Disclosed is a method of operating a timber-working device (4) that includes pivoting delimb arms and pivoting drive arms (11a, 11b). Indications of both an angular position of at least one of the delimb arms is and of an angular position of at least one of the drive arms (11a, 11b) are received. The angular position of the delimb arm is then correlated with the angular position of the drive (11a, 11b) arm to determine the number of stems currently grasped by the timber-working device (4).
