Abstract: The invention concerns a forest harvester suspended pivotally at the end of a crane jib (1) and rotatable around its shaft of suspension for felling of a tree trunk and for trimming and possible cutting-off of the tree trunk in the horizontal position. The harvester comprises a suspension arm (3) shaped substantially as an inverted L and a processor unit (4) mounted pivotally at the lower end of the arm, the side of the processor unit (4) placed facing away from the suspension arm (3) being provided with a cross-cutting member (6), with two groups of trimming members (7,8) placed at a distance from one another, and with at least two drive rolls (9, 10) jointly operative with each other, with variable mutual spacing, and mounted between said groups of trimming members.