A debarking harvester head of single-grip type, comprising a feed unit, a frame with a trunk feed track whose direction of transport coincides with a longitudinal axis of a tree trunk that has been taken into the harvester head, and where the said feed unit comprises, two of feed units (11, 12) that are each supported on a grip arm (3a, 3b) for pivoting towards and away from the trunk feed track around an axis that are in the harvester head for each grip arm, in order to be able to grip a tree trunk between them, whereby each feed unit (11, 12) supports a combination of a pair of a first feeder roller (11a, 11b) and a second feeder roller (12a, 12b) wherein the first feeder rollers (11a, 11b) are each configured to be rotated around a central axis (11a', 11b') and comprise radially protruding grip means (13, 14) for penetrating into the tree trunk in order to cause it to rotate around its longitudinal axis such that bark is freed from the circumference of the trunk at the same time as it is fed forwards in the direction of transport, and the second feeder rollers (12a, 12b) are each configured to be rotated around a central axis (12a', 12b'), whereby the two central axes (11a', 11b') of first feeder rollers (11a, 11b), respectively, are arranged at a such distance from each other when viewed in the direction of transport that they form during the gripping operation a force-producing pair that acts on the tree trunk that can apply to the tree trunk with a lever (a1, a2), respectively, a turning torque around a central axis of pivot that passes transversely through the tree trunk, and the two central axes (12a', 12b') of the second feeder rollers (12a, 12b) respectively, are arranged at such a distance from the central axis of pivot when viewed in the direction of transport that they together form a counteracting force that can act with a relevant lever (b1, b2) to support the tree trunk, a feed unit, a frame with a trunk feed track whose direction of transport coincides with a longitudinal axis of a tree trunk that has been taken into the harvester head, and where the said feed unit comprises, two of feed units (11, 12) that are each supported on a grip arm (3a, 3b) for pivoting towards and away from the trunk feed track around an axis that are in the harvester head for each grip arm, in order to be able to grip a tree trunk between them, whereby each feed unit (11, 12) supports a combination of a pair of a first feeder roller (11a, 11b) and a second feeder roller (12a, 12b) wherein the first feeder rollers (11a, 11b) are each configured to be rotated around a central axis (11a', 11b') and comprise radially protruding grip means (13, 14) for penetrating into the tree trunk in order to cause it to rotate around its longitudinal axis such that bark is freed from the circumference of the trunk at the same time as it is fed forwards in the direction of transport, and the second feeder rollers (12a, 12b) are each configured to be rotated around a central axis (12a', 12b'), whereby the two central axes (11a', 11b') of first feeder rollers (11a, 11b), respectively, are arranged at a such distance from each other when viewed in the direction of transport that they form during the gripping operation a force-producing pair that acts on the tree trunk that can apply to the tree trunk with a lever (a1, a2), respectively, a turning torque around a central axis of pivot that passes transversely through the tree trunk, and the two central axes (12a', 12b') of the second feeder rollers (12a, 12b) respectively, are arranged at such a distance from the central axis of pivot when viewed in the direction of transport that they together form a counteracting force that can act with a relevant lever (b1, b2) to support the tree trunk,