Produktionsskillnader och virkesskador med olika typer av matarvalsar

Abstract: Earlier investigations showed that damages on timber from feeding rolls could be within the lower classes of damage according to VMRs classes. Knowledge about differences in productivity between kind types and aggressive types of feeding rolls is necessary because it should influence the question about damages on timber caused by different feeding rolls. In this study the production and timber damage in a harvesting head were evaluated at three levels of pressure (8, 10 and 14 MPa) on the feeding rolls, and with three different types of rolls. One type, the rubber cushioned steel plate roller had 10 mm studs and rubber damping, one "middle" type made of solid steel with 14 mm studs, and one aggressive type, also made of solid steel with 18 mm studs. No significant general difference in productivity between the three types could be found, but the pressure on the feeding rolls influenced clearly the productivity. The depth of the damages lied within the lower classes according to VMR. The two steel wheels gave at all pressure levels a deeper damage than type one. There was no difference in the depth of the damages between the tested pressure levels for the two steel wheel types whereas for the kind type there was a difference. None of the feeding roll types showed a bark abrasion that would be classified as "extensive" according to VMR. The lower pressure (8 MPa) caused a little more bark abrasion for the steel rolls. The kind type caused even at 10 and 14 MPa a little more bark abrasion than the both steel rolls.