Abstract: A scarifier or ripper attachment for a tractor or like vehicle, comprising a support structure carrying a pivoted arm on the free end of which is a pivoted tool-carrying frame. The elevation of the arm is controlled by an hydraulic elevation actuator and the inclination of the tool with respect to the arm is controlled by an hydraulic attitude control actuator. The hydraulic circuit of the two actuators includes an auxiliary distributor having three positions in one of which the two actuators are connected in series so that one retracts when the other extends, and in the other two of which one or the other actuator is isolated so that the other can be controlled independently. The relative diameters of the two actuators are such that in the first position of the auxiliary distributor the tool is held in a fixed orientation in relation to the ground as the arm is turned through its full angle.