Abstract: A dynamic packing for sealing a shaft which passes through a wall separating an oil-containing space from an oil-free space or from the outside atmosphere, composed of two shaft sealing rings which engage the shaft and define an oil-filled gap therebetween, and a duct composed of one portion in communication with the oil-containing space and another portion in communication with the gap to place the gap between the sealing rings in communication with the oil-containing space and which is provided with a closure element in the form of a diaphragm having one of its faces in communication with both duct portions, the duct and element being provided to relieve the pressure in the gap.