Abstract: The present invention relates to a device for opening out and folding back one or more thermal screens by a plurality of extensible chambers moving over and around guiding hoops, which chambers comprise a piston forming the movable ends of the chambers, which device comprises, close to and under the piston of each retracted air chamber, a deformable membrane borne by a structure and placed in contact with the periphery of the chamber and whose function is to slow down the extension of the chamber when the latter is pressurized, in order to ensure a good air distribution in the inflated part of said chamber and so prevent that part from winding itself around the guiding hoop when the screen is opened out.