This study investigated the potential use of wide skidder
tires for forest harvesting operations on steep slopes. During the summer of 1984, field tests were conducted to
compare the performance characteristics of 24.5-32 and 66-43
rubber tires on a JD-640 grapple skidder loaded with tree
length material. The skidder was operated on 20%, 25% and
30% slopes on Piedmont soils near Rome, Georgia.
Video recorders were used to document the field measurements
and observations of machine travel time and wheel slip
over defined courses. Soil compaction was evaluated by comparing
soil cone penetrometer readings taken in the wheel
tracks of the test lanes to those taken in undisturbed adjacent
areas. Skidder lateral stability was analyzed using the
mathematical model developed in this study.
Based on the results of statistical analyses of the data
and field observations obtained under the test conditions,
the skidder equipped with wide tires generally attained
higher average speeds, tended to cause less wheel slip, resulted in smaller increases in soil cone penetrometer
readings, and had significantly greater stability on
sideslopes than the skidder equipped with the narrow tires.
The stability model developed in this study predicted the
critical sideways tipping angle for a JD—64O grapple skidder
to be approximately 32° when fitted with the 24.5-32 tires,
and 44° when fitted with the 66-43 tires.
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