Mechanism for transforming furniture from a sitting position to a lying down position

A mechanism for transforming furniture from a sitting position to a lying down position having two jacks, right and left, with identical design, which are a mirror reflection of each other connected with each other by a synchronisation mechanism, and each of these jacks has a fastening plate which attaches the jack to the furniture body, angle bars, upper and lower for connecting with the mattresses, a spring and a front pull rod and rear pull rod with centre arms, whereas the pull rods of each jack with one of their ends are connected in an articulated manner with the upper angle bar, and the second end are connected in an articulated manner with the fastening plate, and the centre arms are connected in an articulated manner with the bottom angle bar, characterised in that each jack has a backrest driving sub-assembly created from a backrest rotation pull rod and support to be connected with the backrest of the furniture, whereas the backrest rotation pull rod is connected in an articulated manner on one end with the bottom end of the rear pull rod, and on the second end is connected in an articulated manner with the support connected in an articulated manner to the fastening plate.