Method and an apparatus for cross-cutting trees

An apparatus for cutting tree trunks to length, comprising in combination lopping means for cutting off branches from the trunks, cutting means for cutting off the trunk, advancing means for moving the trunk lengthwise past the lopping means and the cutting means, means for measuring the lengthwise movement of the tree trunk, a control unit receiving from said measuring means a length signal representing the length advance of the trunk and generating in response to length advance control signals for the advancing means and for the cutting means, at least one transducer that measures the cutting force applied by the lopping means to cut off the branch or the branches momentarily engaging the lopping means, said transducer generating a lopping force signal representative of that cutting force, said control unit having an input for the lopping force signal and combining said lopping force signal with the length signal into at least one knot signal representing the presence of knots on the tree trunk, said control unit transmitting said control signals to the advancing means and to the cutting means as a function of the knot signal thereby to cut off the trunk at locations that are well chosen relative to the locations of the Knots.