System for locking doors on goods boxes, involving a mechanism that consists of an operating lever (4), to which attachment is made of a set of knuckle-jointed connecting rods (7 and 8) pivoting like a compass, forming a four-sided articulated arrangement that is operated by use of the lever (4) in order to lock and release the respective head arrangements (10 and 12) with regard their corresponding lock attachment housings (11 and 13).