128 BULLETIN" "yil, U. S. DEPARTMENT OF AGRICTJLTTJEE. 



Mcdn cable supports. — In the case of the tree-rigged system trees 

 support the main cable (fig. 36). The head spar, only one of which 

 is required to log an entire setting, may be a tree that, as a result 

 of accident or design, is located at the proper place; or it may be 

 a pole erected there. The head spar is from 100 to 150 feet in height 

 and about 30 inches in diameter at the top. If a tree is used, and 

 such is usuallj^ the case, the top is cut off to protect the workers and 

 the machine from falling limbs. The head spar is braced with from 

 six to nine guys attached to the top of the spar or at both the top 

 and middle. The tail trees are selected before felling begins and are 

 left standing, although occasionally a top is cut off to avoid trouble. 

 The tail trees are also guj^ed. 



The distance between the main cable supports (fig. 41) ordinarily 

 ranges from 800 to 1,400 feet, which means that an area of from 40 

 to 100 acres can be logged at one setting. Logs can be yarded as far 

 as 200 feet behind the tail tree. On steep mountain sides, the skidder 



Fig. 41. — Location of roads, Lidgerwood overhead system. 



may be rigged to yard logs 2,000 feet or more; in rare cases, up to 

 3,000 feet. 



It is necessary to use a new tail tree with every run. The distance 

 between the runs depends on several factors, such as the character 

 of the ground, size of timber, density of stand, location of suitable 

 tail trees, etc. The tail trees are usually from 150 to 250 feet apart. 

 The closer they are together, the easier it is for the tong men, and 

 the more work it means for the rigging crew. The best results with 

 this system are ordinarily obtained when the skidder is hauling 

 about 1,000 feet and the tail trees are about 150 feet apart. 



Operation. — In operation, the return line draws the carriage out 

 along the main cable. When the carriage reaches the place where 

 the logs are to be picked up, the return line drum is thrown out of 

 gear and the foot brake is applied, holding the carriage stationary. 

 The tongs or chokers are then lowered to the ground by drawing in 

 the slack-pulling line. After the slack is pulled, the tongs or chokers 

 are carried out by the tong man, to the log or logs to be hauled and 

 attached. The skidding rope is then drawn in, with the return line 



