Abstract: Disclosed herein is a vehicle (1)—preferably a tractor—with a trailer (2) operatively connected thereto with a cardan (3), said cardan (3) comprising a power take-off, said power take-off being switched off when said cardan (3) builds with said vehicle (1) and/or with said trailer (2) an angle (?) smaller than a first threshold value (a) and/or larger than a second threshold value (?) and being switched on when said angle (?) exceeds again said first threshold value (?) thanks to suitable actuators, including detection means of the angle formed between the cardan (3) and said vehicle and/or trailer. According to the present invention, said angle (?) is detected by a detector consisting of a magnetic device (4) placed on the trailer (2) or the vehicle (1) and an electronic compass (5) placed on the vehicle (1) or on the trailer (2).