Abstract: A coupling system between a set of components to be mutually assembled comprising a box-like body that contains an electric motor, a corresponding head and a junction box that contains the elements for electrical connection, comprising a first protrusion that protrudes from an axial wall arranged at the bottom of the box-like body and provided with a first opening in which the axial electrical connectors for the motor are arranged. The junction box is engaged slidingly, upon assembly, in the wall and encounters a first retention element constituted by the first protrusion and a second retention element constituted by the head. The junction box is provided with connection elements that are connected to an internal terminal strip and are aligned so as to match and couple the electrical connectors.