Simplified anti-vibration suspension device with top dampers for a helicopter

An anti-vibration suspension device, for a helicopter main rotor including a rotor mast rotated by a main transmission box around an axis of the mast, which is the axis of rotation of the rotor, the suspension device including at least three rigid diagonal bars supporting the transmission box on the helicopter structure, the diagonal bars being distributed around the transmission box and inclined on the rotor axis so as to converge in the direction of their upper ends towards each other and substantially towards a point of the rotor axis, the diagonal bars being connected in an articulated way, on the one hand, to the helicopter structure by their lower ends, and, on the other hand, to the transmission box by their upper ends and by means of rigid levers, equal in number to the diagonal bars, each lever pointing substantially from the top of the transmission box and from the upper end of the corresponding diagonal bar towards the base of said box and/or the lower end of said diagonal bar, each lever supporting at least one damping weight at its lower end and being connected in an articulated way to the transmission box by its upper end part, on which the upper end of the corresponding diagonal bar is articulated, the articulations connecting each lever to said box and to the corresponding diagonal bar being articulations at least pivoting around axes substantially perpendicular to a corresponding radial plane passing through the rotor axis and through the longitudinal axis of the corresponding diagonal bar, wherein, for each diagonal bar a tension bar, flexible in tension, is also inclined on the rotor axis in the corresponding radial plane so that the tension bars converge towards each other in the direction of their upper ends, each tension bar being articulated by its upper end on the transmission box and by its lower end on the helicopter structure, and the corresponding lever is connected in an articulated way to said box while being articulated, at least pivoting, around an axis substantially perpendicular to said corresponding radial plane, on the upper end part of the tension bar.