Knot Trimmer

a machine used to clear felled trees of knots. Knot trimmers may be self-propelled for use at timber-felling sites or in loading areas at felling sites, or they may be stationary for use in lower woodyards. Knot trimmers that process felled trees singly consist of mechanisms for feeding, cutting, and pulling the trees through the machine. In some of these machines the cutting mechanism moves along the tree trunk, which is held fixed. Knot trimmers that process in batches clear the trees of knots by mutual friction of two or more tree trunks and by friction with the walls of the machine’s V-shaped hopper. The productivity of stationary knot trimmers reaches 800 cu m per shift for hopper volumes of 25–40 cu m. In knot trimmers that process single trees, the cutting zone is capable of handling trees 8–50 cm in diameter. Machines that combine knot-trimming and bucking operations and knot-trimming and felling operations are under development, as well as combination logging machines for felling trees, trimming knots, bucking into graded sizes, and other operations.