148 
BULLETIN 711, U. S. DEPARTMENT OE AGRICULTURE. 
above the yarding engine. The trip line, which is strung near the 
pole road in such a way that it will not interfere with the operation 
of the main cable, leads through trip blocks located at suitable points 
and then through the tail block, where it is attached to the woods- 
end of the main line. The main cable follows the road and is kept 
in place with blocks or rollers where turns are made. 
From six to eight logs, depending on their size and the character 
of the road, are fastened one behind the 
other by means of grabs or dogs (figs. 53 
and 54), forming turns, which are attached 
to the main cable. The turns are made up 
by a grab man. A chaser follows the logs 
to the landing, often riding in a rigging 
sled hollowed out of a log, which is attached 
to the rear log. He can signal to the road 
engineer at any point along the line by pull- 
ing on a wire which is stretched from the 
road engine. On arrival at the landing the 
chaser aids in placing the logs on the land- 
ing, removes the grabs from the logs, and 
returns with the grabs in the rigging sled 
to the yarding engine. In some cases, especially where the pole road 
is so steep in places that gravity causes the logs to run faster than the 
lines travel, the logs in the turn are not dogged up and pulled to the 
landing. Instead, they are pushed into the landing, a 
hook attached to the main line being made fast to the 
rear log. By this method several turns of logs of the 
ordinary size may be along the road at different points 
at one time. 
It is practically impossible to say how far a road en- 
gine works on the average. Unless conditions are par- 
ticularly favorable one machine will not be able to haul 
farther than 3,000 feet; in many cases less than this. 
At this distance a road engine should generally be able to handle 
the output of two yarding engines. 
Fig. 53. — Coupling grabs. 
Fig. 54. — Log- 
ging dog. 
EQUIPMENT. 
Road engines. — Simple-geared, wide-drum engines are used for 
roading, the size and drum capacities depending on the size of timber, 
character of road, and length of haul. They are mounted on sleds 
the same as ground yarding engines and moved over the ground from 
one setting to the other by their own power. 
