Abstract: The present invention relates to a multipurpose device designed to prevent thefts of trailers, heavy tows and so called dollies, i.e., having coupling elements with a pull rod and a turn table, designed to haul a trailer by means of a truck, all of which being provided with coupling devices, designed to connect the trailers to a traction vehicle. The locking device comprises a box-shaped lock house (1) in which the coupling device on the tow, the trailer and the dolly is designed to be positioned and locked by means of a locking shaft (4), which is inserted through the lock house (1) and can be located in the lock house (1) in various positions, depending on the character of the coupling device to be locked, and consequently said coupling device is enclosed in the lock house (1), and the tow, the trailer or the dolly is prevented from being connected to any unauthorized traction trailer.