Abstract:
This paper describes the results of a time study conducted on the
Sierra National Forest to determine production capacity of the Madill 044
Skyline Yarding Crane operating in a partial cut situation for old-growth
mixed conifer stands. The yarder was rigged in the running skyline configuration
and used a Danebo mechanical slackpulling (MSP) carriage. Yarding
distances ranged from 40 to 900 feet and lateral yarding distances ranged
from 0 to 185 feet. An average of 35 thousand board feet of timber per
acre was removed from the study area.
- Regression equations were developed for the individual elements of
the yarding cycle and for total cycle time. Results indicate that skyline
yarding distance, lateral yarding distance and number of logs per
turn are the most significant variables related to predicting total turn
time, with cubic volume per turn and the number of workers on the rigger
crew playing a less important role.
A couiparison of the regression developed for the Madill 044 with
another regression model for a Washington Iron Works 108 skyline yarding
crane suggests that there is an approximate 33% difference in total turn
times predicted for the same logging conditions.
