Abstract: A sealing device is disclosed for maintaining a small positive clearance between the sealing sectors and the turbine blade tips of a turbojet engine. The sealing segments are connected to an internal ring structure and an external ring structure located within the casing of the jet engine. The two ring structures serve to expand and contract the diameter of the ring formed by the sealing segments in conjunction with the expansion and contraction of the turbine blades for stabilized and transient engine operating modes. The device utilizes ventilating air taken from a stage of the jet engine compressor to cause the radial expansion or contraction of the internal and external rings in direct conjunction with the conditions under which the engine is operating.