POWER SKIDDING 221 
extending from the head spar to each tail tree. This work is 
done a short time in advance of skidding. One man can cut the 
runs when the brush is of medium size. 
Two main cables are used on spans less than 2500 feet. This 
saves the cable since its ends are reversed at each set up, but 
when the spans may vary several hundred feet in length, the 
difficulty of taking care of the surplus cal)le on the shorter hauls 
is a drawback. While one main cable is in use, the rigging crew, 
three men, is at work preparing the new tail tree and placing the 
extra main cable in position on the next run. When the tim})er 
available to one run is skidded, the main cable is dropped to the 
ground and disconnected from the main cable extension; the 
trolley is placed on the new cable, which is then connected 
to the cable extension, and the whole drawn taut for operation. 
It requires from 15 to 30 minutes to make this change. The V 
rigging crew then proceeds to transfer the extra main cable to 
the next run. A block is placed on the new tail tree and a f- 
inch cable is dragged from the engine out over the new run, either 
by hand or by a horse. It is then passed through the block 
on the new tail tree, and finally through a block on the tail tree 
just abandoned. The end of the small cable is attached to the 
main cable and by winding the former on a drum of the engine, 
the main cable is dragged around into the new run, having re- 
versed ends. It is then made ready for use by attaching it to 
the tail tree. 
A different procedure is followed in mountainous regions in 
which the length of span may vary greatly. One main cable 
only is used and this is carried on a reel drum on the skidder. 
This drum is actuated by a special compound-geared tensioning 
engine having two speeds, high for pulling in the main cable 
when runs are changed and low for tightening and tensioning 
the main cable. The drum capacity on the longest range 
machines is 5200 feet of 1| main cable, when a relay system 
or a support-passing trolley is used. The relay method was 
introduced about ten years ago in the Appalachian region 
to log hollows and other places which were not accessible with 
single spans and to reach which would require a prohibitive cost 
of railroad construction. An intermediate tree spar was selected 
on the ridge top that was to be crossed, or at some convenient 
point in the cove that was to be logged.^ The 'main cable and 
1 See Fig. 68. 
