 8 inches, if grooved for a 11-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-chain lead blocks (Fig. 25). 
No. 
Sheave. 
Shaft. 
Bearing. 
Weight. 
Net price. 
1 
2 
3 
Inches. 
24 by 8 
20 by 7 
16 by 7 
Inches. 
f 
Inches. 
10 
10 
10 
Pounds. 
820 
650 
475 
$128. 00 
102.00 
72.00 
Extra parts. 
Items. 
Net price. 
No. 1. 
No. 2. 
No. 3. 
Tool-steel shackle 
$18. 80 
44.00 
6.00 
1.40 
.60 
7.60 
50.00 
$17. 20 1 
34.00 i 
6.00 
1.40 ! 
.60 I 
7.60 I 
38.00 ! 
§15. 25 
24.00 
Casehardened steel center shaft 
6.00 
Oil cup and nut with lock washer 
1.40 
fialf nut with lock washer 
.60 
Bronze bushing 
7.60 
Manganese-steel sheave, bronze bushed ...... 
28.00 
