Patent ID: 7174966

Claim:
A process of setting the length of an upper steering arm of an attaching device of a tractor, wherein the attaching device comprises the upper steering arm with a power drive provided for length setting purposes, a length sensor for determining the actual length of the upper steering arm, two lower steering arms with a lifting mechanism for lifting and lowering the lower steering arms, a lift sensor for determining the actual position of lift of the lifting mechanism, as well as a control unit, said process comprising: providing nominal lengths of the upper steering arm in a memory of said control unit, said nominal lengths are stored in the control unit as a function of positions of lift and directions of movement of the lifting mechanism to be determined; determining the actual length of the upper steering arm; determining the actual position of lift of the lifting mechanism; determining the lifting direction of movement or the lowering direction of movement of the lifting mechanism; comparing the actual length with the stored nominal length for the lifting or lowering direction of movement to be determined and for the actual position of lift to be determined; and controlling the power drive for setting the length of the upper steering arm to the nominal length if the actual length deviates from the nominal length.