138 BULLETIN 711, TJ. 
S. DEPARTMENT OE AGRICULTURE. 
The carriage has two sheaves, being light, simple, and strongly 
constructed. On the bottom is a large hook, to which the chokers are 
attached, and a small hook at each end, the haul-in line being attached 
to one, the haul-back line to the other. The carriage (fig. 45), with 
16 by 3 inch manganese-steel sheaves, costs about $120. 
The blocks are much the same as those used in high-lead yarding. 
The price of overhead blocks is given under " Loading." The fol- 
lowing gives the number, types, and selling prices of blocks used 
with this system at one camp : 
Net selling price. 
Type and size: 
1 14-inch tree jack (fig. 46) $180 
3 large moving blocks 150 
2 yarding blocks . 50 
2 18-inch trip or haul-back blocks 50 
6 14-mch trip or haul-back blocks 105 
2 tree shoes (fig. 47) 1 100 
45. — Double-sheave over 
head carriage. 
Fig. 46. — Tree jack. 
Fig. 47.— Tree shoe. 
Output. — The output with this system ranges from 50,000 to 100,000 
feet per day. At one camp where the logs were moved 1,500 feet 
down a steep slope the output averaged about 60,000 feet per day, 
the logs averaging about 800 feet in volume. In the same camp 
the output gveraged from 85,000 to 100,000 feet per day on practically 
level ground, when the hauling distance did not exceed 1,000 feet. At 
another camp, where the logs were moved 2.000 feet down a steep 
mountain side, the output averaged about 50,000 feet per day, the logs 
averaging about 900 feet in volume. At still another camp, where 
the logs were, moved about 1,600 feet down a steep slope, the country 
being badly broken up, the output ranged from 60.000 to 80,000 feet 
per day. In this latter case the timber was large, the logs averaging 
2,000 feet in volume, and some of them containing 6.000 feet. 
1 A tree shoe is used to support the overhead cable at the tail tree. Since the tighten- 
ing is generally done at the head tree, the outer end of this cable is stationary, making 
a hardwood shoe instead of sheaves practical. 
