258 
LOGGING 
unloading points. The snubbing line passed through a 2-sheave 
trolley and had a ball near the free end which engaged a catch 
in the trolley and served to hold the load in position, and to trip 
it at the lower end. Power for returning the trolley to the head 
of the tram was furnished by a drum on a yarding engine at the 
head of the slope. A cable was fastened near the ends of a log 
that was to be transported. A hook on the end of the snubbing 
line was then caught in a ring midway between the ends of the 
cable and the log hoisted into the air. When the ball on the 
Adapted from The Timberman. 
Fig. 82. — A Single-cable Aerial Tramway in use in the Pacific Coast Forests 
for lowering Logs on Steep Slopes. 
snubbing line struck the catch in the trolley, the latter was freed 
from the stop at the head tree and with its load passed down the 
main cable by gravity, the speed being controlled by the yarding 
engine. On reaching the lower end of the cable the trolley was 
automatically tripped and the log lowered to a skidway along a 
railroad. Poles 100 feet long were handled with ease. The 
average time required to traverse the distance from the head to 
the foot of the tramway was one and one-quarter minutes. 
One of the early successful attempts made to move logs for 
long distances by an aerial tramway system was undertaken in 
Idaho in 1912 when a line 1| miles in length was installed 
to bring timber out of a region in which the cost of railroad build- 
ing was prohibitive. It was later modified and used to bring 
out timber from other portions of the forest. This system was 
not used, however, when logging railroad construction costs were 
within the limits which the company considered justifiable. 
