Abstract: A harvester head, comprising a measuring wheel apparatus with a measuring wheel configured to roll along a tree trunk when the trunk is fed through the harvester head, and a power device configured to swivel the measuring wheel apparatus and to keep the measuring wheel pressed against the tree trunk. The measuring wheel is configured to remain in an elevated position in relation to the frame structure of the harvester head, wherein the measuring wheel also has a supporting position to support the trunk and to provide a supporting force that does not let the trunk fall against the frame structure. A measuring wheel apparatus which is applicable in a harvester head, comprising a measuring wheel with a supporting position to support a tree trunk, and which comprises a stopping member configured to stop the swinging motion of the measuring wheel apparatus when the measuring wheel assumes said supporting position.