168 
BULLETIN 711, U. S. DEPARTMENT OF AGBICULTIJRE. 
This block is adapted for gin-pole or overhead loading. 
The blocks listed below are adapted for any work where blocks 
are hung in an overhead position and frequent oiling is impossible 
without great loss of time. They are of the auto-lubricating type. 
The sheaves are made of manganese steel. 
Prices of blocks. 
No. 
Sheave. 
Bearing. 
Diame- 
ter pin. 
Weight. 
Net 
price. 
1 
Inches. 
12bv2 
14 by 2 
18bv2i 
24 bv 3" 
24 bv 5 
36 by 3 
Inches. 
3 
3 
4^ 
5" 
7 
8 
Inches. 
2h 
2| 
3 
3i 
3* 
Paunds. 
115 
150 
230 
410 
450 
750 
$27.00 
2 
34.00 
3 
50.00 
4 
5 
81.00 
90.00 
144.00 
TEEE JACK. 
Figure 46 is a cut of one of the types of tree jacks. They are 
designed for extremely heavy duty, such as is found in overhead 
loading and yarding. They are easy on the lines, since the strain 
is equally divided on the three sheaves, the same results being se- 
cured as with an extremely large sheave. The size and net selling 
prices f. o. b. Portland, Tacoma. or Seattle in March, 1916, were as 
follows : 
Tree jacks. 
No. 
Size of 
sheaves. 
Net sell- 
ing price 
with 
manga- 
nese-steel 
sheaves. 
1 
Inches. 
10 by 3 
14 by 3 
16 bv 3 
9 bv 7 
14 by 6i 
16 by 9 
$67. 50 
2 
3 
90.00 
4 
82. 50 
5 
93.75 
6 
114.00 
Spares. 
Item. 
Net price. 
No.l. 
No. 2. 
No. 3. 
No. 4. 
No. 5. 
No. 6. 
S22. 50 
9.75 
5.25 
6.80 
2.65 
$25. 50 
13.50 
6.00 
6. SO 
2.65 
S27. 00 
15.00 
6.00 
7.30 
2.65 
S22.50 
15.00 
5.25 
6.80 
3.40 
S25.50 
18.00 
6.30 
S.00 
3.75 
§27.00 
Bronze bushed manganese-steel sheaves. . . 
24.00 
6. SO 
Set of three pins 
9.00 
5 25 
LOADING LINES. 
The selling price of wire rope is discussed under " Ground yard- 
ing." The length and size of lines used are dealt with under 
" Methods " in this section. 
