This actuation of a differential lock consists essentially of the locking differential (10) and the coupling (11) connected thereto, which via an electromagnetic actuating means (12) connects that part of the locking differential (10) driven by the universal shaft when and as long as a predeterminable value of the steering angle is attained or exceeded. The sole signal generator used for this purpose may be, as required, realized as a contact built immediately into the switching circuit of the electromagnetic actuating means (2), or an inductive switch or potentiometer, respectively, in the area of the angle-dependent steering elements, and held fast in the axle housing (2), protected from damage. The switching means (7) is capable of being actuated either via further switches (17) and (30) manually by the driver, or may be combined with the engagement lever for the supplementary drive on steering axle (1) so that the locking differential (10) can only be actuated under appropriate driving conditions. The frequency of actuation of the locking differential (10) is thus limited to the essential cases of necessity, and a simpler and more robust engagement technique is achieved.