Abstract Use of feller-buncher and directional shears has increased the productivity and efficiency of many logging operations in the South. When felling sawlog and chip'n' saw-sized timber, hydraulic shears can damage the butt portion of the tree. Butt logs of trees felled with shears are subjectto damage in the form of ring-shake, stump-pull, shatter, and splitting (Porter et al. 1984). Logging equipment manufacturers have attempted to minimize shear-related damage through different felling head designs. Various designs have included ribbed blades, angled shear patterns, curved blades,modified blade angles, and modified shear speeds. Whereas a number of studies addressed the effect of a specific design on shear-related damage (Guimier 1981, Forrester 1980, Redman 1979, McLaucalan and Kusec 1974, Letkeman 1973, Johnson and St. Laurent 1970, McIntosh and Kerbes 1968), fewhave compared designs to determine the relative advantage of one over another in reducing shear-related damage. This paper presents the results of a recent study comparing six feller-buncher and directional shear head designs to determine their relative abilities in reducing shear-relateddamage. The study also details a quick and inexpensive method of quantifying shear-related damage in butt logs. South. J. Appl. For. 11(1):3-6.
 scale(.12937)'%3e %3csvg width='12' viewBox='-120 -190.223125 240 309.188274' height='15.459'%3e %3cpath d='m110.26-19.478l9.74-143.75a280.22 280.22 0 0 0 -240 0l9.74 143.75a155.61 155.61 0 0 0 110.26 138.45 155.61 155.61 0 0 0 110.26 -138.45' fill='%23005da4'/%3e %3cpath d='m-90 0a138.29 138.29 0 0 0 90 100.77 138.29 138.29 0 0 0 90 -100.77l-45-60-18 24-27-54-27 54-18-24-45 60' fill='%23fff'/%3e %3cg id='wave' fill='%23005da4' transform='scale(5) translate(0 5.1962)'%3e %3cpath d='m-17.196-2.1962a6 6 0 0 0 8.1962 2.1962 6 6 0 0 1 6 0 6 6 0 0 0 6 0 6 6 0 0 1 6 0 6 6 0 0 0 8.1962 -2.1962v1.732a6 6 0 0 1 -8.1962 2.1962 6 6 0 0 0 -6 0 6 6 0 0 1 -6 0 6 6 0 0 0 -6 0 6 6 0 0 1 -8.1962 -2.1962z'/%3e %3c/g%3e %3cuse xlink:href='%23wave' transform='translate(0 17.321)'/%3e %3cg id='s' transform='translate(0,-120) scale(2.25)'%3e %3cpath stroke-width='.2' d='m0-5l1 3.2679 3.3301-0.7679-2.3301 2.5 2.3301 2.5-3.3301-0.7679-1 3.2679-1-3.2679-3.3301 0.7679 2.3301-2.5-2.3301-2.5 3.3301 0.7679z' fill='%23fd0'/%3e %3c/g%3e %3cuse xlink:href='%23s' transform='translate(-33.75,-45)'/%3e %3cuse xlink:href='%23s' transform='translate(33.75,-45)'/%3e %3cpath d='m-111.58-167.05l9.96 146.99a146.95 146.95 0 0 0 101.62 129.95 146.95 146.95 0 0 0 101.62 -129.95l9.96-146.99a280.22 280.22 0 0 0 8.42 3.82l-9.74 143.75a155.61 155.61 0 0 1 -110.26 138.45 155.61 155.61 0 0 1 -110.26 -138.45l-9.74-143.75a280.22 280.22 0 0 0 8.42 -3.82' fill='%23ed1c24'/%3e %3c/svg%3e %3c/g%3e %3c/svg%3e)
