Abstract: For automatically controlling a differential lock in drive axles of a motor vehicle, an arrangement has a lock coupling, an actuator for actuating the lock coupling, a plurality of rotary speed sensors associated with wheels of the vehicle for forming the rotary speed signal, a control unit for receiving the rotary speed signals and forming a control signal for controlling the actuator means, the control unit including computing means for computing a nominal rotary speed value associated with each of the wheels so that a computed nominal rotary speed value is determined continuously in dependence from a corresponding traveling condition, a first comparing unit for forming a difference rotary speed value from a comparison of a measured rotary speed value with the computed nominal rotary speed value, and a second comparing unit for forming the control signal so that when the difference rotary speed value exceeds a predetermined threshold value the lock coupling is engaged and when the difference rotary speed va