The method involves providing a safety device with a mechanical operated ballast valve within hydraulic working circuit and switching the mechanical operated ballast valve from a flow position into a locking position. The ballast valve is switched according to the principle of inevitable mechanical reciprocal effect due to transferring of a cultivation unit from a ground level working position (32) or intermediate position into a ground-remote transport position (29). An independent claim is also included for a device for producing a safety device of a hydraulic working circuit for operating folding or flap mechanisms of agricultural attachments for rear or front extension at tractor for transportation from transporting position in a working position.
