TRACTORS 
209 
in the direction of skidding in case thvy are to be drass^'d on the 
ground, or in the opposite direction if long logs are skidded with 
the front end resting on some form of a log carrier. Dragging 
is rarely practiccHl for distances c^xceeding | or ^ mile. How- 
ever, in the Appalachian and other mountainous regions, a number 
of logs may be coupled together in a "turn" and dragged by trac- 
tors for long distances on skidding roads. 
Log carriers supporting only the front ends of the logs, and 
J'hnln./nii'li l>!/ A. Koroicff. 
Fig. 60. — A 10-Ton Holt Caterpillar Tractor drawing Logs loaded on a 
Caterpillar Bummer. Idaho. 
having a capacity of from 2000 to 4000 boar4 feet are used in 
tractor skidding to suit different conditions and seasons of the 
year. Various types of bummers, dollies, trailers, go-devils, 
and big wheels, which differ from those used in animal logging 
chiefly in their stronger construction and larger capacity, also 
are used. Bummers of the crawler type are preferred when 
hauling on soft or swampy bottom, or when hauling very heavy 
loads on bad roads. They usually are of all-steel construction 
and have two free-running crawler-typ.e members of comparatively 
simple construction, and a single or double bunk. The usual 
