124 BULLETIN 711, U. S. DEPARTMENT OF AGRICULTURE. 



a main cable extension (fig. 38) between the spar trees near the head 

 spar by means of a block and fall tackle, the main cable being tight- 

 ened with the aid of the engine ; or the main cable may lead through 



Fig. 36. — Location of equipment and improvements, Lidgerwood overliead system. 



a jack on the head spar (fig. 39) and then down to a stump, where 

 it is connected. The latter is generally used in this region. The 

 method of tightening is the same in both cases. The steel-spar type 

 is provided with a steel head spar built upon the skidding car and 



carried with it. This steel spar car- 

 ries all the head blocks and rigging, 

 with all the lines reeved and in place. 

 A slack-pulling skidding or yard- 

 ing carriage travels on the cable 

 (fig. 40), being moved toward the 

 head spar by the skidding or haul- 

 ing line and toward the tail tree by 

 the return or trip line. This car- 

 riage also carries the slack-pulling 

 line, which enables the engine to 

 give out the length of skidding line 

 necessary to reach the logs lying to 

 one side or the other of the overhead 

 cable. Lines other than the main 

 standing cable lead from their re- 

 spective drums on the skidding en- 

 gine through blocks on the head 

 spar, or both the head spar and tail 

 tree, and thence through the skid- 

 ding carriage to their respective 

 positions. In operation the over- 

 head cable is stationary. An auxiliary engine is used to load the logs. 

 This system of yarding is a product of the East, having been used 

 for a comparatively long time in the forests of the South anji 



Fig. 37.- 



-Tail tree, Lidgenvood over- 

 liead system. 



