The hydropneumatic membrane chair consists of a chamber d with a variable volume with the elastic membrane 17 attached between lid 18 and cylinder 19 provided with a valve 8. In the cylinder 19 with damping liquid, the piston 9 slides, together with the rod 20, hinged to the support 21. In the valve 9 is inserted, at the commissioning of the seat, medium pressure air (3.5 4.5 bar) according to the driver's weight.