Abstract: A trailer having a variable configuration for carrying heavy loads, including: a main frame, a main suspension system supporting the rear of the main frame, coupling mechanism for coupling the main frame to a power unit with or without an auxiliary trailer and for supporting the front of the frame. Mechanisms for coupling on a variety of auxiliary frames are provided, for the purpose of distributing the weight of the payload and the weight of the trailer itself according to legal requirements and requirements of safety. These mechanisms generally include a front suspension arm joining the main suspension to the auxiliary frame, a main pivot between the main frame and the auxiliary frame, and an additional connecting link between main and auxiliary frames.