A method and a control circuit for an apparatus, comprisingat least a first motor (18-21, 32-33) which is configured todrive a feeding device for feeding a tree trunk through theapparatus, and a first valve assembly (11) configured to controlthe rotation of the first motor by means of pressurizedpressure medium. The control circuit also comprises asecond valve assembly (45) configured to supply or conveypressure medium to the first motor (18-21, 32-33), wherebyit is possible to maintain a predetermined pressure level ofthe pressure medium in the first motor, or pressure mediumis available for the first motor. In an example, the apparatusis a harvester head comprising said control circuit.
