Development of a puller-buncher for harvesting southern pines without taproot attached

Abstract

A harvester-buncher that mounts on the front of a wheeled skidder has been developed to pull entire pine trees from the ground like carrots. Two elements are central to its design. The first is a scissor-type grib equipped with a pair of sout horizontal knife blades that close at the groundline and bite several inches into the stem from oposite sides of the tre. The second element in the design is a clamshell-hinged tubular shear 22 inches in diameter and sharpened on the lower edge. With the scissors grip as an anchor, the shear is forced vertically into the ground to a depth of about 11 inches, severing lateral roots all around the tree. At this depth, broad steps on opposite sides of the tubular shear strike the ground onad prevent further penetration; application of additional force on the shear causes the steps to bear against the ground and the grip to rise about 9 inches, thereby jacking the tree free of the ground with taproot attached. Finally, the complete tree is lifted into the air and bunched for skidding. With this equipment southern pines up to 13 inches in diameter were harvested and bunched at sustained rates of 1 to 2 trees per minute. For 16-year-old loblolly pines on dry loamy-clay soil, force to sever lateral roots (including force to penetrate soil) did not exceed 75,000 pounds; lifting force did not exceed 65,000 pounds. The stump-taproot portion of loblolly pines harvested near Cedartown, Georgia, averaged 18 percent of the gree weight of merchantable stems from 2-inch stump height to about a 3-inch top diameter outside bark. In slash pine and longleaf pine plantaitons row-thinned near Panama City, Florida, the stump-taproot averaged 22 percent of merchantable stem weight to a 2-inch top outside bark. On loamy-clay soils considerable dirt adhered to the taproots, but slash and longleaf pines pulled from sandy soils did not dull knives excessively when chipped entire. Several thousand slash and longleaf pines with taproots attached were processed through a drum debarker, chipped, and converted into kraft paper without unusual problems immediately detectable.

Citation

Koch, Peter; Coughran, S.J. 1975. Development of a puller-buncher for harvesting southern pines without taproot attached. Forest Products Journal, Vol. 25(4): 23-30